* [PATCH RFC v4 04/18] fs/resctrl: Add resctrl_is_membw() helper
From: Drew Fustini @ 2026-05-11 5:11 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Alexandre Ghiti,
Radim Krčmář, Samuel Holland, Adrien Ricciardi,
Nicolas Pitre, Kornel Dulęba, Atish Patra, Atish Kumar Patra,
Vasudevan Srinivasan, Ved Shanbhogue, Conor Dooley, yunhui cui,
Chen Pei, Liu Zhiwei, Weiwei Li, guo.wenjia23, Gong Shuai,
Gong Shuai, liu.qingtao2, Reinette Chatre, Tony Luck, Babu Moger,
Peter Newman, Fenghua Yu, James Morse, Ben Horgan, Dave Martin,
Rob Herring, Conor Dooley, Krzysztof Kozlowski, Rafael J. Wysocki,
Len Brown, Robert Moore, Sunil V L, Drew Fustini, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, Dave Hansen, H. Peter Anvin,
Sebastian Andrzej Siewior, Clark Williams, Steven Rostedt,
Jonathan Corbet
Cc: linux-kernel, linux-riscv, x86, linux-acpi, acpica-devel,
devicetree, Paul Walmsley, Conor Dooley, linux-rt-devel,
linux-doc, Palmer Dabbelt
In-Reply-To: <20260510-ssqosid-cbqri-rqsc-v7-0-v4-0-eb53831ef683@kernel.org>
Four sites in fs/resctrl distinguish bandwidth resources (MBA, SMBA)
from cache resources by explicit rid match:
fs/resctrl/ctrlmondata.c parse_line()
fs/resctrl/rdtgroup.c rdtgroup_mode_test_exclusive()
fs/resctrl/rdtgroup.c rdtgroup_size_show()
fs/resctrl/rdtgroup.c rdtgroup_init_alloc()
Replace the open-coded MBA/SMBA tests with a single resctrl_is_membw()
helper keyed on schema_fmt (RESCTRL_SCHEMA_RANGE). No functional change:
every existing RESCTRL_SCHEMA_RANGE resource is MBA or SMBA today.
This isolates fs/resctrl from the addition of further bandwidth resource
types so the four call sites do not have to be updated for each new rid.
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Drew Fustini <fustini@kernel.org>
---
fs/resctrl/ctrlmondata.c | 3 +--
fs/resctrl/internal.h | 2 ++
fs/resctrl/rdtgroup.c | 14 +++++++++-----
3 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 9a7dfc48cb2e..d9f052700941 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -245,8 +245,7 @@ static int parse_line(char *line, struct resctrl_schema *s,
if (WARN_ON_ONCE(!parse_ctrlval))
return -EINVAL;
- if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP &&
- (r->rid == RDT_RESOURCE_MBA || r->rid == RDT_RESOURCE_SMBA)) {
+ if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP && resctrl_is_membw(r)) {
rdt_last_cmd_puts("Cannot pseudo-lock MBA resource\n");
return -EINVAL;
}
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 1a9b29119f88..76187987b2ee 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -397,6 +397,8 @@ void mbm_handle_overflow(struct work_struct *work);
bool is_mba_sc(struct rdt_resource *r);
+bool resctrl_is_membw(struct rdt_resource *r);
+
void cqm_setup_limbo_handler(struct rdt_l3_mon_domain *dom, unsigned long delay_ms,
int exclude_cpu);
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5dfdaa6f9d8f..0f331bf5ce82 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1412,7 +1412,7 @@ static bool rdtgroup_mode_test_exclusive(struct rdtgroup *rdtgrp)
list_for_each_entry(s, &resctrl_schema_all, list) {
r = s->res;
- if (r->rid == RDT_RESOURCE_MBA || r->rid == RDT_RESOURCE_SMBA)
+ if (resctrl_is_membw(r))
continue;
has_cache = true;
list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
@@ -1555,6 +1555,12 @@ bool is_mba_sc(struct rdt_resource *r)
return r->membw.mba_sc;
}
+/* RANGE schema is bandwidth (MBA/SMBA). BITMAP is cache. */
+bool resctrl_is_membw(struct rdt_resource *r)
+{
+ return r->schema_fmt == RESCTRL_SCHEMA_RANGE;
+}
+
/*
* rdtgroup_size_show - Display size in bytes of allocated regions
*
@@ -1616,8 +1622,7 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
ctrl = resctrl_arch_get_config(r, d,
closid,
type);
- if (r->rid == RDT_RESOURCE_MBA ||
- r->rid == RDT_RESOURCE_SMBA)
+ if (resctrl_is_membw(r))
size = ctrl;
else
size = rdtgroup_cbm_to_size(r, d, ctrl);
@@ -3648,8 +3653,7 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
list_for_each_entry(s, &resctrl_schema_all, list) {
r = s->res;
- if (r->rid == RDT_RESOURCE_MBA ||
- r->rid == RDT_RESOURCE_SMBA) {
+ if (resctrl_is_membw(r)) {
rdtgroup_init_mba(r, rdtgrp->closid);
if (is_mba_sc(r))
continue;
--
2.43.0
^ permalink raw reply related
* [PATCH RFC v4 03/18] riscv: add support for srmcfg CSR from Ssqosid extension
From: Drew Fustini @ 2026-05-11 5:10 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Alexandre Ghiti,
Radim Krčmář, Samuel Holland, Adrien Ricciardi,
Nicolas Pitre, Kornel Dulęba, Atish Patra, Atish Kumar Patra,
Vasudevan Srinivasan, Ved Shanbhogue, Conor Dooley, yunhui cui,
Chen Pei, Liu Zhiwei, Weiwei Li, guo.wenjia23, Gong Shuai,
Gong Shuai, liu.qingtao2, Reinette Chatre, Tony Luck, Babu Moger,
Peter Newman, Fenghua Yu, James Morse, Ben Horgan, Dave Martin,
Rob Herring, Conor Dooley, Krzysztof Kozlowski, Rafael J. Wysocki,
Len Brown, Robert Moore, Sunil V L, Drew Fustini, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, Dave Hansen, H. Peter Anvin,
Sebastian Andrzej Siewior, Clark Williams, Steven Rostedt,
Jonathan Corbet
Cc: linux-kernel, linux-riscv, x86, linux-acpi, acpica-devel,
devicetree, Paul Walmsley, Conor Dooley, linux-rt-devel,
linux-doc, Palmer Dabbelt
In-Reply-To: <20260510-ssqosid-cbqri-rqsc-v7-0-v4-0-eb53831ef683@kernel.org>
Add support for the srmcfg CSR defined in the Ssqosid ISA extension.
The CSR contains two fields:
- Resource Control ID (RCID) for resource allocation
- Monitoring Counter ID (MCID) for tracking resource usage
Requests from a hart to shared resources are tagged with these IDs,
allowing resource usage to be associated with the running task.
Add a srmcfg field to thread_struct with the same format as the CSR so
the scheduler can set the RCID and MCID for each task on context
switch. A per-cpu cpu_srmcfg variable mirrors the CSR state to avoid
redundant writes. L1D-hot memory access is faster than a CSR read and
avoids traps under virtualization.
A per-cpu cpu_srmcfg_default holds the default srmcfg for each CPU as
set by resctrl CPU group assignment. On context switch, if the next
task belongs to the default resource group (srmcfg == 0), the CPU's
default value is used instead. This implements resctrl allocation
rule 2: default-group tasks on a CPU assigned to a specific group
receive that group's allocations.
Link: https://github.com/riscv/riscv-ssqosid/releases/tag/v1.0
Assisted-by: Claude:claude-opus-4-7
Co-developed-by: Kornel Dulęba <mindal@semihalf.com>
Signed-off-by: Kornel Dulęba <mindal@semihalf.com>
Signed-off-by: Drew Fustini <fustini@kernel.org>
---
MAINTAINERS | 8 +++++
arch/riscv/Kconfig | 18 +++++++++++
arch/riscv/include/asm/csr.h | 5 +++
arch/riscv/include/asm/processor.h | 3 ++
arch/riscv/include/asm/qos.h | 64 ++++++++++++++++++++++++++++++++++++++
arch/riscv/include/asm/switch_to.h | 3 ++
arch/riscv/kernel/Makefile | 2 ++
arch/riscv/kernel/qos.c | 49 +++++++++++++++++++++++++++++
8 files changed, 152 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 4d1e198959e4..5039f48f387a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -23006,6 +23006,14 @@ F: drivers/perf/riscv_pmu.c
F: drivers/perf/riscv_pmu_legacy.c
F: drivers/perf/riscv_pmu_sbi.c
+RISC-V QOS RESCTRL SUPPORT
+M: Drew Fustini <fustini@kernel.org>
+R: yunhui cui <cuiyunhui@bytedance.com>
+L: linux-riscv@lists.infradead.org
+S: Supported
+F: arch/riscv/include/asm/qos.h
+F: arch/riscv/kernel/qos.c
+
RISC-V RPMI AND MPXY DRIVERS
M: Rahul Pathak <rahul@summations.net>
M: Anup Patel <anup@brainfault.org>
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d235396c4514..a7e87c49be21 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -591,6 +591,24 @@ config RISCV_ISA_SVNAPOT
If you don't know what to do here, say Y.
+config RISCV_ISA_SSQOSID
+ bool "Ssqosid extension support for supervisor mode Quality of Service ID"
+ depends on 64BIT
+ default n
+ help
+ Adds support for the Ssqosid ISA extension (Supervisor-mode
+ Quality of Service ID).
+
+ Ssqosid defines the srmcfg CSR which allows the system to tag the
+ running process with an RCID (Resource Control ID) and MCID
+ (Monitoring Counter ID). The RCID is used to determine resource
+ allocation. The MCID is used to track resource usage in event
+ counters.
+
+ For example, a cache controller may use the RCID to apply a
+ cache partitioning scheme and use the MCID to track how much
+ cache a process, or a group of processes, is using.
+
config RISCV_ISA_SVPBMT
bool "Svpbmt extension support for supervisor mode page-based memory types"
depends on 64BIT && MMU
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 31b8988f4488..7bce928e5daa 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -84,6 +84,10 @@
#define SATP_ASID_MASK _AC(0xFFFF, UL)
#endif
+/* SRMCFG fields */
+#define SRMCFG_RCID_MASK GENMASK(11, 0)
+#define SRMCFG_MCID_MASK GENMASK(27, 16)
+
/* Exception cause high bit - is an interrupt if set */
#define CAUSE_IRQ_FLAG (_AC(1, UL) << (__riscv_xlen - 1))
@@ -328,6 +332,7 @@
#define CSR_STVAL 0x143
#define CSR_SIP 0x144
#define CSR_SATP 0x180
+#define CSR_SRMCFG 0x181
#define CSR_STIMECMP 0x14D
#define CSR_STIMECMPH 0x15D
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 812517b2cec1..49a386d74cd3 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -123,6 +123,9 @@ struct thread_struct {
/* A forced icache flush is not needed if migrating to the previous cpu. */
unsigned int prev_cpu;
#endif
+#ifdef CONFIG_RISCV_ISA_SSQOSID
+ u32 srmcfg;
+#endif
};
/* Whitelist the fstate from the task_struct for hardened usercopy */
diff --git a/arch/riscv/include/asm/qos.h b/arch/riscv/include/asm/qos.h
new file mode 100644
index 000000000000..6988fe37551e
--- /dev/null
+++ b/arch/riscv/include/asm/qos.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_QOS_H
+#define _ASM_RISCV_QOS_H
+
+#include <linux/percpu-defs.h>
+
+#ifdef CONFIG_RISCV_ISA_SSQOSID
+
+#include <linux/cpufeature.h>
+#include <linux/sched.h>
+
+#include <asm/csr.h>
+#include <asm/fence.h>
+#include <asm/hwcap.h>
+
+/* cached value of srmcfg csr for each cpu */
+DECLARE_PER_CPU(u32, cpu_srmcfg);
+
+/* default srmcfg value for each cpu, set via resctrl cpu assignment */
+DECLARE_PER_CPU(u32, cpu_srmcfg_default);
+
+static inline void __switch_to_srmcfg(struct task_struct *next)
+{
+ u32 thread_srmcfg;
+
+ thread_srmcfg = READ_ONCE(next->thread.srmcfg);
+
+ /* Default-group tasks (thread.srmcfg == 0) follow this CPU's default. */
+ if (thread_srmcfg == 0)
+ thread_srmcfg = __this_cpu_read(cpu_srmcfg_default);
+
+ if (thread_srmcfg != __this_cpu_read(cpu_srmcfg)) {
+ /*
+ * Drain stores from the outgoing task before the CSR write
+ * so they retain the previous RCID/MCID tag at the cache
+ * interconnect.
+ */
+ RISCV_FENCE(rw, o);
+
+ __this_cpu_write(cpu_srmcfg, thread_srmcfg);
+ csr_write(CSR_SRMCFG, thread_srmcfg);
+ /*
+ * Order the csrw before the new task's loads/stores so they
+ * pick up the new tag. Zicsr 6.1.1 makes CSR writes weakly
+ * ordered (device-output) vs memory ops. Ssqosid v1.0 is
+ * silent so honor the general CSR rule.
+ */
+ RISCV_FENCE(o, rw);
+ }
+}
+
+static __always_inline bool has_srmcfg(void)
+{
+ return riscv_has_extension_unlikely(RISCV_ISA_EXT_SSQOSID);
+}
+
+#else /* ! CONFIG_RISCV_ISA_SSQOSID */
+
+struct task_struct;
+static __always_inline bool has_srmcfg(void) { return false; }
+static inline void __switch_to_srmcfg(struct task_struct *next) { }
+
+#endif /* CONFIG_RISCV_ISA_SSQOSID */
+#endif /* _ASM_RISCV_QOS_H */
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
index 0e71eb82f920..1c7ea53ec012 100644
--- a/arch/riscv/include/asm/switch_to.h
+++ b/arch/riscv/include/asm/switch_to.h
@@ -14,6 +14,7 @@
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/csr.h>
+#include <asm/qos.h>
#ifdef CONFIG_FPU
extern void __fstate_save(struct task_struct *save_to);
@@ -119,6 +120,8 @@ do { \
__switch_to_fpu(__prev, __next); \
if (has_vector() || has_xtheadvector()) \
__switch_to_vector(__prev, __next); \
+ if (has_srmcfg()) \
+ __switch_to_srmcfg(__next); \
if (switch_to_should_flush_icache(__next)) \
local_flush_icache_all(); \
__switch_to_envcfg(__next); \
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index cabb99cadfb6..ebe1c3588177 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -128,3 +128,5 @@ obj-$(CONFIG_ACPI_NUMA) += acpi_numa.o
obj-$(CONFIG_GENERIC_CPU_VULNERABILITIES) += bugs.o
obj-$(CONFIG_RISCV_USER_CFI) += usercfi.o
+
+obj-$(CONFIG_RISCV_ISA_SSQOSID) += qos.o
diff --git a/arch/riscv/kernel/qos.c b/arch/riscv/kernel/qos.c
new file mode 100644
index 000000000000..75bda2ed89e1
--- /dev/null
+++ b/arch/riscv/kernel/qos.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/cpu.h>
+#include <linux/cpuhotplug.h>
+#include <linux/percpu-defs.h>
+#include <linux/types.h>
+
+#include <asm/cpufeature-macros.h>
+#include <asm/hwcap.h>
+#include <asm/qos.h>
+
+/* cached value of srmcfg csr for each cpu */
+DEFINE_PER_CPU(u32, cpu_srmcfg);
+
+/* default srmcfg value for each cpu, set via resctrl cpu assignment */
+DEFINE_PER_CPU(u32, cpu_srmcfg_default);
+
+/*
+ * Seed the per-CPU srmcfg cache to a sentinel that no real srmcfg encoding
+ * can produce (MCID << 16 | RCID, both fields well under 16 bits) so the
+ * next __switch_to_srmcfg() unconditionally writes the CSR. Ssqosid v1.0
+ * leaves CSR state across hart stop/start implementation-defined, so the
+ * cached value cannot be trusted after online.
+ */
+static int riscv_srmcfg_online(unsigned int cpu)
+{
+ per_cpu(cpu_srmcfg, cpu) = U32_MAX;
+ return 0;
+}
+
+static int __init riscv_srmcfg_init(void)
+{
+ unsigned int cpu;
+ int err;
+
+ if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SSQOSID))
+ return 0;
+
+ /* Seed already-online CPUs. The cpuhp callback covers later onlines. */
+ for_each_online_cpu(cpu)
+ per_cpu(cpu_srmcfg, cpu) = U32_MAX;
+
+ err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "riscv/srmcfg:online",
+ riscv_srmcfg_online, NULL);
+ if (err < 0)
+ pr_warn("srmcfg cpuhp registration failed (%d), cpus brought online after boot will not invalidate the CSR_SRMCFG cache\n",
+ err);
+ return err;
+}
+arch_initcall(riscv_srmcfg_init);
--
2.43.0
^ permalink raw reply related
* [PATCH RFC v4 02/18] riscv: detect the Ssqosid extension
From: Drew Fustini @ 2026-05-11 5:10 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Alexandre Ghiti,
Radim Krčmář, Samuel Holland, Adrien Ricciardi,
Nicolas Pitre, Kornel Dulęba, Atish Patra, Atish Kumar Patra,
Vasudevan Srinivasan, Ved Shanbhogue, Conor Dooley, yunhui cui,
Chen Pei, Liu Zhiwei, Weiwei Li, guo.wenjia23, Gong Shuai,
Gong Shuai, liu.qingtao2, Reinette Chatre, Tony Luck, Babu Moger,
Peter Newman, Fenghua Yu, James Morse, Ben Horgan, Dave Martin,
Rob Herring, Conor Dooley, Krzysztof Kozlowski, Rafael J. Wysocki,
Len Brown, Robert Moore, Sunil V L, Drew Fustini, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, Dave Hansen, H. Peter Anvin,
Sebastian Andrzej Siewior, Clark Williams, Steven Rostedt,
Jonathan Corbet
Cc: linux-kernel, linux-riscv, x86, linux-acpi, acpica-devel,
devicetree, Paul Walmsley, Conor Dooley, linux-rt-devel,
linux-doc, Palmer Dabbelt
In-Reply-To: <20260510-ssqosid-cbqri-rqsc-v7-0-v4-0-eb53831ef683@kernel.org>
Ssqosid is the RISC-V Quality-of-Service (QoS) Identifiers specification
which defines the Supervisor Resource Management Configuration (srmcfg)
register.
Link: https://github.com/riscv/riscv-ssqosid/releases/tag/v1.0
Co-developed-by: Kornel Dulęba <mindal@semihalf.com>
Signed-off-by: Kornel Dulęba <mindal@semihalf.com>
Signed-off-by: Drew Fustini <fustini@kernel.org>
---
arch/riscv/include/asm/hwcap.h | 1 +
arch/riscv/kernel/cpufeature.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 7ef8e5f55c8d..b83dae5cebb9 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -112,6 +112,7 @@
#define RISCV_ISA_EXT_ZCLSD 103
#define RISCV_ISA_EXT_ZICFILP 104
#define RISCV_ISA_EXT_ZICFISS 105
+#define RISCV_ISA_EXT_SSQOSID 106
#define RISCV_ISA_EXT_XLINUXENVCFG 127
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 1734f9a4c2fd..c0717a861a3c 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -582,6 +582,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
__RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
__RISCV_ISA_EXT_SUPERSET(ssnpm, RISCV_ISA_EXT_SSNPM, riscv_xlinuxenvcfg_exts),
+ __RISCV_ISA_EXT_DATA(ssqosid, RISCV_ISA_EXT_SSQOSID),
__RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
__RISCV_ISA_EXT_DATA(svade, RISCV_ISA_EXT_SVADE),
__RISCV_ISA_EXT_DATA_VALIDATE(svadu, RISCV_ISA_EXT_SVADU, riscv_ext_svadu_validate),
--
2.43.0
^ permalink raw reply related
* [PATCH RFC v4 01/18] dt-bindings: riscv: Add Ssqosid extension description
From: Drew Fustini @ 2026-05-11 5:10 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Alexandre Ghiti,
Radim Krčmář, Samuel Holland, Adrien Ricciardi,
Nicolas Pitre, Kornel Dulęba, Atish Patra, Atish Kumar Patra,
Vasudevan Srinivasan, Ved Shanbhogue, Conor Dooley, yunhui cui,
Chen Pei, Liu Zhiwei, Weiwei Li, guo.wenjia23, Gong Shuai,
Gong Shuai, liu.qingtao2, Reinette Chatre, Tony Luck, Babu Moger,
Peter Newman, Fenghua Yu, James Morse, Ben Horgan, Dave Martin,
Rob Herring, Conor Dooley, Krzysztof Kozlowski, Rafael J. Wysocki,
Len Brown, Robert Moore, Sunil V L, Drew Fustini, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, Dave Hansen, H. Peter Anvin,
Sebastian Andrzej Siewior, Clark Williams, Steven Rostedt,
Jonathan Corbet
Cc: linux-kernel, linux-riscv, x86, linux-acpi, acpica-devel,
devicetree, Paul Walmsley, Conor Dooley, linux-rt-devel,
linux-doc, Palmer Dabbelt
In-Reply-To: <20260510-ssqosid-cbqri-rqsc-v7-0-v4-0-eb53831ef683@kernel.org>
Document the ratified Supervisor-mode Quality of Service ID (Ssqosid)
extension v1.0.
Link: https://github.com/riscv/riscv-ssqosid/releases/tag/v1.0
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Drew Fustini <fustini@kernel.org>
---
Documentation/devicetree/bindings/riscv/extensions.yaml | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
index 2b0a8a93bb21..1c6f091518d4 100644
--- a/Documentation/devicetree/bindings/riscv/extensions.yaml
+++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
@@ -232,6 +232,12 @@ properties:
ratified at commit d70011dde6c2 ("Update to ratified state")
of riscv-j-extension.
+ - const: ssqosid
+ description: |
+ The standard Ssqosid extension for Quality of Service ID is
+ ratified as v1.0 in commit d9c616497fde ("Merge pull
+ request #7 from ved-rivos/Ratified") of riscv-ssqosid.
+
- const: ssstateen
description: |
The standard Ssstateen extension for supervisor-mode view of the
--
2.43.0
^ permalink raw reply related
* [PATCH RFC v4 00/18] riscv: add Ssqosid and CBQRI resctrl support
From: Drew Fustini @ 2026-05-11 5:10 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Alexandre Ghiti,
Radim Krčmář, Samuel Holland, Adrien Ricciardi,
Nicolas Pitre, Kornel Dulęba, Atish Patra, Atish Kumar Patra,
Vasudevan Srinivasan, Ved Shanbhogue, Conor Dooley, yunhui cui,
Chen Pei, Liu Zhiwei, Weiwei Li, guo.wenjia23, Gong Shuai,
Gong Shuai, liu.qingtao2, Reinette Chatre, Tony Luck, Babu Moger,
Peter Newman, Fenghua Yu, James Morse, Ben Horgan, Dave Martin,
Rob Herring, Conor Dooley, Krzysztof Kozlowski, Rafael J. Wysocki,
Len Brown, Robert Moore, Sunil V L, Drew Fustini, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, Dave Hansen, H. Peter Anvin,
Sebastian Andrzej Siewior, Clark Williams, Steven Rostedt,
Jonathan Corbet
Cc: linux-kernel, linux-riscv, x86, linux-acpi, acpica-devel,
devicetree, Paul Walmsley, Conor Dooley, linux-rt-devel,
linux-doc, Palmer Dabbelt
This RFC series adds RISC-V QoS support: the Ssqosid extension [1]
(srmcfg CSR), the CBQRI controller interface [2] integrated with
resctrl [3], and ACPI RQSC [4] for controller discovery. DT support
is possible but no platform drivers are included. The series is
also available as a branch [5].
QEMU support for Ssqosid and CBQRI lives in [6], with ACPI RQSC as
a follow-on series [7]. There is also a combined branch [8].
Series organization
-------------------
01 DT binding for Ssqosid extension
02-03 Ssqosid ISA support (detection, srmcfg CSR, switch_to)
04-06 fs/resctrl helpers and resource type additions
07-10 CBQRI device ops (cbqri_devices.c): capacity probe +
allocation, capacity monitoring, bandwidth probe +
allocation, bandwidth monitoring
11-15 CBQRI resctrl integration (cbqri_resctrl.c): cache
allocation, L3 cache occupancy monitoring, MB_MIN
bandwidth allocation, MB_WGHT bandwidth allocation,
mbm_total_bytes monitoring
16-17 ACPI RQSC parser and init
18 Enable resctrl filesystem for Ssqosid (Kconfig)
Refer to the v3 cover letter [9] for the test setup including the
reference SoC layout and the corresponding QEMU command line.
[1] https://github.com/riscv/riscv-ssqosid/releases/tag/v1.0
[2] https://github.com/riscv-non-isa/riscv-cbqri/releases/tag/v1.0
[3] https://docs.kernel.org/filesystems/resctrl.html
[4] https://github.com/riscv-non-isa/riscv-rqsc/blob/main/src/
[5] https://git.kernel.org/pub/scm/linux/kernel/git/fustini/linux.git/log/?h=b4/ssqosid-cbqri-rqsc
[6] https://lore.kernel.org/qemu-devel/20260105-riscv-ssqosid-cbqri-v4-0-9ad7671dde78@kernel.org/
[7] https://lore.kernel.org/qemu-devel/20260202-riscv-rqsc-v1-0-dcf448a3ed73@kernel.org/
[8] https://github.com/tt-fustini/qemu/tree/b4/riscv-rqsc
[9] https://lore.kernel.org/r/20260414-ssqosid-cbqri-rqsc-v7-0-v3-0-b3b2e7e9847a@kernel.org
Key design decisions
--------------------
- Create new resource types as RDT_RESOURCE_MBA cannot represent the
semantics of the CBQRI bandwidth controllers:
- RDT_RESOURCE_MB_MIN matches CBQRI Rbwb (reserved bandwidth
blocks). The sum of Rbwb across all control groups must be
<= MRBWB (maximum number of reserved bandwidth blocks).
- RDT_RESOURCE_MB_WGHT matches CBQRI Mweight, the weighted shared of
the remaining bandwidth blocks. Values are in [0, 255]: 0 disables
work-conserving sharing for the group, 1..255 compete for the
leftover pool.
- mbm_total_bytes is supported but only on platforms that expose one
mon-capable bandwidth controller. That single BC pairs with every L3
monitoring domain on the assumption that all memory traffic flows
through it.
Open issues
-----------
- RDT_RESOURCE_MB_MIN and RDT_RESOURCE_MB_WGHT are intended to drive
discussion, not as the final solution. I plan to rebase onto
Reinette's proof of concept once it is posted.
- resctrl monitoring scope limitations:
- monitor-only L3 capacity controllers are not supported.
- CBQRI capacity controllers can monitor any cache level, but resctrl
only supports occupancy on L3.
- resctrl needs to gain a non-CPU scope level in order for
mbm_total_bytes to be supported on platforms with multiple
bandwidth controllers.
- cc_cunits is not supported. cc_block_mask maps well onto resctrl's
existing CBM schema, but there is no existing equivalent for
capacity units.
- RQSC structs live in drivers/acpi/riscv/rqsc.h until the spec is
ratified and the ACPICA upstream submission lands. They will then move
to include/acpi/actbl2.h. The spec is in the final phase
before ratification.
Changes in v4:
--------------
resctrl:
- Add RDT_RESOURCE_MB_MIN and RDT_RESOURCE_MB_WGHT
- Add default_to_min to resctrl_membw so MB_MIN defaults to min_bw
- Add L3 cache occupancy monitoring for L3-scoped capacity controllers
- Add mbm_total_bytes bandwidth monitoring when there is a single
bandwidth controller
- Move domain creation into cpuhp callbacks so that cpu_mask reflects
only online CPUs
- resctrl_arch_reset_rmid() returns early when called with IRQs
disabled.
CBQRI:
- Replace per-controller spinlock with mutex. Each CBQRI op is a
write-then-poll-busy cycle of up to 1 ms. A sleeping mutex paired
with readq_poll_timeout() keeps preemption enabled across the
busy-wait. All resctrl-arch entry points run in process context.
- Replace struct cbqri_config with direct params in helper functions.
- max_rmid = min(max_rmid, ctrl->mcid_count) now gated on
ctrl->mon_capable.
- Validate that the sum of Rbwb does not exceed MRBWB.
- Move CDP enable state from file-scope globals to per-resource
cdp_enabled / cdp_capable.
- Configure both AT_CODE and AT_DATA limits when CDP is supported but
not enabled.
Ssqosid:
- __switch_to_srmcfg() emits RISCV_FENCE(rw, o) before and (o, rw)
after csrw to drain old-task stores and order new-task loads.
- Invalidate per-cpu cpu_srmcfg on hart online via CPUHP_AP_ONLINE_DYN.
Also seed already-online CPUs synchronously at init.
ACPI:
- Drop the PPTT helper patch and resolve cache_size via cacheinfo at
cbqri_resctrl_setup() time.
- ACPI driver now calls riscv_cbqri_register_controller() and the
cbqri_controller internals stay in cbqri_internal.h.
Refer to v3 for previous change logs:
https://lore.kernel.org/r/20260414-ssqosid-cbqri-rqsc-v7-0-v3-0-b3b2e7e9847a@kernel.org
---
Drew Fustini (18):
dt-bindings: riscv: Add Ssqosid extension description
riscv: detect the Ssqosid extension
riscv: add support for srmcfg CSR from Ssqosid extension
fs/resctrl: Add resctrl_is_membw() helper
fs/resctrl: Add RDT_RESOURCE_MB_MIN and RDT_RESOURCE_MB_WGHT
fs/resctrl: Let bandwidth resources default to min_bw at reset
riscv_cbqri: Add capacity controller probe and allocation device ops
riscv_cbqri: Add capacity controller monitoring device ops
riscv_cbqri: Add bandwidth controller probe and allocation device ops
riscv_cbqri: Add bandwidth controller monitoring device ops
riscv_cbqri: resctrl: Add cache allocation via capacity block mask
riscv_cbqri: resctrl: Add L3 cache occupancy monitoring
riscv_cbqri: resctrl: Add MB_MIN bandwidth allocation via Rbwb
riscv_cbqri: resctrl: Add MB_WGHT bandwidth allocation via Mweight
riscv_cbqri: resctrl: Add mbm_total_bytes bandwidth monitoring
ACPI: RISC-V: Parse RISC-V Quality of Service Controller (RQSC) table
ACPI: RISC-V: Add support for RISC-V Quality of Service Controller (RQSC)
riscv: enable resctrl filesystem for Ssqosid
.../devicetree/bindings/riscv/extensions.yaml | 6 +
MAINTAINERS | 15 +
arch/riscv/Kconfig | 20 +
arch/riscv/include/asm/acpi.h | 10 +
arch/riscv/include/asm/csr.h | 5 +
arch/riscv/include/asm/hwcap.h | 1 +
arch/riscv/include/asm/processor.h | 3 +
arch/riscv/include/asm/qos.h | 64 +
arch/riscv/include/asm/resctrl.h | 152 +++
arch/riscv/include/asm/switch_to.h | 3 +
arch/riscv/kernel/Makefile | 2 +
arch/riscv/kernel/cpufeature.c | 1 +
arch/riscv/kernel/qos.c | 49 +
drivers/acpi/riscv/Makefile | 1 +
drivers/acpi/riscv/init.c | 21 +
drivers/acpi/riscv/rqsc.c | 147 +++
drivers/acpi/riscv/rqsc.h | 52 +
drivers/resctrl/Kconfig | 33 +
drivers/resctrl/Makefile | 6 +
drivers/resctrl/cbqri_devices.c | 1016 ++++++++++++++
drivers/resctrl/cbqri_internal.h | 240 ++++
drivers/resctrl/cbqri_resctrl.c | 1388 ++++++++++++++++++++
fs/resctrl/ctrlmondata.c | 3 +-
fs/resctrl/internal.h | 2 +
fs/resctrl/rdtgroup.c | 16 +-
include/linux/resctrl.h | 13 +-
include/linux/riscv_cbqri.h | 66 +
27 files changed, 3326 insertions(+), 9 deletions(-)
---
base-commit: ef5f46b630235b75beec43174348c3d01d6fc49a
change-id: 20260329-ssqosid-cbqri-rqsc-v7-0-b0c788bab48a
Best regards,
--
Drew Fustini <fustini@kernel.org>
^ permalink raw reply
* Re: [PATCH v13 3/4] gpio: rpmsg: add generic rpmsg GPIO driver
From: Padhi, Beleswar @ 2026-05-11 4:58 UTC (permalink / raw)
To: Mathieu Poirier, Arnaud POULIQUEN
Cc: Shenwei Wang, Andrew Lunn, Linus Walleij, Bartosz Golaszewski,
Jonathan Corbet, Rob Herring, Krzysztof Kozlowski, Conor Dooley,
Bjorn Andersson, Frank Li, Sascha Hauer, Shuah Khan,
linux-gpio@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, Pengutronix Kernel Team,
Fabio Estevam, Peng Fan, devicetree@vger.kernel.org,
linux-remoteproc@vger.kernel.org, imx@lists.linux.dev,
linux-arm-kernel@lists.infradead.org, dl-linux-imx,
Bartosz Golaszewski
In-Reply-To: <afzIABSh1xtMEGbf@p14s>
Hi Mathieu,
On 5/7/2026 10:42 PM, Mathieu Poirier wrote:
> On Tue, May 05, 2026 at 10:46:11AM +0200, Arnaud POULIQUEN wrote:
>> Hi Beleswar
>>
>> On 5/5/26 07:25, Beleswar Prasad Padhi wrote:
>>> Hi Arnaud,
>>>
>>> On 04/05/26 22:34, Arnaud POULIQUEN wrote:
>>>> Hi Beleswar,
>>>>
>>>> On 5/4/26 10:17, Beleswar Prasad Padhi wrote:
>>>>
>>> [...]
>>>
>>>>>> I may have misunderstood your solution. Could you please help me
>>>>>> understand your proposal by explaining how you would handle three
>>>>>> GPIO ports defined in the DT, considering that the endpoint
>>>>>> addresses on the Linux side can be random?
>>>>>> If I assume there is a unique endpoint on the remote side,
>>>>>> I do not understand how you can match, on the firmware side,
>>>>>> the Linux endpoint address to the GPIO port.
>>>>>
>>>>> Sure, let me take an example:
>>>>> Assumptions: 3 GPIO ports in DT, 3 endpoints in Linux (one per port),
>>>>> 1 endpoint in remote (0xd) and 1 rpmsg channel (rpmsg-io)
>>>>>
>>>>> rpmsg {
>>>>> rpmsg-io {
>>>>> #address-cells = <1>;
>>>>> #size-cells = <0>;
>>>>>
>>>>> gpio@25 {
>>>>> compatible = "rpmsg-gpio";
>>>>> reg = <25>;
>>>>> gpio-controller;
>>>>> #gpio-cells = <2>;
>>>>> #interrupt-cells = <2>;
>>>>> interrupt-controller;
>>>>> };
>>>>>
>>>>> gpio@32 {
>>>>> compatible = "rpmsg-gpio";
>>>>> reg = <32>;
>>>>> gpio-controller;
>>>>> #gpio-cells = <2>;
>>>>> #interrupt-cells = <2>;
>>>>> interrupt-controller;
>>>>> };
>>>>>
>>>>> gpio@35 {
>>>>> compatible = "rpmsg-gpio";
>>>>> reg = <35>;
>>>>> gpio-controller;
>>>>> #gpio-cells = <2>;
>>>>> #interrupt-cells = <2>;
>>>>> interrupt-controller;
>>>>> };
>>>>> };
>>>>> };
>>>>>
>>>>> Code Flow:
>>>>> 1. "rpmsg-io" channel is announced from remote firmware with unique dst
>>>>> ept = 0xd.
>>>>>
>>>>> 2. rpmsg_core.c creates the default dynamic local ept for the channel
>>>>> ept = 0x405.
>>>>>
>>>>> 3. rpmsg_core.c assigns the allocated addr to rpdev device:
>>>>> rpdev->src = 0x405 and rpdev->dst = 0xd.
>>>>>
>>>>> 4. rpmsg_gpio_channel_probe() is triggered. For *each* of the GPIO ports
>>>>> in DT, it will trigger rpmsg_gpiochip_register() which will now:
>>>>> a. Call port->ept = rpmsg_create_ept(rpdev,
>>>>> rpmsg_gpio_channel_callback,
>>>>> port,
>>>>> {rpdev.id.name,
>>>>> RPMSG_ADDR_ANY,
>>>>> RPMSG_ADDR_ANY});
>>>>> Ex- port->ept->addr = 0x408
>>>>>
>>>>> b. Prepare a 8-byte message having 2 fields:
>>>>> port->ept->addr (0x408) and port->idx (25)
>>>>>
>>>>> c. Send this message to remote firmware on default channel ept
>>>>> (0x405 -> 0xd) by:
>>>>> rpmsg_send(rpdev->ept, &message, sizeof(message));
>>>>>
>>>>> d. Remote side receives this message and creates a map of the
>>>>> linux_ept_addr to gpio_port. (0x408 <-> 25)
>>>>>
>>>>> 5. After this point, any gpio messages sent from Linux from gpio port
>>>>> endpoints (Ex- 0x408) can be decoded at remote side by looking up
>>>>> its map (Ex- map[0x408] = 25).
>>>>>
>>>>> 6. Any messages sent from remote to Linux for a particular gpio port can
>>>>> also be decoded at Linux by simply fetching the priv pointer to get
>>>>> the per-port device:
>>>>> struct rpmsg_gpio_port *port = priv;
>>>>>
>>>> Thanks for the details!
>>>>
>>>> To sum up:
>>>> - the default endpoint acts as the GPIO controller (0x405),
>>>> - one extra Linux endpoint is created per port defined in DT.
>>>>
>>>> This should work, but my concerns remain the same:
>>>>
>>>> 1) This implementation forces the remote processor to handle a single
>>>> endpoint instead of one endpoint per port. This may add complexity to
>>>> the remote firmware if each port is managed in a separate thread.
>>>
>>> A. Not really, I just chose 1 remote endpoint for this example as you
>>> suggested to. We can scale it for two-way communication via the
>>> get_config message like you suggested below.
>>>
>>> B. Isn't it a bad design of the firmware if it is handling 10 gpio ports
>>> in 10 threads? The logic to handle all the ports is the same, only
>>> the parameters (e.g. line number, msg) is different.
>>>
>>>> 2) Linux, as a consumer, should not expose its capabilities to the remote
>>>> side (in your proposal it enumerates the ports defined in the DT). In my view, the remote processor should expose its capabilities as the
>>>> provider.
>>>
>>> Agreed on this.
>>>
>>>> From my perspective, based on your proposal:
>>>> 1) Linux should send a get_config message to the remote proc (0x405 -> 0xD). 2) The remote processor would respond with the list of ports, associated
>>>> with an remote endpoint addresses.
>>>
>>> Agreed, we can scale it for multiple remote endpoints like this.
>>>
>>>> 3) Linux would parse the response, compare it with the DT, enable the GPIO
>>>> ports accordingly, creating it local endpoint and associating it with
>>>> the remote endpoint.
>>>> Using name service to identify the ports should avoid step 1 & 2 ...
>>>
>>> Yes, but won't that make a lot of hard-codings in the driver?
>>>
>>> +static struct rpmsg_device_id rpmsg_gpio_channel_id_table[] = {
>>> + { .name = "rpmsg-io-25" },
>>> + { .name = "rpmsg-io-32" },
>>> + { .name = "rpmsg-io-35" },
>>> + { },
>>> +};
>>>
>>> What if tomorrow another vendor decides to add more remoteproc
>>> controlled GPIO ports to Linux, they would have to update this struct in
>>> the driver everytime. And the port indexes (25/32/35) could also differ
>>> between vendors. We should make the driver dynamic i.e. vendor
>>> agnostic.
>>>
>>> I think querying the remote firmware at runtime (step 1 & 2 above) is a
>>> common design pattern and makes the driver vendor agnostic. But feel
>>> free to correct me.
>>>
>> You are right. My proposal would require a patch in rpmsg-core. The idea of
>> allowing a postfix in the compatible string has been discussed before, but,
>> if I remember correctly, it was not concluded.
>>
> I also remember discussing this. I even reviewed one of Arnaud's patch
> and submitted one myself. This must have been in 2020 and the reason why it
> wasn't merged has escaped my memory.
>
>> /* rpmsg devices and drivers are matched using the service name */
>> static inline int rpmsg_id_match(const struct rpmsg_device *rpdev,
>> const struct rpmsg_device_id *id)
>> {
>> size_t len;
>>
>> + len = strnlen(id->name, RPMSG_NAME_SIZE);
>> + if (len && id->name[len - 1] == '*')
>> + return !strncmp(id->name, rpdev->id.name, len - 1);
>>
>> return strncmp(id->name, rpdev->id.name, RPMSG_NAME_SIZE) == 0;
>> }
>>
>> Then, in rpmsg-gpio, and possibly in other drivers such as rpmsg-tty and
>> a future rpmsg-i2c, we could use:
>> static struct rpmsg_device_id rpmsg_gpio_channel_id_table[] = {
>> { .name = "rpmsg-io" },
>> { .name = "rpmsg-io-*" },
>> { },
>> };
> That was my initial approach. We don't even need an additional "rpmsg-io-*" in
> rpmsg_gpio_channel_id_table[]. All we need is:
>
> /* rpmsg devices and drivers are matched using the service name */
> static inline int rpmsg_id_match(const struct rpmsg_device *rpdev,
> const struct rpmsg_device_id *id)
> {
> + size_t len = strnlen(id->name, RPMSG_NAME_SIZE);
>
> - return strncmp(id->name, rpdev->id.name, RPMSG_NAME_SIZE) == 0;
> + return strncmp(id->name, rpdev->id.name, len) == 0;
> }
This wildcard channel matching is interesting. It would be good to know
the reasons/cons why this patch was not concluded.
>
> And let the rpmsg-virtio-gpio driver parse @rpdev->id.name to match with a
> GPIO controller in the DT.
>
>> If exact name matching is strongly required, then this proposal would not be
>> suitablea.
>>
>> A third option would be a combination of both approaches: instantiate the
>> device using the same name service from the remote side, as done in
>> rpmsg-tty. In that case, a get_config message, or a similar mechanism, would
>> also be needed to retrieve the port information from the remote side.
>>
> I'm not overly fond of a get_config message because it is one more thing we
> have to define and maintain.
>
> Arnaud: is there a get_config message already defined for rpmsg_tty?
>
> Beleswar: Can you provide a link to a virtio device that would use a get_config
> message?
VirtIO typically uses the feature bits for negotiation and discovery.
And such a get_config message would not be needed in VirtIO layer, as
there is no multiplexing. It's a 1:1 mapping of device to driver
instance.
Thanks,
Beleswar
[...]
^ permalink raw reply
* Re: [RFC v2 0/2] add kconfirm
From: Demi Marie Obenour @ 2026-05-11 4:24 UTC (permalink / raw)
To: Julian Braha, nathan, nsc
Cc: jani.nikula, akpm, gary, ljs, arnd, gregkh, masahiroy, ojeda,
corbet, qingfang.deng, linux-kernel, rust-for-linux, linux-doc,
linux-kbuild
In-Reply-To: <20260509203808.1142311-1-julianbraha@gmail.com>
[-- Attachment #1.1.1: Type: text/plain, Size: 6508 bytes --]
On 5/9/26 16:38, Julian Braha wrote:
> Hi all,
>
> kconfirm is a tool to detect misusage of Kconfig. It detects dead code,
> constant conditions, and invalid (reverse) ranges. There are also optional
> checks to detect config options that select visible config options, and to
> check for dead links in the help texts.
>
> The full patchset (with the vendored dependencies) is available in my
> linux fork, git branch 'kconfirm_rfc2', and is based on linux v7.1-rc2:
> https://github.com/julianbraha/linux/tree/kconfirm_rfc2
>
> The patches sent here with the RFC include everything other than the
> vendored dependencies, including the tool's code, the documentation, and
> the makefile changes.
>
> Following this discussion:
> https://lore.kernel.org/all/20260405122749.4990dcb538d457769a3276e0@linux-foundation.org/
> in which Andrew brought up the possibility of moving kconfirm in-tree,
> I've prepared this RFC to do so. See also kconfirm's introduction to the
> mailing list:
> https://lore.kernel.org/all/6ec4df6d-1445-48ca-8f54-1d1a83c4716d@gmail.com/
>
> False Alarms:
> kconfirm aims for zero false-positives, which is currently true for the
> default checks (as far as I'm aware - but there are hundreds to go
> through); this is not really possible for dead link checks, as this
> depends on an internet connection, and we do not attempt to bypass bot
> blocks. For this reason, dead link checking is disabled by default, but
> I've provided an example below of how to enable it. Additionally, you can
> view my previous message to the mailing list with hand-verified dead links
> here:
> https://lore.kernel.org/all/6732bf08-41ee-40c4-83b2-4ae8bc0da7cf@gmail.com/
>
> Additionally, there is an optional check to detect config options that
> select visible config options, as requested by Jani during the review of
> the first version of this RFC:
> https://lore.kernel.org/all/dcb7439832f0bb35598fba653d922b5f6a4d0058@intel.com/
>
> Even after deduplicating across architectures, there are well over 1,000
> instances of these select-visible cases, and I suspect that, despite the
> Kconfig documentation saying select-visible should be avoided, some
> exceptions will be made. So, I have left this check disabled by default,
> keeping in line with the goal of having a low-noise checker. If interested
> in using it, I have included an example below of how to enable this check.
>
> Current State of Alarms:
> On Linux v7.1-rc2 (which this RFC is based), there are 489 alarms coming
> from the default set of checks, and an additional 1,789 alarms if enabling
> the optional select-visible check. These counts are with deduplication
> across architectures, a change that was made to the tool's CLI from RFC v1
> to RFC v2. The last time I checked linux-next (next-20260427), there were
> 81 unique dead links.
>
> The most critical check is the dead default statements, which has surfaced
> a few misconfiguration bugs (fortunately, just for kunit tests), see
> examples:
> https://lore.kernel.org/all/20260323124118.1414913-1-julianbraha@gmail.com/
> and:
> https://lore.kernel.org/all/20260323123536.1413732-1-julianbraha@gmail.com/
>
> But hopefully kconfirm can ease maintenance and we can prevent more of
> these from making it into the tree in the future.
>
> Use it:
> You can test out kconfirm with this patch series by compiling and running
> kconfirm like this:
>
> `make kconfirm`
>
> To enable the select-visible check:
> `KCONFIRM_ARGS="--enable select_visible" make kconfirm`
>
> And to enable dead link checks in the help texts:
> `KCONFIRM_ARGS="--enable dead_links" make kconfirm`
>
> Note that it is not architecture-specific; it runs tree-wide. Any alarms
> that are specific to one or more architectures will have a tag using the
> config option(s) of the architecture(s), for example: [X86] or [X86, ARM]
>
> The dependencies are vendored in scripts/kconfirm/vendor so that no
> internet connection is needed to compile the code. The total size of the
> tool with dependencies is 49mb, making it a large amount of code, though
> still in the ballpark of perf, at 42mb.
>
> I managed to reduce the size of the vendored dependencies from 264mb by
> taking multiple approaches:
> 1. Removed 'rustls' for TLS and instead use the user's system OpenSSL
> 2. Replaced the 'reqwest' crate with the smaller 'ureq' crate
> 3. Disabled the default features of the dependencies, and only enabled
> whatever is needed by kconfirm
> 3. Filtered out various things from the vendored dependencies unneeded for
> compilation (e.g. docs & tests for dependencies)
> 4. Filtered out platform-specific code that isn't needed for linux
> developers (e.g. Nintendo 3DS)
>
> The script I ran to generate the vendored dependencies with filtering is
> available in scripts/kconfirm/vendor_dependencies.sh
>
> Requested feedback:
> 1. I would like to know if anyone thinks that the select-visible check
> should be enabled by default.
> 2. The only "person" that commented on `make clean` deleting the compiled
> kconfirm binary/artifacts was sashiko-bot. Now, there is just
> `make kconfirmclean` for deleting 'scripts/kconfirm/release/', and
> `make clean` no longer touches kconfirm. Please let me know if anyone has
> requested changes on the integration with Make.
>
> Thanks,
> Julian Braha
> ---
> Changes since v1:
> - vendored dependencies instead of requiring an internet connection
> - removed Cargo.lock
> - replaced reqwest dependency with smaller ureq
> - removed rustls, expect user to have openssl instead
> - added select-visible check based on Jani's feature request
> - added invalid (reverse) range check
> - deduplicating alarms that appear for multiple architectures
> - `make clean` no longer deletes kconfirm's build artifacts
> - typo fixes in documentation
> - added patch description for the main "add kconfirm" patch (patch 1/2)
>
> Link to v1:
> https://lore.kernel.org/all/20260427174429.779474-1-julianbraha@gmail.com/
> ---
This adds too many dependencies.
Some suggestions:
- Use system libcurl instead of ureq.
- Use libc getopt_long instead of clap.
- Use manual FFI bindings instead of third-party crates.
- Use the C Kconfig parser instead of a third-party library.
Ideally, this shouldn't need any dependencies from crates.io
at all.
--
Sincerely,
Demi Marie Obenour (she/her/hers)
[-- Attachment #1.1.2: OpenPGP public key --]
[-- Type: application/pgp-keys, Size: 7253 bytes --]
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply
* [PATCH v13 14/15] arm64: kexec: Add support for crashkernel CMA reservation
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
Commit 35c18f2933c5 ("Add a new optional ",cma" suffix to the
crashkernel= command line option") and commit ab475510e042 ("kdump:
implement reserve_crashkernel_cma") added CMA support for kdump
crashkernel reservation.
Crash kernel memory reservation wastes production resources if too
large, risks kdump failure if too small, and faces allocation difficulties
on fragmented systems due to contiguous block constraints. The new
CMA-based crashkernel reservation scheme splits the "large fixed
reservation" into a "small fixed region + large CMA dynamic region": the
CMA memory is available to userspace during normal operation to avoid
waste, and is reclaimed for kdump upon crash—saving memory while
improving reliability.
So extend crashkernel CMA reservation support to arm64. The following
changes are made to enable CMA reservation:
- Parse and obtain the CMA reservation size along with other crashkernel
parameters.
- Call reserve_crashkernel_cma() to allocate the CMA region for kdump.
- Include the CMA-reserved ranges for kdump kernel to use.
- Exclude the CMA-reserved ranges from the crash kernel memory to
prevent them from being exported through /proc/vmcore, which is already
done in the crash core.
Update kernel-parameters.txt to document CMA support for crashkernel on
arm64 architecture.
Tested-by: Breno Leitao <leitao@debian.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
v7:
- Correct the inclusion of CMA-reserved ranges for kdump
kernel in of/kexec.
v3:
- Add Acked-by.
v2:
- Free cmem in prepare_elf_headers()
- Add the mtivation.
---
Documentation/admin-guide/kernel-parameters.txt | 2 +-
arch/arm64/kernel/machine_kexec_file.c | 2 +-
arch/arm64/mm/init.c | 5 +++--
drivers/of/fdt.c | 9 +++++----
drivers/of/kexec.c | 9 +++++++++
include/linux/crash_reserve.h | 4 +++-
6 files changed, 22 insertions(+), 9 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4d0f545fb3ec..52742fab49a9 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1119,7 +1119,7 @@ Kernel parameters
It will be ignored when crashkernel=X,high is not used
or memory reserved is below 4G.
crashkernel=size[KMG],cma
- [KNL, X86, ppc] Reserve additional crash kernel memory from
+ [KNL, X86, ARM64, PPC] Reserve additional crash kernel memory from
CMA. This reservation is usable by the first system's
userspace memory and kernel movable allocations (memory
balloon, zswap). Pages allocated from this memory range
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index 8d72038f206d..0590ff9eeab4 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -42,7 +42,7 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
#ifdef CONFIG_CRASH_DUMP
unsigned int arch_get_system_nr_ranges(void)
{
- unsigned int nr_ranges = 2; /* for exclusion of crashkernel region */
+ unsigned int nr_ranges = 2 + crashk_cma_cnt; /* for exclusion of crashkernel region */
phys_addr_t start, end;
u64 i;
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 97987f850a33..227f58522dad 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -96,8 +96,8 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit;
static void __init arch_reserve_crashkernel(void)
{
+ unsigned long long crash_base, crash_size, cma_size = 0;
unsigned long long low_size = 0;
- unsigned long long crash_base, crash_size;
bool high = false;
int ret;
@@ -106,11 +106,12 @@ static void __init arch_reserve_crashkernel(void)
ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
&crash_size, &crash_base,
- &low_size, NULL, &high);
+ &low_size, &cma_size, &high);
if (ret)
return;
reserve_crashkernel_generic(crash_size, crash_base, low_size, high);
+ reserve_crashkernel_cma(cma_size);
}
static phys_addr_t __init max_zone_phys(phys_addr_t zone_limit)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 82f7327c59ea..0470acbd1fcf 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -880,11 +880,12 @@ static unsigned long chosen_node_offset = -FDT_ERR_NOTFOUND;
/*
* The main usage of linux,usable-memory-range is for crash dump kernel.
* Originally, the number of usable-memory regions is one. Now there may
- * be two regions, low region and high region.
- * To make compatibility with existing user-space and older kdump, the low
- * region is always the last range of linux,usable-memory-range if exist.
+ * be 2 + CRASHK_CMA_RANGES_MAX regions, low region, high region and cma
+ * regions. To make compatibility with existing user-space and older kdump,
+ * the high and low region are always the first two ranges of
+ * linux,usable-memory-range if exist.
*/
-#define MAX_USABLE_RANGES 2
+#define MAX_USABLE_RANGES (2 + CRASHK_CMA_RANGES_MAX)
/**
* early_init_dt_check_for_usable_mem_range - Decode usable memory range
diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index b6837e299e7f..029903b986cb 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -458,6 +458,15 @@ void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
if (ret)
goto out;
}
+
+ for (int i = 0; i < crashk_cma_cnt; i++) {
+ ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
+ "linux,usable-memory-range",
+ crashk_cma_ranges[i].start,
+ crashk_cma_ranges[i].end - crashk_cma_ranges[i].start + 1);
+ if (ret)
+ goto out;
+ }
#endif
}
diff --git a/include/linux/crash_reserve.h b/include/linux/crash_reserve.h
index f0dc03d94ca2..30864d90d7f5 100644
--- a/include/linux/crash_reserve.h
+++ b/include/linux/crash_reserve.h
@@ -14,9 +14,11 @@
extern struct resource crashk_res;
extern struct resource crashk_low_res;
extern struct range crashk_cma_ranges[];
+
+#define CRASHK_CMA_RANGES_MAX 4
#if defined(CONFIG_CMA) && defined(CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION)
#define CRASHKERNEL_CMA
-#define CRASHKERNEL_CMA_RANGES_MAX 4
+#define CRASHKERNEL_CMA_RANGES_MAX (CRASHK_CMA_RANGES_MAX)
extern int crashk_cma_cnt;
#else
#define crashk_cma_cnt 0
--
2.34.1
^ permalink raw reply related
* [PATCH v13 15/15] riscv: kexec: Add support for crashkernel CMA reservation
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
Commit 35c18f2933c5 ("Add a new optional ",cma" suffix to the
crashkernel= command line option") and commit ab475510e042 ("kdump:
implement reserve_crashkernel_cma") added CMA support for kdump
crashkernel reservation. This allows the kernel to dynamically allocate
contiguous memory for crash dumping when needed, rather than permanently
reserving a fixed region at boot time.
So extend crashkernel CMA reservation support to riscv. The following
changes are made to enable CMA reservation:
- Parse and obtain the CMA reservation size along with other crashkernel
parameters.
- Call reserve_crashkernel_cma() to allocate the CMA region for kdump.
- Include the CMA-reserved ranges for kdump kernel to use, which was
already done in of_kexec_alloc_and_setup_fdt().
- Exclude the CMA-reserved ranges from the crash kernel memory to
prevent them from being exported through /proc/vmcore, which was
already done in the crash core.
Update kernel-parameters.txt to document CMA support for crashkernel on
riscv architecture.
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Paul Walmsley <pjw@kernel.org> # arch/riscv
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++--------
arch/riscv/kernel/machine_kexec_file.c | 2 +-
arch/riscv/mm/init.c | 5 +++--
3 files changed, 12 insertions(+), 11 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 52742fab49a9..3ff3ddd516cf 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1119,14 +1119,14 @@ Kernel parameters
It will be ignored when crashkernel=X,high is not used
or memory reserved is below 4G.
crashkernel=size[KMG],cma
- [KNL, X86, ARM64, PPC] Reserve additional crash kernel memory from
- CMA. This reservation is usable by the first system's
- userspace memory and kernel movable allocations (memory
- balloon, zswap). Pages allocated from this memory range
- will not be included in the vmcore so this should not
- be used if dumping of userspace memory is intended and
- it has to be expected that some movable kernel pages
- may be missing from the dump.
+ [KNL, X86, ARM64, RISCV, PPC] Reserve additional crash
+ kernel memory from CMA. This reservation is usable by
+ the first system's userspace memory and kernel movable
+ allocations (memory balloon, zswap). Pages allocated
+ from this memory range will not be included in the vmcore
+ so this should not be used if dumping of userspace memory
+ is intended and it has to be expected that some movable
+ kernel pages may be missing from the dump.
A standard crashkernel reservation, as described above,
is still needed to hold the crash kernel and initrd.
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index bea818f75dd6..c79cd86d5713 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -46,7 +46,7 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
unsigned int arch_get_system_nr_ranges(void)
{
- unsigned int nr_ranges = 2; /* For exclusion of crashkernel region */
+ unsigned int nr_ranges = 2 + crashk_cma_cnt; /* For exclusion of crashkernel region */
walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index decd7df40fa4..c848454b8349 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -1295,7 +1295,7 @@ static inline void setup_vm_final(void)
*/
static void __init arch_reserve_crashkernel(void)
{
- unsigned long long low_size = 0;
+ unsigned long long low_size = 0, cma_size = 0;
unsigned long long crash_base, crash_size;
bool high = false;
int ret;
@@ -1305,11 +1305,12 @@ static void __init arch_reserve_crashkernel(void)
ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
&crash_size, &crash_base,
- &low_size, NULL, &high);
+ &low_size, &cma_size, &high);
if (ret)
return;
reserve_crashkernel_generic(crash_size, crash_base, low_size, high);
+ reserve_crashkernel_cma(cma_size);
}
void __init paging_init(void)
--
2.34.1
^ permalink raw reply related
* [PATCH v13 13/15] crash: Use crash_exclude_core_ranges() on powerpc
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
The crash memory exclude of crashk_res and crashk_cma memory on powerpc
are almost identical to the generic crash_exclude_core_ranges().
By introducing the architecture-specific arch_crash_exclude_mem_range()
function with a default implementation of crash_exclude_mem_range(),
and using crash_exclude_mem_range_guarded as powerpc's separate
implementation, the generic crash_exclude_core_ranges() helper function
can be reused.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/powerpc/include/asm/kexec_ranges.h | 3 ---
arch/powerpc/kexec/crash.c | 2 +-
arch/powerpc/kexec/ranges.c | 16 ++++------------
include/linux/crash_core.h | 4 ++++
kernel/crash_core.c | 19 +++++++++++++------
5 files changed, 22 insertions(+), 22 deletions(-)
diff --git a/arch/powerpc/include/asm/kexec_ranges.h b/arch/powerpc/include/asm/kexec_ranges.h
index ad95e3792d10..8489e844b447 100644
--- a/arch/powerpc/include/asm/kexec_ranges.h
+++ b/arch/powerpc/include/asm/kexec_ranges.h
@@ -7,9 +7,6 @@
void sort_memory_ranges(struct crash_mem *mrngs, bool merge);
struct crash_mem *realloc_mem_ranges(struct crash_mem **mem_ranges);
int add_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size);
-int crash_exclude_mem_range_guarded(struct crash_mem **mem_ranges,
- unsigned long long mstart,
- unsigned long long mend);
int get_exclude_memory_ranges(struct crash_mem **mem_ranges);
int get_reserved_memory_ranges(struct crash_mem **mem_ranges);
int get_crash_memory_ranges(struct crash_mem **mem_ranges);
diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c
index d634db67becc..775895f31037 100644
--- a/arch/powerpc/kexec/crash.c
+++ b/arch/powerpc/kexec/crash.c
@@ -513,7 +513,7 @@ static void update_crash_elfcorehdr(struct kimage *image, struct memory_notify *
base_addr = PFN_PHYS(mn->start_pfn);
size = mn->nr_pages * PAGE_SIZE;
end = base_addr + size - 1;
- ret = crash_exclude_mem_range_guarded(&cmem, base_addr, end);
+ ret = arch_crash_exclude_mem_range(&cmem, base_addr, end);
if (ret) {
pr_err("Failed to remove hot-unplugged memory from crash memory ranges\n");
goto out;
diff --git a/arch/powerpc/kexec/ranges.c b/arch/powerpc/kexec/ranges.c
index 6c58bcc3e130..e5fea23b191b 100644
--- a/arch/powerpc/kexec/ranges.c
+++ b/arch/powerpc/kexec/ranges.c
@@ -553,9 +553,9 @@ int get_usable_memory_ranges(struct crash_mem **mem_ranges)
#endif /* CONFIG_KEXEC_FILE */
#ifdef CONFIG_CRASH_DUMP
-int crash_exclude_mem_range_guarded(struct crash_mem **mem_ranges,
- unsigned long long mstart,
- unsigned long long mend)
+int arch_crash_exclude_mem_range(struct crash_mem **mem_ranges,
+ unsigned long long mstart,
+ unsigned long long mend)
{
struct crash_mem *tmem = *mem_ranges;
@@ -604,18 +604,10 @@ int get_crash_memory_ranges(struct crash_mem **mem_ranges)
sort_memory_ranges(*mem_ranges, true);
}
- /* Exclude crashkernel region */
- ret = crash_exclude_mem_range_guarded(mem_ranges, crashk_res.start, crashk_res.end);
+ ret = crash_exclude_core_ranges(mem_ranges);
if (ret)
goto out;
- for (i = 0; i < crashk_cma_cnt; ++i) {
- ret = crash_exclude_mem_range_guarded(mem_ranges, crashk_cma_ranges[i].start,
- crashk_cma_ranges[i].end);
- if (ret)
- goto out;
- }
-
/*
* FIXME: For now, stay in parity with kexec-tools but if RTAS/OPAL
* regions are exported to save their context at the time of
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 583ffcc703d4..bc087124cd78 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -61,6 +61,7 @@ extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_ma
void **addr, unsigned long *sz);
extern int crash_prepare_headers(int need_kernel_map, void **addr,
unsigned long *sz, unsigned long *nr_mem_ranges);
+extern int crash_exclude_core_ranges(struct crash_mem **cmem);
struct kimage;
struct kexec_segment;
@@ -81,6 +82,9 @@ extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
extern unsigned int arch_get_system_nr_ranges(void);
extern int arch_crash_populate_cmem(struct crash_mem *cmem);
extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
+extern int arch_crash_exclude_mem_range(struct crash_mem **mem,
+ unsigned long long mstart,
+ unsigned long long mend);
#else /* !CONFIG_CRASH_DUMP*/
struct pt_regs;
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index d28be3890efb..c42eeabcbdac 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -286,24 +286,31 @@ unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
-static int crash_exclude_core_ranges(struct crash_mem *cmem)
+int __weak arch_crash_exclude_mem_range(struct crash_mem **mem,
+ unsigned long long mstart,
+ unsigned long long mend)
+{
+ return crash_exclude_mem_range(*mem, mstart, mend);
+}
+
+int crash_exclude_core_ranges(struct crash_mem **cmem)
{
int ret, i;
/* Exclude crashkernel region */
- ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
+ ret = arch_crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
if (ret)
return ret;
if (crashk_low_res.end) {
- ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
+ ret = arch_crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
if (ret)
return ret;
}
for (i = 0; i < crashk_cma_cnt; ++i) {
- ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
- crashk_cma_ranges[i].end);
+ ret = arch_crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
+ crashk_cma_ranges[i].end);
if (ret)
return ret;
}
@@ -338,7 +345,7 @@ int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
}
put_online_mems();
- ret = crash_exclude_core_ranges(cmem);
+ ret = crash_exclude_core_ranges(&cmem);
if (ret)
goto out;
--
2.34.1
^ permalink raw reply related
* [PATCH v13 12/15] LoongArch: kexec: Use crash_prepare_headers() helper to simplify code
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
Use the newly introduced crash_prepare_headers() function to replace
the existing prepare_elf_headers(), allocate cmem and exclude crash kernel
memory in the crash core, which reduce code duplication.
Only the following two architecture functions need to be implemented:
- arch_get_system_nr_ranges(). Use for_each_mem_range to traverse
and pre-count the max number of memory ranges.
- arch_crash_populate_cmem(). Use for_each_mem_range to traverse
and collect the memory ranges and fills them into cmem.
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Youling Tang <tangyouling@kylinos.cn>
Cc: Baoquan He <bhe@redhat.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/loongarch/kernel/machine_kexec_file.c | 46 +++++++---------------
1 file changed, 14 insertions(+), 32 deletions(-)
diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
index 167392c1da33..3d0386ee18ef 100644
--- a/arch/loongarch/kernel/machine_kexec_file.c
+++ b/arch/loongarch/kernel/machine_kexec_file.c
@@ -56,51 +56,33 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
}
#ifdef CONFIG_CRASH_DUMP
-
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+unsigned int arch_get_system_nr_ranges(void)
{
- int ret, nr_ranges;
- uint64_t i;
+ int nr_ranges = 2; /* for exclusion of crashkernel region */
phys_addr_t start, end;
- struct crash_mem *cmem;
+ uint64_t i;
- nr_ranges = 2; /* for exclusion of crashkernel region */
for_each_mem_range(i, &start, &end)
nr_ranges++;
- cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
- if (!cmem)
- return -ENOMEM;
+ return nr_ranges;
+}
+
+int arch_crash_populate_cmem(struct crash_mem *cmem)
+{
+ phys_addr_t start, end;
+ uint64_t i;
- cmem->max_nr_ranges = nr_ranges;
- cmem->nr_ranges = 0;
for_each_mem_range(i, &start, &end) {
- if (cmem->nr_ranges >= cmem->max_nr_ranges) {
- ret = -ENOMEM;
- goto out;
- }
+ if (cmem->nr_ranges >= cmem->max_nr_ranges)
+ return -ENOMEM;
cmem->ranges[cmem->nr_ranges].start = start;
cmem->ranges[cmem->nr_ranges].end = end - 1;
cmem->nr_ranges++;
}
- /* Exclude crashkernel region */
- ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
- if (ret < 0)
- goto out;
-
- if (crashk_low_res.end) {
- ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
- if (ret < 0)
- goto out;
- }
-
- ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
- kfree(cmem);
- return ret;
+ return 0;
}
/*
@@ -168,7 +150,7 @@ int load_other_segments(struct kimage *image,
void *headers;
unsigned long headers_sz;
- ret = prepare_elf_headers(&headers, &headers_sz);
+ ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
if (ret < 0) {
pr_err("Preparing elf core header failed\n");
goto out_err;
--
2.34.1
^ permalink raw reply related
* [PATCH v13 09/15] arm64: kexec_file: Use crash_prepare_headers() helper to simplify code
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
Use the newly introduced crash_prepare_headers() function to replace
the existing prepare_elf_headers(), allocate cmem and exclude crash
kernel memory in the crash core, which reduce code duplication.
Only the following two architecture functions need to be implemented:
- arch_get_system_nr_ranges(). Use for_each_mem_range() to traverse
and pre-count the max number of memory ranges.
- arch_crash_populate_cmem(). Use for_each_mem_range to traverse
and collect the memory ranges and fills them into cmem.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/arm64/kernel/machine_kexec_file.c | 46 ++++++++------------------
1 file changed, 14 insertions(+), 32 deletions(-)
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index a67e7b1abbab..8d72038f206d 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -40,51 +40,33 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
}
#ifdef CONFIG_CRASH_DUMP
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+unsigned int arch_get_system_nr_ranges(void)
{
- struct crash_mem *cmem;
- unsigned int nr_ranges;
- int ret;
- u64 i;
+ unsigned int nr_ranges = 2; /* for exclusion of crashkernel region */
phys_addr_t start, end;
+ u64 i;
- nr_ranges = 2; /* for exclusion of crashkernel region */
for_each_mem_range(i, &start, &end)
nr_ranges++;
- cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
- if (!cmem)
- return -ENOMEM;
+ return nr_ranges;
+}
+
+int arch_crash_populate_cmem(struct crash_mem *cmem)
+{
+ phys_addr_t start, end;
+ u64 i;
- cmem->max_nr_ranges = nr_ranges;
- cmem->nr_ranges = 0;
for_each_mem_range(i, &start, &end) {
- if (cmem->nr_ranges >= cmem->max_nr_ranges) {
- ret = -ENOMEM;
- goto out;
- }
+ if (cmem->nr_ranges >= cmem->max_nr_ranges)
+ return -ENOMEM;
cmem->ranges[cmem->nr_ranges].start = start;
cmem->ranges[cmem->nr_ranges].end = end - 1;
cmem->nr_ranges++;
}
- /* Exclude crashkernel region */
- ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
- if (ret)
- goto out;
-
- if (crashk_low_res.end) {
- ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
- if (ret)
- goto out;
- }
-
- ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
- kfree(cmem);
- return ret;
+ return 0;
}
#endif
@@ -114,7 +96,7 @@ int load_other_segments(struct kimage *image,
void *headers;
unsigned long headers_sz;
if (image->type == KEXEC_TYPE_CRASH) {
- ret = prepare_elf_headers(&headers, &headers_sz);
+ ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
if (ret) {
pr_err("Preparing elf core header failed\n");
goto out_err;
--
2.34.1
^ permalink raw reply related
* [PATCH v13 11/15] riscv: kexec_file: Use crash_prepare_headers() helper to simplify code
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
Use the newly introduced crash_prepare_headers() function to replace
the existing prepare_elf_headers(), allocate cmem and exclude crash kernel
memory in the crash core, which reduce code duplication.
Only the following two architecture functions need to be implemented:
- arch_get_system_nr_ranges(). Call get_nr_ram_ranges_callback()
to pre-counts the max number of memory ranges.
- arch_crash_populate_cmem(). Use prepare_elf64_ram_headers_callback()
to collects the memory ranges and fills them into cmem.
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/riscv/kernel/machine_kexec_file.c | 47 +++++++-------------------
1 file changed, 12 insertions(+), 35 deletions(-)
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index 773a1cba8ba0..bea818f75dd6 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -44,6 +44,15 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
return 0;
}
+unsigned int arch_get_system_nr_ranges(void)
+{
+ unsigned int nr_ranges = 2; /* For exclusion of crashkernel region */
+
+ walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
+
+ return nr_ranges;
+}
+
static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
{
struct crash_mem *cmem = arg;
@@ -58,41 +67,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
return 0;
}
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+int arch_crash_populate_cmem(struct crash_mem *cmem)
{
- struct crash_mem *cmem;
- unsigned int nr_ranges;
- int ret;
-
- nr_ranges = 2; /* For exclusion of crashkernel region */
- walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
-
- cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
- if (!cmem)
- return -ENOMEM;
-
- cmem->max_nr_ranges = nr_ranges;
- cmem->nr_ranges = 0;
- ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
- if (ret)
- goto out;
-
- /* Exclude crashkernel region */
- ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
- if (ret)
- goto out;
-
- if (crashk_low_res.end) {
- ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
- if (ret)
- goto out;
- }
-
- ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
- kfree(cmem);
- return ret;
+ return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
}
static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
@@ -284,7 +261,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
if (image->type == KEXEC_TYPE_CRASH) {
void *headers;
unsigned long headers_sz;
- ret = prepare_elf_headers(&headers, &headers_sz);
+ ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
if (ret) {
pr_err("Preparing elf core header failed\n");
goto out;
--
2.34.1
^ permalink raw reply related
* [PATCH v13 07/15] powerpc/crash: sort crash memory ranges before preparing elfcorehdr
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
From: Sourabh Jain <sourabhjain@linux.ibm.com>
During a memory hot-remove event, the elfcorehdr is rebuilt to exclude
the removed memory. While updating the crash memory ranges for this
operation, the crash memory ranges array can become unsorted. This
happens because remove_mem_range() may split a memory range into two
parts and append the higher-address part as a separate range at the end
of the array.
So far, no issues have been observed due to the unsorted crash memory
ranges. However, this could lead to problems once crash memory range
removal is handled by generic code, as introduced in the upcoming
patches in this series.
Currently, powerpc uses a platform-specific function,
remove_mem_range(), to exclude hot-removed memory from the crash memory
ranges. This function performs the same task as the generic
crash_exclude_mem_range() in crash_core.c. The generic helper also
ensures that the crash memory ranges remain sorted. So remove the
redundant powerpc-specific implementation and instead call
crash_exclude_mem_range_guarded() (which internally calls
crash_exclude_mem_range()) to exclude the hot-removed memory ranges.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan he <bhe@redhat.com>
Cc: Jinjie Ruan <ruanjinjie@huawei.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Cc: linux-kernel@vger.kernel.org
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/powerpc/include/asm/kexec_ranges.h | 4 +-
arch/powerpc/kexec/crash.c | 5 +-
arch/powerpc/kexec/ranges.c | 87 +------------------------
3 files changed, 7 insertions(+), 89 deletions(-)
diff --git a/arch/powerpc/include/asm/kexec_ranges.h b/arch/powerpc/include/asm/kexec_ranges.h
index 14055896cbcb..ad95e3792d10 100644
--- a/arch/powerpc/include/asm/kexec_ranges.h
+++ b/arch/powerpc/include/asm/kexec_ranges.h
@@ -7,7 +7,9 @@
void sort_memory_ranges(struct crash_mem *mrngs, bool merge);
struct crash_mem *realloc_mem_ranges(struct crash_mem **mem_ranges);
int add_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size);
-int remove_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size);
+int crash_exclude_mem_range_guarded(struct crash_mem **mem_ranges,
+ unsigned long long mstart,
+ unsigned long long mend);
int get_exclude_memory_ranges(struct crash_mem **mem_ranges);
int get_reserved_memory_ranges(struct crash_mem **mem_ranges);
int get_crash_memory_ranges(struct crash_mem **mem_ranges);
diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c
index a520f851c3a6..d634db67becc 100644
--- a/arch/powerpc/kexec/crash.c
+++ b/arch/powerpc/kexec/crash.c
@@ -493,7 +493,7 @@ static void update_crash_elfcorehdr(struct kimage *image, struct memory_notify *
struct crash_mem *cmem = NULL;
struct kexec_segment *ksegment;
void *ptr, *mem, *elfbuf = NULL;
- unsigned long elfsz, memsz, base_addr, size;
+ unsigned long elfsz, memsz, base_addr, size, end;
ksegment = &image->segment[image->elfcorehdr_index];
mem = (void *) ksegment->mem;
@@ -512,7 +512,8 @@ static void update_crash_elfcorehdr(struct kimage *image, struct memory_notify *
if (image->hp_action == KEXEC_CRASH_HP_REMOVE_MEMORY) {
base_addr = PFN_PHYS(mn->start_pfn);
size = mn->nr_pages * PAGE_SIZE;
- ret = remove_mem_range(&cmem, base_addr, size);
+ end = base_addr + size - 1;
+ ret = crash_exclude_mem_range_guarded(&cmem, base_addr, end);
if (ret) {
pr_err("Failed to remove hot-unplugged memory from crash memory ranges\n");
goto out;
diff --git a/arch/powerpc/kexec/ranges.c b/arch/powerpc/kexec/ranges.c
index 867135560e5c..6c58bcc3e130 100644
--- a/arch/powerpc/kexec/ranges.c
+++ b/arch/powerpc/kexec/ranges.c
@@ -553,7 +553,7 @@ int get_usable_memory_ranges(struct crash_mem **mem_ranges)
#endif /* CONFIG_KEXEC_FILE */
#ifdef CONFIG_CRASH_DUMP
-static int crash_exclude_mem_range_guarded(struct crash_mem **mem_ranges,
+int crash_exclude_mem_range_guarded(struct crash_mem **mem_ranges,
unsigned long long mstart,
unsigned long long mend)
{
@@ -641,89 +641,4 @@ int get_crash_memory_ranges(struct crash_mem **mem_ranges)
pr_err("Failed to setup crash memory ranges\n");
return ret;
}
-
-/**
- * remove_mem_range - Removes the given memory range from the range list.
- * @mem_ranges: Range list to remove the memory range to.
- * @base: Base address of the range to remove.
- * @size: Size of the memory range to remove.
- *
- * (Re)allocates memory, if needed.
- *
- * Returns 0 on success, negative errno on error.
- */
-int remove_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size)
-{
- u64 end;
- int ret = 0;
- unsigned int i;
- u64 mstart, mend;
- struct crash_mem *mem_rngs = *mem_ranges;
-
- if (!size)
- return 0;
-
- /*
- * Memory range are stored as start and end address, use
- * the same format to do remove operation.
- */
- end = base + size - 1;
-
- for (i = 0; i < mem_rngs->nr_ranges; i++) {
- mstart = mem_rngs->ranges[i].start;
- mend = mem_rngs->ranges[i].end;
-
- /*
- * Memory range to remove is not part of this range entry
- * in the memory range list
- */
- if (!(base >= mstart && end <= mend))
- continue;
-
- /*
- * Memory range to remove is equivalent to this entry in the
- * memory range list. Remove the range entry from the list.
- */
- if (base == mstart && end == mend) {
- for (; i < mem_rngs->nr_ranges - 1; i++) {
- mem_rngs->ranges[i].start = mem_rngs->ranges[i+1].start;
- mem_rngs->ranges[i].end = mem_rngs->ranges[i+1].end;
- }
- mem_rngs->nr_ranges--;
- goto out;
- }
- /*
- * Start address of the memory range to remove and the
- * current memory range entry in the list is same. Just
- * move the start address of the current memory range
- * entry in the list to end + 1.
- */
- else if (base == mstart) {
- mem_rngs->ranges[i].start = end + 1;
- goto out;
- }
- /*
- * End address of the memory range to remove and the
- * current memory range entry in the list is same.
- * Just move the end address of the current memory
- * range entry in the list to base - 1.
- */
- else if (end == mend) {
- mem_rngs->ranges[i].end = base - 1;
- goto out;
- }
- /*
- * Memory range to remove is not at the edge of current
- * memory range entry. Split the current memory entry into
- * two half.
- */
- else {
- size = mem_rngs->ranges[i].end - end + 1;
- mem_rngs->ranges[i].end = base - 1;
- ret = add_mem_range(mem_ranges, end + 1, size);
- }
- }
-out:
- return ret;
-}
#endif /* CONFIG_CRASH_DUMP */
--
2.34.1
^ permalink raw reply related
* [PATCH v13 10/15] x86/kexec: Use crash_prepare_headers() helper to simplify code
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
Use the newly introduced crash_prepare_headers() function to replace
the existing prepare_elf_headers(), allocate cmem and exclude crash kernel
memory in the crash core, which reduce code duplication.
Only the following three architecture functions need to be implemented:
- arch_get_system_nr_ranges(). Call get_nr_ram_ranges_callback()
to pre-count the max number of memory ranges.
- arch_crash_populate_cmem(). Use prepare_elf64_ram_headers_callback()
to collect the memory ranges and fills them into cmem.
- arch_crash_exclude_ranges(). Exclude the low 1M for x86.
By the way, remove the unused "nr_mem_ranges" in
arch_crash_handle_hotplug_event().
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/x86/kernel/crash.c | 89 +++++------------------------------------
1 file changed, 11 insertions(+), 78 deletions(-)
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index fa6a1feb1bf1..8cf6e115196e 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -153,16 +153,8 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
return 0;
}
-/* Gather all the required information to prepare elf headers for ram regions */
-static struct crash_mem *fill_up_crash_elf_data(void)
+unsigned int arch_get_system_nr_ranges(void)
{
- unsigned int nr_ranges = 0;
- struct crash_mem *cmem;
-
- walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
- if (!nr_ranges)
- return NULL;
-
/*
* Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
* may cause range splits. So add extra slots here.
@@ -177,49 +169,16 @@ static struct crash_mem *fill_up_crash_elf_data(void)
* But in order to lest the low 1M could be changed in the future,
* (e.g. [start, 1M]), add a extra slot.
*/
- nr_ranges += 3 + crashk_cma_cnt;
- cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
- if (!cmem)
- return NULL;
-
- cmem->max_nr_ranges = nr_ranges;
+ unsigned int nr_ranges = 3 + crashk_cma_cnt;
- return cmem;
+ walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
+ return nr_ranges;
}
-/*
- * Look for any unwanted ranges between mstart, mend and remove them. This
- * might lead to split and split ranges are put in cmem->ranges[] array
- */
-static int elf_header_exclude_ranges(struct crash_mem *cmem)
+int arch_crash_exclude_ranges(struct crash_mem *cmem)
{
- int ret = 0;
- int i;
-
/* Exclude the low 1M because it is always reserved */
- ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
- if (ret)
- return ret;
-
- /* Exclude crashkernel region */
- ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
- if (ret)
- return ret;
-
- if (crashk_low_res.end)
- ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
- crashk_low_res.end);
- if (ret)
- return ret;
-
- for (i = 0; i < crashk_cma_cnt; ++i) {
- ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
- crashk_cma_ranges[i].end);
- if (ret)
- return ret;
- }
-
- return 0;
+ return crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
}
static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
@@ -236,35 +195,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
return 0;
}
-/* Prepare elf headers. Return addr and size */
-static int prepare_elf_headers(void **addr, unsigned long *sz,
- unsigned long *nr_mem_ranges)
+int arch_crash_populate_cmem(struct crash_mem *cmem)
{
- struct crash_mem *cmem;
- int ret;
-
- cmem = fill_up_crash_elf_data();
- if (!cmem)
- return -ENOMEM;
-
- ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
- if (ret)
- goto out;
-
- /* Exclude unwanted mem ranges */
- ret = elf_header_exclude_ranges(cmem);
- if (ret)
- goto out;
-
- /* Return the computed number of memory ranges, for hotplug usage */
- *nr_mem_ranges = cmem->nr_ranges;
-
- /* By default prepare 64bit headers */
- ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
-
-out:
- vfree(cmem);
- return ret;
+ return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
}
#endif
@@ -422,7 +355,8 @@ int crash_load_segments(struct kimage *image)
.buf_max = ULONG_MAX, .top_down = false };
/* Prepare elf headers and add a segment */
- ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
+ ret = crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &kbuf.buffer,
+ &kbuf.bufsz, &pnum);
if (ret)
return ret;
@@ -515,7 +449,6 @@ unsigned int arch_crash_get_elfcorehdr_size(void)
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
{
void *elfbuf = NULL, *old_elfcorehdr;
- unsigned long nr_mem_ranges;
unsigned long mem, memsz;
unsigned long elfsz = 0;
@@ -533,7 +466,7 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
* Create the new elfcorehdr reflecting the changes to CPU and/or
* memory resources.
*/
- if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
+ if (crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz, NULL)) {
pr_err("unable to create new elfcorehdr");
goto out;
}
--
2.34.1
^ permalink raw reply related
* [PATCH v13 06/15] LoongArch: kexec: Fix potential buffer overflow in prepare_elf_headers()
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
There is a race condition between the kexec_load() system call
(crash kernel loading path) and memory hotplug operations that can lead
to buffer overflow and potential kernel crash.
During prepare_elf_headers(), the following steps occur:
1. The first for_each_mem_range() queries current System RAM memory ranges
2. Allocates buffer based on queried count
3. The 2st for_each_mem_range() populates ranges from memblock
If memory hotplug occurs between step 1 and step 3, the number of ranges
can increase, causing out-of-bounds write when populating cmem->ranges[].
This happens because kexec_load() uses kexec_trylock (atomic_t) while
memory hotplug uses device_hotplug_lock (mutex), so they don't serialize
with each other.
Just add bounds checking to prevent out-of-bounds access.
Cc: Youling Tang <tangyouling@kylinos.cn>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: stable@vger.kernel.org
Fixes: 1bcca8620a91 ("LoongArch: Add crash dump support for kexec_file")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/loongarch/kernel/machine_kexec_file.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
index 5584b798ba46..167392c1da33 100644
--- a/arch/loongarch/kernel/machine_kexec_file.c
+++ b/arch/loongarch/kernel/machine_kexec_file.c
@@ -75,6 +75,11 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
cmem->max_nr_ranges = nr_ranges;
cmem->nr_ranges = 0;
for_each_mem_range(i, &start, &end) {
+ if (cmem->nr_ranges >= cmem->max_nr_ranges) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
cmem->ranges[cmem->nr_ranges].start = start;
cmem->ranges[cmem->nr_ranges].end = end - 1;
cmem->nr_ranges++;
--
2.34.1
^ permalink raw reply related
* [PATCH v13 08/15] crash: Add crash_prepare_headers() to exclude crash kernel memory
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
The crash memory alloc, and the exclude of crashk_res, crashk_low_res
and crashk_cma memory are almost identical across different architectures,
handling them in the crash core would eliminate a lot of duplication, so
add crash_prepare_headers() helper to handle them in the common code.
To achieve the above goal, three architecture-specific functions are
introduced:
- arch_get_system_nr_ranges(). Pre-counts the max number of memory ranges.
- arch_crash_populate_cmem(). Collects the memory ranges and fills them
into cmem.
- arch_crash_exclude_ranges(). Architecture's additional crash memory
ranges exclusion, defaulting to empty.
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
include/linux/crash_core.h | 5 +++
kernel/crash_core.c | 91 ++++++++++++++++++++++++++++++++++++--
2 files changed, 93 insertions(+), 3 deletions(-)
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index c1dee3f971a9..583ffcc703d4 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -59,6 +59,8 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
unsigned long long mend);
extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
void **addr, unsigned long *sz);
+extern int crash_prepare_headers(int need_kernel_map, void **addr,
+ unsigned long *sz, unsigned long *nr_mem_ranges);
struct kimage;
struct kexec_segment;
@@ -76,6 +78,9 @@ int kexec_should_crash(struct task_struct *p);
int kexec_crash_loaded(void);
void crash_save_cpu(struct pt_regs *regs, int cpu);
extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
+extern unsigned int arch_get_system_nr_ranges(void);
+extern int arch_crash_populate_cmem(struct crash_mem *cmem);
+extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
#else /* !CONFIG_CRASH_DUMP*/
struct pt_regs;
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 4f21fc3b108b..d28be3890efb 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -16,6 +16,7 @@
#include <linux/mm.h>
#include <linux/cpuhotplug.h>
#include <linux/memblock.h>
+#include <linux/memory_hotplug.h>
#include <linux/kmemleak.h>
#include <linux/crash_core.h>
#include <linux/reboot.h>
@@ -168,9 +169,6 @@ static inline resource_size_t crash_resource_size(const struct resource *res)
return !res->end ? 0 : resource_size(res);
}
-
-
-
int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
void **addr, unsigned long *sz)
{
@@ -272,6 +270,93 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
return 0;
}
+static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
+{
+ struct crash_mem *cmem;
+
+ cmem = kvzalloc_flex(*cmem, ranges, nr_ranges);
+ if (!cmem)
+ return NULL;
+
+ cmem->max_nr_ranges = nr_ranges;
+ return cmem;
+}
+
+unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
+int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
+int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
+
+static int crash_exclude_core_ranges(struct crash_mem *cmem)
+{
+ int ret, i;
+
+ /* Exclude crashkernel region */
+ ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
+ if (ret)
+ return ret;
+
+ if (crashk_low_res.end) {
+ ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
+ if (ret)
+ return ret;
+ }
+
+ for (i = 0; i < crashk_cma_cnt; ++i) {
+ ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
+ crashk_cma_ranges[i].end);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
+ unsigned long *nr_mem_ranges)
+{
+ unsigned int max_nr_ranges;
+ struct crash_mem *cmem;
+ int ret;
+
+ get_online_mems();
+ max_nr_ranges = arch_get_system_nr_ranges();
+ if (!max_nr_ranges) {
+ put_online_mems();
+ return -ENOMEM;
+ }
+
+ cmem = alloc_cmem(max_nr_ranges);
+ if (!cmem) {
+ put_online_mems();
+ return -ENOMEM;
+ }
+
+ ret = arch_crash_populate_cmem(cmem);
+ if (ret) {
+ put_online_mems();
+ goto out;
+ }
+
+ put_online_mems();
+ ret = crash_exclude_core_ranges(cmem);
+ if (ret)
+ goto out;
+
+ ret = arch_crash_exclude_ranges(cmem);
+ if (ret)
+ goto out;
+
+ /* Return the computed number of memory ranges, for hotplug usage */
+ if (nr_mem_ranges)
+ *nr_mem_ranges = cmem->nr_ranges;
+
+ ret = crash_prepare_elf64_headers(cmem, need_kernel_map, addr, sz);
+
+out:
+ kvfree(cmem);
+ return ret;
+}
+
/**
* crash_exclude_mem_range - exclude a mem range for existing ranges
* @mem: mem->range contains an array of ranges sorted in ascending order
--
2.34.1
^ permalink raw reply related
* [PATCH v13 05/15] riscv: kexec_file: Fix potential buffer overflow in prepare_elf_headers()
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
There is a race condition between the kexec_load() system call
(crash kernel loading path) and memory hotplug operations that can lead
to buffer overflow and potential kernel crash.
During prepare_elf_headers(), the following steps occur:
1. get_nr_ram_ranges_callback() queries current System RAM memory ranges
2. Allocates buffer based on queried count
3. prepare_elf64_ram_headers_callback() populates ranges from memblock
If memory hotplug occurs between step 1 and step 3, the number of ranges
can increase, causing out-of-bounds write when populating cmem->ranges[].
This happens because kexec_load() uses kexec_trylock (atomic_t) while
memory hotplug uses device_hotplug_lock (mutex), so they don't serialize
with each other.
While this works today because RISC-V server hardware with hotplug
support is still rare and most deployments use fixed memory configurations
(e.g., QEMU virt machine), it is technically fragile. So add bounds
checking in prepare_elf64_ram_headers_callback() to prevent
out-of-bounds (OOB) access.
No functional change for current RISC-V deployments, but makes
the code robust against future hotplug-capable platforms.
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: songshuaishuai@tinylab.org
Cc: bjorn@rivosinc.com
Cc: leitao@debian.org
Fixes: 8acea455fafa ("RISC-V: Support for kexec_file on panic")
Reviewed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/riscv/kernel/machine_kexec_file.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index 3f7766057cac..773a1cba8ba0 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -48,6 +48,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
{
struct crash_mem *cmem = arg;
+ if (cmem->nr_ranges >= cmem->max_nr_ranges)
+ return -ENOMEM;
+
cmem->ranges[cmem->nr_ranges].start = res->start;
cmem->ranges[cmem->nr_ranges].end = res->end;
cmem->nr_ranges++;
--
2.34.1
^ permalink raw reply related
* [PATCH v13 04/15] arm64: kexec_file: Fix potential buffer overflow in prepare_elf_headers()
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
There is a race condition between the kexec_load() system call
(crash kernel loading path) and memory hotplug operations that can
lead to buffer overflow and potential kernel crash.
During prepare_elf_headers(), the following steps occur:
1. The first for_each_mem_range() queries current System RAM memory ranges
2. Allocates buffer based on queried count
3. The 2st for_each_mem_range() populates ranges from memblock
If memory hotplug occurs between step 1 and step 3, the number of ranges
can increase, causing out-of-bounds write when populating cmem->ranges[].
This happens because kexec_load() uses kexec_trylock (atomic_t) while
memory hotplug uses device_hotplug_lock (mutex), so they don't serialize
with each other.
Add the explicit bounds checking to prevent out-of-bounds access.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: stable@vger.kernel.org
Fixes: 3751e728cef2 ("arm64: kexec_file: add crash dump support")
Closes: https://sashiko.dev/#/patchset/20260323072745.2481719-1-ruanjinjie%40huawei.com
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/arm64/kernel/machine_kexec_file.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index e31fabed378a..a67e7b1abbab 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -59,6 +59,11 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
cmem->max_nr_ranges = nr_ranges;
cmem->nr_ranges = 0;
for_each_mem_range(i, &start, &end) {
+ if (cmem->nr_ranges >= cmem->max_nr_ranges) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
cmem->ranges[cmem->nr_ranges].start = start;
cmem->ranges[cmem->nr_ranges].end = end - 1;
cmem->nr_ranges++;
--
2.34.1
^ permalink raw reply related
* [PATCH v13 03/15] x86/kexec: Fix potential buffer overflow in prepare_elf_headers()
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
There is a race condition between the kexec_load() system call
(crash kernel loading path) and memory hotplug operations that can lead
to buffer overflow and potential kernel crash.
During prepare_elf_headers(), the following steps occur:
1. get_nr_ram_ranges_callback() queries current System RAM memory ranges
2. Allocates buffer based on queried count
3. prepare_elf64_ram_headers_callback() populates ranges from memblock
If memory hotplug occurs between step 1 and step 3, the number of ranges
can increase, causing out-of-bounds write when populating cmem->ranges[].
This happens because kexec_load() uses kexec_trylock (atomic_t) while
memory hotplug uses device_hotplug_lock (mutex), so they don't serialize
with each other.
Since x86 supports crash hotplug, any data inconsistency caused by
a race during the initial load will be corrected by the subsequent
hotplug update. However, we must prevent a buffer overflow if the
number of memory regions increases between the two passes.
Add a boundary checking in prepare_elf64_ram_headers_callback() to ensure
that the number of populated ranges does not exceed
the allocated maximum.
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 8d5f894a3108 ("x86: kexec_file: lift CRASH_MAX_RANGES limit on crash_mem buffer")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/x86/kernel/crash.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index cd796818d94d..fa6a1feb1bf1 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -226,6 +226,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
{
struct crash_mem *cmem = arg;
+ if (cmem->nr_ranges >= cmem->max_nr_ranges)
+ return -ENOMEM;
+
cmem->ranges[cmem->nr_ranges].start = res->start;
cmem->ranges[cmem->nr_ranges].end = res->end;
cmem->nr_ranges++;
--
2.34.1
^ permalink raw reply related
* [PATCH v13 02/15] powerpc/crash: Fix possible memory leak in update_crash_elfcorehdr()
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
In get_crash_memory_ranges(), if crash_exclude_mem_range() failed
after realloc_mem_ranges() has successfully allocated the cmem
memory, it just returns an error but leaves cmem pointing to
the allocated memory, nor is it freed in the caller
update_crash_elfcorehdr(), which cause a memory leak, goto out
to free the cmem.
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Fixes: 849599b702ef ("powerpc/crash: add crash memory hotplug support")
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/powerpc/kexec/crash.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c
index e6539f213b3d..a520f851c3a6 100644
--- a/arch/powerpc/kexec/crash.c
+++ b/arch/powerpc/kexec/crash.c
@@ -502,7 +502,7 @@ static void update_crash_elfcorehdr(struct kimage *image, struct memory_notify *
ret = get_crash_memory_ranges(&cmem);
if (ret) {
pr_err("Failed to get crash mem range\n");
- return;
+ goto out;
}
/*
--
2.34.1
^ permalink raw reply related
* [PATCH v13 01/15] riscv: kexec_file: Fix crashk_low_res not exclude bug
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
In-Reply-To: <20260511030454.1730881-1-ruanjinjie@huawei.com>
As done in commit 944a45abfabc ("arm64: kdump: Reimplement crashkernel=X")
and commit 4831be702b95 ("arm64/kexec: Fix missing extra range for
crashkres_low.") for arm64, while implementing crashkernel=X,[high,low],
riscv should have excluded the "crashk_low_res" reserved ranges from
the crash kernel memory to prevent them from being exported through
/proc/vmcore, and the exclusion would need an extra crash_mem range.
Just simply tested on qemu with crashkernel=4G with kexec in [1] mentioned
in [2]. And the second kernel can be started normally.
# dmesg | grep crash
[ 0.000000] crashkernel low memory reserved: 0xf8000000 - 0x100000000 (128 MB)
[ 0.000000] crashkernel reserved: 0x000000017fe00000 - 0x000000027fe00000 (4096 MB)
Cc: Guo Ren <guoren@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
[1]: https://github.com/chenjh005/kexec-tools/tree/build-test-riscv-v2
[2]: https://lore.kernel.org/all/20230726175000.2536220-1-chenjiahao16@huawei.com/
Fixes: 5882e5acf18d ("riscv: kdump: Implement crashkernel=X,[high,low]")
Reviewed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/riscv/kernel/machine_kexec_file.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index 54e2d9552e93..3f7766057cac 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -61,7 +61,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
unsigned int nr_ranges;
int ret;
- nr_ranges = 1; /* For exclusion of crashkernel region */
+ nr_ranges = 2; /* For exclusion of crashkernel region */
walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
@@ -76,8 +76,16 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
/* Exclude crashkernel region */
ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
- if (!ret)
- ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
+ if (ret)
+ goto out;
+
+ if (crashk_low_res.end) {
+ ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
+ if (ret)
+ goto out;
+ }
+
+ ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
out:
kfree(cmem);
--
2.34.1
^ permalink raw reply related
* [PATCH v13 00/15] arm64/riscv: Add support for crashkernel CMA reservation
From: Jinjie Ruan @ 2026-05-11 3:04 UTC (permalink / raw)
To: corbet, skhan, catalin.marinas, will, chenhuacai, kernel, maddy,
mpe, npiggin, chleroy, pjw, palmer, aou, alex, tglx, mingo, bp,
dave.hansen, hpa, robh, saravanak, akpm, bhe, rppt,
pasha.tatashin, pratyush, ruirui.yang, rdunlap, pmladek,
dapeng1.mi, kees, elver, kuba, ebiggers, lirongqing, paulmck,
ruanjinjie, sourabhjain, coxu, leitao, jbohac, ryan.roberts,
osandov, cfsworks, tangyouling, ritesh.list, adityag, guoren,
songshuaishuai, kevin.brodsky, vishal.moola, junhui.liu,
wangruikang, namcao, chao.gao, seanjc, fuqiang.wang, ardb,
chenjiahao16, hbathini, takahiro.akashi, james.morse, lizhengyu3,
x86, linux-doc, linux-kernel, linux-arm-kernel, loongarch,
linuxppc-dev, linux-riscv, devicetree, kexec
The crash memory allocation, and the exclude of crashk_res, crashk_low_res
and crashk_cma memory are almost identical across different architectures,
This patch set handle them in crash core in a general way, which eliminate
a lot of duplication code.
And add support for crashkernel CMA reservation for arm64 and riscv.
Rebased on v7.1-rc1.
Basic second kernel boot test were performed on QEMU platforms for x86,
ARM64 and RISC-V architectures with the following parameters:
"cma=256M crashkernel=4G crashkernel=64M,cma"
For first kernel, there will be such log:
# dmesg | grep crash
[ 0.000000] crashkernel low memory reserved: 0xe8000000 - 0xf0000000 (128 MB)
[ 0.000000] crashkernel reserved: 0x000000023e600000 - 0x000000033e600000 (4096 MB)
[ 0.000000] crashkernel CMA reserved: 64 MB in 1 ranges
# dmesg | grep cma
[ 0.000000] cma: Reserved 256 MiB at 0x00000000f0000000
[ 0.000000] cma: Reserved 64 MiB at 0x0000000100000000
For second kernel, there will be such log:
[ 0.000000] OF: fdt: Looking for usable-memory-range property...
[ 0.000000] OF: fdt: cap_mem_regions[0]: base=0x000000023e600000, size=0x0000000100000000
[ 0.000000] OF: fdt: cap_mem_regions[1]: base=0x00000000e8000000, size=0x0000000008000000
[ 0.000000] OF: fdt: cap_mem_regions[2]: base=0x0000000100000000, size=0x0000000004000000
Changes in v13:
- Rebased on v7.1-rc1.
- Update the commit message.
- Add Reviewed-by.
- Link to v12: https://lore.kernel.org/all/20260402072701.628293-1-ruanjinjie@huawei.com/
Changes in v12:
- Remove the unused "nr_mem_ranges" for x86.
- Add "Fix crashk_low_res not exclude bug" test log.
- Provide a separate patch for each architecture for using
crash_prepare_headers(), which will make the review more convenient.
- Add Reviewed-by and Tested-by.
- Link to v11: https://lore.kernel.org/all/20260328074013.3589544-1-ruanjinjie@huawei.com/
Changes in v11:
- Avoid silently drop crash memory if the crash kernel is built without
CONFIG_CMA.
- Remove unnecessary "cmem->nr_ranges = 0" for arch_crash_populate_cmem()
as we use kvzalloc().
- Provide a separate patch for each architecture to fix the existing
buffer overflow issue.
- Add Acked-bys for arm64.
Changes in v10:
- Fix crashk_low_res not excluded bug in the existing
RISC-V code.
- Fix an existing memory leak issue in the existing PowerPC code.
- Fix the ordering issue of adding CMA ranges to
"linux,usable-memory-range".
- Fix an existing concurrency issue. A Concurrent memory hotplug may occur
between reading memblock and attempting to fill cmem during kexec_load()
for almost all existing architectures.
- Link to v9: https://lore.kernel.org/all/20260323072745.2481719-1-ruanjinjie@huawei.com/
Changes in v9:
- Collect Reviewed-by and Acked-by, and prepare for Sashiko AI review.
- Link to v8: https://lore.kernel.org/all/20260302035315.3892241-1-ruanjinjie@huawei.com/
Changes in v8:
- Fix the build issues reported by kernel test robot and Sourabh.
- Link to v7: https://lore.kernel.org/all/20260226130437.1867658-1-ruanjinjie@huawei.com/
Changes in v7:
- Correct the inclusion of CMA-reserved ranges for kdump kernel in of/kexec
for arm64 and riscv.
- Add Acked-by.
- Link to v6: https://lore.kernel.org/all/20260224085342.387996-1-ruanjinjie@huawei.com/
Changes in v6:
- Update the crash core exclude code as Mike suggested.
- Rebased on v7.0-rc1.
- Add acked-by.
- Link to v5: https://lore.kernel.org/all/20260212101001.343158-1-ruanjinjie@huawei.com/
Jinjie Ruan (14):
riscv: kexec_file: Fix crashk_low_res not exclude bug
powerpc/crash: Fix possible memory leak in update_crash_elfcorehdr()
x86/kexec: Fix potential buffer overflow in prepare_elf_headers()
arm64: kexec_file: Fix potential buffer overflow in
prepare_elf_headers()
riscv: kexec_file: Fix potential buffer overflow in
prepare_elf_headers()
LoongArch: kexec: Fix potential buffer overflow in
prepare_elf_headers()
crash: Add crash_prepare_headers() to exclude crash kernel memory
arm64: kexec_file: Use crash_prepare_headers() helper to simplify code
x86/kexec: Use crash_prepare_headers() helper to simplify code
riscv: kexec_file: Use crash_prepare_headers() helper to simplify code
LoongArch: kexec: Use crash_prepare_headers() helper to simplify code
crash: Use crash_exclude_core_ranges() on powerpc
arm64: kexec: Add support for crashkernel CMA reservation
riscv: kexec: Add support for crashkernel CMA reservation
Sourabh Jain (1):
powerpc/crash: sort crash memory ranges before preparing elfcorehdr
.../admin-guide/kernel-parameters.txt | 16 +--
arch/arm64/kernel/machine_kexec_file.c | 43 +++-----
arch/arm64/mm/init.c | 5 +-
arch/loongarch/kernel/machine_kexec_file.c | 43 +++-----
arch/powerpc/include/asm/kexec_ranges.h | 1 -
arch/powerpc/kexec/crash.c | 7 +-
arch/powerpc/kexec/ranges.c | 101 +-----------------
arch/riscv/kernel/machine_kexec_file.c | 42 +++-----
arch/riscv/mm/init.c | 5 +-
arch/x86/kernel/crash.c | 92 +++-------------
drivers/of/fdt.c | 9 +-
drivers/of/kexec.c | 9 ++
include/linux/crash_core.h | 9 ++
include/linux/crash_reserve.h | 4 +-
kernel/crash_core.c | 98 ++++++++++++++++-
15 files changed, 202 insertions(+), 282 deletions(-)
--
2.34.1
^ permalink raw reply
* Re: [PATCH] ASoC: docs: Fix stale and misspelled references
From: Mark Brown @ 2026-05-10 13:46 UTC (permalink / raw)
To: Takashi Iwai, Jonathan Corbet, Shuah Khan, Liam Girdwood,
Jaroslav Kysela, Cássio Gabriel
Cc: linux-sound, linux-doc, linux-kernel
In-Reply-To: <20260508-asoc-doc-fixes-v1-1-b53eec42e340@gmail.com>
On Fri, 08 May 2026 01:20:50 -0300, Cássio Gabriel wrote:
> ASoC: docs: Fix stale and misspelled references
Applied to
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-7.2
Thanks!
[1/1] ASoC: docs: Fix stale and misspelled references
https://git.kernel.org/broonie/sound/c/b2d1eaa9b660
All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.
You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.
If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.
Please add any relevant lists and maintainers to the CCs when replying
to this mail.
Thanks,
Mark
^ permalink raw reply
* Re: [RFC v2 0/2] add kconfirm
From: Jan Engelhardt @ 2026-05-10 23:28 UTC (permalink / raw)
To: Miguel Ojeda
Cc: Julian Braha, nathan, nsc, jani.nikula, akpm, gary, ljs, arnd,
gregkh, masahiroy, ojeda, corbet, qingfang.deng, linux-kernel,
rust-for-linux, linux-doc, linux-kbuild
In-Reply-To: <CANiq72kUD=s7VkOUBNFLbcASvDoO_qFXHziOcSFdDqtg5NXoUw@mail.gmail.com>
On Sunday 2026-05-10 11:49, Miguel Ojeda wrote:
>On Sun, May 10, 2026 at 7:06 AM Jan Engelhardt <ej@inai.de> wrote:
>>
>> Good lord, how is anyone supposed to review that amount –
>> or is it just getting rubberstamped anyway?
>
>[...] another option for that may be using the distribution's
>registry
That should really be the target. After all, Linux is not bundling
e.g. ncurses (for `make menuconfig`, if one wants to use it)
or libelf (mandatory for objtool and thus everything) either.
>the versions need to fit, one still needs to provide a way
>to do it for distributions that do not match, etc.
Linux, and many other projects, have run on a "The system version is
king" model for a long time. If libelf, binutils, gcc, libx11, or
whatever the dependency in question may be, the project trying to use
a dependency would add a few-liner patch to broaden the accepted
range, rather than trying to re-provide the dependency as a whole.
^ permalink raw reply
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