[PATCH AUTOSEL 5.4 1/5] pm: cpupower: bench: Prevent NULL dereference on malloc failure

[PATCH AUTOSEL 5.4 1/5] pm: cpupower: bench: Prevent NULL dereference on malloc failure

[Sasha Levin]

From: Zhongqiu Han <quic_zhonhan@quicinc.com>

[ Upstream commit 208baa3ec9043a664d9acfb8174b332e6b17fb69 ]

If malloc returns NULL due to low memory, 'config' pointer can be NULL.
Add a check to prevent NULL dereference.

Link: https://lore.kernel.org/r/20250219122715.3892223-1-quic_zhonhan@quicinc.com
Signed-off-by: Zhongqiu Han <quic_zhonhan@quicinc.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/power/cpupower/bench/parse.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/power/cpupower/bench/parse.c b/tools/power/cpupower/bench/parse.c
index e63dc11fa3a53..48e25be6e1635 100644
--- a/tools/power/cpupower/bench/parse.c
+++ b/tools/power/cpupower/bench/parse.c
@@ -120,6 +120,10 @@ FILE *prepare_output(const char *dirname)
 struct config *prepare_default_config()
 {
 	struct config *config = malloc(sizeof(struct config));
+	if (!config) {
+		perror("malloc");
+		return NULL;
+	}
 
 	dprintf("loading defaults\n");
 
-- 
2.39.5

[PATCH AUTOSEL 5.4 2/5] x86/cpu: Don't clear X86_FEATURE_LAHF_LM flag in init_amd_k8() on AMD when running in a virtual machine

[Sasha Levin]

From: Max Grobecker <max@grobecker.info>

[ Upstream commit a4248ee16f411ac1ea7dfab228a6659b111e3d65 ]

When running in a virtual machine, we might see the original hardware CPU
vendor string (i.e. "AuthenticAMD"), but a model and family ID set by the
hypervisor. In case we run on AMD hardware and the hypervisor sets a model
ID < 0x14, the LAHF cpu feature is eliminated from the the list of CPU
capabilities present to circumvent a bug with some BIOSes in conjunction with
AMD K8 processors.

Parsing the flags list from /proc/cpuinfo seems to be happening mostly in
bash scripts and prebuilt Docker containers, as it does not need to have
additionals tools present – even though more reliable ways like using "kcpuid",
which calls the CPUID instruction instead of parsing a list, should be preferred.
Scripts, that use /proc/cpuinfo to determine if the current CPU is
"compliant" with defined microarchitecture levels like x86-64-v2 will falsely
claim the CPU is incapable of modern CPU instructions when "lahf_lm" is missing
in that flags list.

This can prevent some docker containers from starting or build scripts to create
unoptimized binaries.

Admittably, this is more a small inconvenience than a severe bug in the kernel
and the shoddy scripts that rely on parsing /proc/cpuinfo
should be fixed instead.

This patch adds an additional check to see if we're running inside a
virtual machine (X86_FEATURE_HYPERVISOR is present), which, to my
understanding, can't be present on a real K8 processor as it was introduced
only with the later/other Athlon64 models.

Example output with the "lahf_lm" flag missing in the flags list
(should be shown between "hypervisor" and "abm"):

    $ cat /proc/cpuinfo
    processor       : 0
    vendor_id       : AuthenticAMD
    cpu family      : 15
    model           : 6
    model name      : Common KVM processor
    stepping        : 1
    microcode       : 0x1000065
    cpu MHz         : 2599.998
    cache size      : 512 KB
    physical id     : 0
    siblings        : 1
    core id         : 0
    cpu cores       : 1
    apicid          : 0
    initial apicid  : 0
    fpu             : yes
    fpu_exception   : yes
    cpuid level     : 13
    wp              : yes
    flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
                      cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx rdtscp
                      lm rep_good nopl cpuid extd_apicid tsc_known_freq pni
                      pclmulqdq ssse3 fma cx16 sse4_1 sse4_2 x2apic movbe popcnt
                      tsc_deadline_timer aes xsave avx f16c hypervisor abm
                      3dnowprefetch vmmcall bmi1 avx2 bmi2 xsaveopt

... while kcpuid shows the feature to be present in the CPU:

    # kcpuid -d | grep lahf
         lahf_lm             - LAHF/SAHF available in 64-bit mode

[ mingo: Updated the comment a bit, incorporated Boris's review feedback. ]

Signed-off-by: Max Grobecker <max@grobecker.info>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kernel/cpu/amd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 533451498c8f8..9bcc099484c89 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -808,7 +808,7 @@ static void init_amd_k8(struct cpuinfo_x86 *c)
 	 * (model = 0x14) and later actually support it.
 	 * (AMD Erratum #110, docId: 25759).
 	 */
-	if (c->x86_model < 0x14 && cpu_has(c, X86_FEATURE_LAHF_LM)) {
+	if (c->x86_model < 0x14 && cpu_has(c, X86_FEATURE_LAHF_LM) && !cpu_has(c, X86_FEATURE_HYPERVISOR)) {
 		clear_cpu_cap(c, X86_FEATURE_LAHF_LM);
 		if (!rdmsrl_amd_safe(0xc001100d, &value)) {
 			value &= ~BIT_64(32);
-- 
2.39.5

[PATCH AUTOSEL 5.4 3/5] perf: arm_pmu: Don't disable counter in armpmu_add()

[Sasha Levin]

From: Mark Rutland <mark.rutland@arm.com>

[ Upstream commit dcca27bc1eccb9abc2552aab950b18a9742fb8e7 ]

Currently armpmu_add() tries to handle a newly-allocated counter having
a stale associated event, but this should not be possible, and if this
were to happen the current mitigation is insufficient and potentially
expensive. It would be better to warn if we encounter the impossible
case.

Calls to pmu::add() and pmu::del() are serialized by the core perf code,
and armpmu_del() clears the relevant slot in pmu_hw_events::events[]
before clearing the bit in pmu_hw_events::used_mask such that the
counter can be reallocated. Thus when armpmu_add() allocates a counter
index from pmu_hw_events::used_mask, it should not be possible to observe
a stale even in pmu_hw_events::events[] unless either
pmu_hw_events::used_mask or pmu_hw_events::events[] have been corrupted.

If this were to happen, we'd end up with two events with the same
event->hw.idx, which would clash with each other during reprogramming,
deletion, etc, and produce bogus results. Add a WARN_ON_ONCE() for this
case so that we can detect if this ever occurs in practice.

That possiblity aside, there's no need to call arm_pmu::disable(event)
for the new event. The PMU reset code initialises the counter in a
disabled state, and armpmu_del() will disable the counter before it can
be reused. Remove the redundant disable.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Tested-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250218-arm-brbe-v19-v20-2-4e9922fc2e8e@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/perf/arm_pmu.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index b377872a8f9d6..558ee5401ea89 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -262,12 +262,10 @@ armpmu_add(struct perf_event *event, int flags)
 	if (idx < 0)
 		return idx;
 
-	/*
-	 * If there is an event in the counter we are going to use then make
-	 * sure it is disabled.
-	 */
+	/* The newly-allocated counter should be empty */
+	WARN_ON_ONCE(hw_events->events[idx]);
+
 	event->hw.idx = idx;
-	armpmu->disable(event);
 	hw_events->events[idx] = event;
 
 	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
-- 
2.39.5

[PATCH AUTOSEL 5.4 4/5] xen/mcelog: Add __nonstring annotations for unterminated strings

[Sasha Levin]

From: Kees Cook <kees@kernel.org>

[ Upstream commit 1c3dfc7c6b0f551fdca3f7c1f1e4c73be8adb17d ]

When a character array without a terminating NUL character has a static
initializer, GCC 15's -Wunterminated-string-initialization will only
warn if the array lacks the "nonstring" attribute[1]. Mark the arrays
with __nonstring to and correctly identify the char array as "not a C
string" and thereby eliminate the warning.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: xen-devel@lists.xenproject.org
Signed-off-by: Kees Cook <kees@kernel.org>
Acked-by: Juergen Gross <jgross@suse.com>
Message-ID: <20250310222234.work.473-kees@kernel.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/xen/interface/xen-mca.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/xen/interface/xen-mca.h b/include/xen/interface/xen-mca.h
index 73a4ea714d937..5db6116cd042c 100644
--- a/include/xen/interface/xen-mca.h
+++ b/include/xen/interface/xen-mca.h
@@ -365,7 +365,7 @@ struct xen_mce {
 #define XEN_MCE_LOG_LEN 32
 
 struct xen_mce_log {
-	char signature[12]; /* "MACHINECHECK" */
+	char signature[12] __nonstring; /* "MACHINECHECK" */
 	unsigned len;	    /* = XEN_MCE_LOG_LEN */
 	unsigned next;
 	unsigned flags;
-- 
2.39.5

[PATCH AUTOSEL 5.4 5/5] x86/mm/ident_map: Fix theoretical virtual address overflow to zero

[Sasha Levin]

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

[ Upstream commit f666c92090a41ac5524dade63ff96b3adcf8c2ab ]

The current calculation of the 'next' virtual address in the
page table initialization functions in arch/x86/mm/ident_map.c
doesn't protect against wrapping to zero.

This is a theoretical issue that cannot happen currently,
the problematic case is possible only if the user sets a
high enough x86_mapping_info::offset value - which no
current code in the upstream kernel does.

( The wrapping to zero only occurs if the top PGD entry is accessed.
  There are no such users upstream. Only hibernate_64.c uses
  x86_mapping_info::offset, and it operates on the direct mapping
  range, which is not the top PGD entry. )

Should such an overflow happen, it can result in page table
corruption and a hang.

To future-proof this code, replace the manual 'next' calculation
with p?d_addr_end() which handles wrapping correctly.

[ Backporter's note: there's no need to backport this patch. ]

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20241016111458.846228-2-kirill.shutemov@linux.intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/mm/ident_map.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
index 968d7005f4a72..2f383e288c430 100644
--- a/arch/x86/mm/ident_map.c
+++ b/arch/x86/mm/ident_map.c
@@ -27,9 +27,7 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
 		pud_t *pud = pud_page + pud_index(addr);
 		pmd_t *pmd;
 
-		next = (addr & PUD_MASK) + PUD_SIZE;
-		if (next > end)
-			next = end;
+		next = pud_addr_end(addr, end);
 
 		if (info->direct_gbpages) {
 			pud_t pudval;
@@ -68,10 +66,7 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page,
 		p4d_t *p4d = p4d_page + p4d_index(addr);
 		pud_t *pud;
 
-		next = (addr & P4D_MASK) + P4D_SIZE;
-		if (next > end)
-			next = end;
-
+		next = p4d_addr_end(addr, end);
 		if (p4d_present(*p4d)) {
 			pud = pud_offset(p4d, 0);
 			result = ident_pud_init(info, pud, addr, next);
@@ -113,10 +108,7 @@ int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
 		pgd_t *pgd = pgd_page + pgd_index(addr);
 		p4d_t *p4d;
 
-		next = (addr & PGDIR_MASK) + PGDIR_SIZE;
-		if (next > end)
-			next = end;
-
+		next = pgd_addr_end(addr, end);
 		if (pgd_present(*pgd)) {
 			p4d = p4d_offset(pgd, 0);
 			result = ident_p4d_init(info, p4d, addr, next);
-- 
2.39.5