From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH v4 09/17] powerpc/64: allow alternate return locations for soft-masked interrupts
Date: Fri, 18 Jun 2021 01:51:08 +1000 [thread overview]
Message-ID: <20210617155116.2167984-10-npiggin@gmail.com> (raw)
In-Reply-To: <20210617155116.2167984-1-npiggin@gmail.com>
The exception table fixup adjusts a failed page fault's interrupt return
location if it was taken at an address specified in the exception table,
to a corresponding fixup handler address.
Introduce a variation of that idea which adds a fixup table for NMIs and
soft-masked asynchronous interrupts. This will be used to protect
certain critical sections that are sensitive to being clobbered by
interrupts coming in (due to using the same SPRs and/or irq soft-mask
state).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/interrupt.h | 13 +++++++++
arch/powerpc/include/asm/ppc_asm.h | 8 ++++++
arch/powerpc/kernel/exceptions-64e.S | 37 +++++++++++++++++++++++--
arch/powerpc/kernel/exceptions-64s.S | 41 ++++++++++++++++++++++++++++
arch/powerpc/kernel/vmlinux.lds.S | 10 +++++++
arch/powerpc/lib/Makefile | 2 +-
arch/powerpc/lib/restart_table.c | 30 ++++++++++++++++++++
7 files changed, 138 insertions(+), 3 deletions(-)
create mode 100644 arch/powerpc/lib/restart_table.c
diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index b9c510187b58..49d9a6fd1bb9 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -73,6 +73,11 @@
#include <asm/kprobes.h>
#include <asm/runlatch.h>
+#ifdef CONFIG_PPC64
+extern char __end_soft_masked[];
+unsigned long search_kernel_restart_table(unsigned long addr);
+#endif
+
#ifdef CONFIG_PPC_BOOK3S_64
static inline void srr_regs_clobbered(void)
{
@@ -287,6 +292,14 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter
* new work to do (must use irq_work for that).
*/
+#ifdef CONFIG_PPC64
+ if (arch_irq_disabled_regs(regs)) {
+ unsigned long rst = search_kernel_restart_table(regs->nip);
+ if (rst)
+ regs_set_return_ip(regs, rst);
+ }
+#endif
+
#ifdef CONFIG_PPC64
if (nmi_disables_ftrace(regs))
this_cpu_set_ftrace_enabled(state->ftrace_enabled);
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index d6739d700f0a..c9c2c36c1f8f 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -762,6 +762,14 @@ END_FTR_SECTION_NESTED(CPU_FTR_CELL_TB_BUG, CPU_FTR_CELL_TB_BUG, 96)
stringify_in_c(.long (_target) - . ;) \
stringify_in_c(.previous)
+#define RESTART_TABLE(_start, _end, _target) \
+ stringify_in_c(.section __restart_table,"a";)\
+ stringify_in_c(.balign 8;) \
+ stringify_in_c(.llong (_start);) \
+ stringify_in_c(.llong (_end);) \
+ stringify_in_c(.llong (_target);) \
+ stringify_in_c(.previous)
+
#ifdef CONFIG_PPC_FSL_BOOK3E
#define BTB_FLUSH(reg) \
lis reg,BUCSR_INIT@h; \
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index b35c97c7082f..1b79f8a75298 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -901,6 +901,28 @@ kernel_dbg_exc:
bl unknown_exception
b interrupt_return
+.macro SEARCH_RESTART_TABLE
+ LOAD_REG_IMMEDIATE_SYM(r14, r11, __start___restart_table)
+ LOAD_REG_IMMEDIATE_SYM(r15, r11, __stop___restart_table)
+300:
+ cmpd r14,r15
+ beq 302f
+ ld r11,0(r14)
+ cmpld r10,r11
+ blt 301f
+ ld r11,8(r14)
+ cmpld r10,r11
+ bge 301f
+ ld r11,16(r14)
+ b 303f
+301:
+ addi r14,r14,24
+ b 300b
+302:
+ li r11,0
+303:
+.endm
+
/*
* An interrupt came in while soft-disabled; We mark paca->irq_happened
* accordingly and if the interrupt is level sensitive, we hard disable
@@ -909,6 +931,9 @@ kernel_dbg_exc:
*/
.macro masked_interrupt_book3e paca_irq full_mask
+ std r14,PACA_EXGEN+EX_R14(r13)
+ std r15,PACA_EXGEN+EX_R15(r13)
+
lbz r10,PACAIRQHAPPENED(r13)
.if \full_mask == 1
ori r10,r10,\paca_irq | PACA_IRQ_HARD_DIS
@@ -918,15 +943,23 @@ kernel_dbg_exc:
stb r10,PACAIRQHAPPENED(r13)
.if \full_mask == 1
- rldicl r10,r11,48,1 /* clear MSR_EE */
- rotldi r11,r10,16
+ xori r11,r11,MSR_EE /* clear MSR_EE */
mtspr SPRN_SRR1,r11
.endif
+ mfspr r10,SPRN_SRR0
+ SEARCH_RESTART_TABLE
+ cmpdi r11,0
+ beq 1f
+ mtspr SPRN_SRR0,r11 /* return to restart address */
+1:
+
lwz r11,PACA_EXGEN+EX_CR(r13)
mtcr r11
ld r10,PACA_EXGEN+EX_R10(r13)
ld r11,PACA_EXGEN+EX_R11(r13)
+ ld r14,PACA_EXGEN+EX_R14(r13)
+ ld r15,PACA_EXGEN+EX_R15(r13)
mfspr r13,SPRN_SPRG_GEN_SCRATCH
rfi
b .
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 0ba8c2387aac..17a213f25c92 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -664,6 +664,36 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
__GEN_COMMON_BODY \name
.endm
+.macro SEARCH_RESTART_TABLE
+#ifdef CONFIG_RELOCATABLE
+ mr r12,r2
+ ld r2,PACATOC(r13)
+ LOAD_REG_ADDR(r9, __start___restart_table)
+ LOAD_REG_ADDR(r10, __stop___restart_table)
+ mr r2,r12
+#else
+ LOAD_REG_IMMEDIATE_SYM(r9, r12, __start___restart_table)
+ LOAD_REG_IMMEDIATE_SYM(r10, r12, __stop___restart_table)
+#endif
+300:
+ cmpd r9,r10
+ beq 302f
+ ld r12,0(r9)
+ cmpld r11,r12
+ blt 301f
+ ld r12,8(r9)
+ cmpld r11,r12
+ bge 301f
+ ld r12,16(r9)
+ b 303f
+301:
+ addi r9,r9,24
+ b 300b
+302:
+ li r12,0
+303:
+.endm
+
/*
* Restore all registers including H/SRR0/1 saved in a stack frame of a
* standard exception.
@@ -2771,6 +2801,7 @@ EXC_COMMON_BEGIN(soft_nmi_common)
mtmsrd r9,1
kuap_kernel_restore r9, r10
+
EXCEPTION_RESTORE_REGS hsrr=0
RFI_TO_KERNEL
@@ -2828,6 +2859,16 @@ masked_interrupt:
stb r9,PACASRR_VALID(r13)
.endif
+ SEARCH_RESTART_TABLE
+ cmpdi r12,0
+ beq 3f
+ .if \hsrr
+ mtspr SPRN_HSRR0,r12
+ .else
+ mtspr SPRN_SRR0,r12
+ .endif
+3:
+
ld r9,PACA_EXGEN+EX_CTR(r13)
mtctr r9
lwz r9,PACA_EXGEN+EX_CCR(r13)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 72fa3c00229a..16c5e13e00c4 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -9,6 +9,14 @@
#define EMITS_PT_NOTE
#define RO_EXCEPTION_TABLE_ALIGN 0
+#define RESTART_TABLE(align) \
+ . = ALIGN(align); \
+ __restart_table : AT(ADDR(__restart_table) - LOAD_OFFSET) { \
+ __start___restart_table = .; \
+ KEEP(*(__restart_table)) \
+ __stop___restart_table = .; \
+ }
+
#include <asm/page.h>
#include <asm-generic/vmlinux.lds.h>
#include <asm/cache.h>
@@ -124,6 +132,8 @@ SECTIONS
RO_DATA(PAGE_SIZE)
#ifdef CONFIG_PPC64
+ RESTART_TABLE(8)
+
. = ALIGN(8);
__stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) {
__start___stf_entry_barrier_fixup = .;
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index cc1a8a0f311e..4c92c80454f3 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -42,7 +42,7 @@ obj-$(CONFIG_PPC_BOOK3S_64) += copyuser_power7.o copypage_power7.o \
memcpy_power7.o
obj64-y += copypage_64.o copyuser_64.o mem_64.o hweight_64.o \
- memcpy_64.o copy_mc_64.o
+ memcpy_64.o copy_mc_64.o restart_table.o
ifndef CONFIG_PPC_QUEUED_SPINLOCKS
obj64-$(CONFIG_SMP) += locks.o
diff --git a/arch/powerpc/lib/restart_table.c b/arch/powerpc/lib/restart_table.c
new file mode 100644
index 000000000000..7cd20757cc33
--- /dev/null
+++ b/arch/powerpc/lib/restart_table.c
@@ -0,0 +1,30 @@
+#include <asm/interrupt.h>
+#include <asm/kprobes.h>
+
+struct restart_table_entry {
+ unsigned long start;
+ unsigned long end;
+ unsigned long fixup;
+};
+
+extern struct restart_table_entry __start___restart_table[];
+extern struct restart_table_entry __stop___restart_table[];
+
+/* Given an address, look for it in the kernel exception table */
+unsigned long search_kernel_restart_table(unsigned long addr)
+{
+ struct restart_table_entry *rte = __start___restart_table;
+
+ while (rte < __stop___restart_table) {
+ unsigned long start = rte->start;
+ unsigned long end = rte->end;
+ unsigned long fixup = rte->fixup;
+
+ if (addr >= start && addr < end)
+ return fixup;
+
+ rte++;
+ }
+ return 0;
+}
+NOKPROBE_SYMBOL(search_kernel_restart_table);
--
2.23.0
next prev parent reply other threads:[~2021-06-17 15:55 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-17 15:50 [PATCH v4 00/17] powerpc/64: fast interrupt exits Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 01/17] powerpc/interrupt: Fix CONFIG ifdef typo Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 02/17] powerpc: remove interrupt exit helpers unused argument Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 03/17] powerpc/64s: introduce different functions to return from SRR vs HSRR interrupts Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 04/17] powerpc/64s: avoid reloading (H)SRR registers if they are still valid Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 05/17] powerpc/64: handle MSR EE and RI in interrupt entry wrapper Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 06/17] powerpc/64: move interrupt return asm to interrupt_64.S Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 07/17] powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE] Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 08/17] powerpc/64s: save one more register in the masked interrupt handler Nicholas Piggin
2021-06-17 15:51 ` Nicholas Piggin [this message]
2021-06-17 15:51 ` [PATCH v4 10/17] powerpc/64: interrupt soft-enable race fix Nicholas Piggin
2022-05-16 16:36 ` Christophe Leroy
2021-06-17 15:51 ` [PATCH v4 11/17] powerpc/64: treat low kernel text as irqs soft-masked Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 12/17] powerpc/64: use interrupt restart table to speed up return from interrupt Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 13/17] powerpc/interrupt: Rename and lightly change syscall_exit_prepare_main() Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 14/17] powerpc/interrupt: Refactor interrupt_exit_user_prepare() Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 15/17] powerpc/interrupt: Interchange prep_irq_for_{kernel_enabled/user}_exit() Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 16/17] powerpc/interrupt: Refactor prep_irq_for_{user/kernel_enabled}_exit() Nicholas Piggin
2021-06-17 15:51 ` [PATCH v4 17/17] powerpc/interrupt: Remove prep_irq_for_user_exit() Nicholas Piggin
2021-06-25 6:21 ` [PATCH v4 00/17] powerpc/64: fast interrupt exits Michael Ellerman
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