6.6-stable review patch. If anyone has any objections, please let me know.
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From: Athira Rajeev atrajeev@linux.vnet.ibm.com
[ Upstream commit 2ffb26afa64261139e608bf087a0c1fe24d76d4d ]
perf mem report aborts as below sometimes (during some corner case) in powerpc:
# ./perf mem report 1>out *** stack smashing detected ***: terminated Aborted (core dumped)
The backtrace is as below: __pthread_kill_implementation () raise () abort () __libc_message __fortify_fail __stack_chk_fail hist_entry.lvl_snprintf __sort__hpp_entry __hist_entry__snprintf hists.fprintf cmd_report cmd_mem
Snippet of code which triggers the issue from tools/perf/util/sort.c
static int hist_entry__lvl_snprintf(struct hist_entry *he, char *bf, size_t size, unsigned int width) { char out[64];
perf_mem__lvl_scnprintf(out, sizeof(out), he->mem_info); return repsep_snprintf(bf, size, "%-*s", width, out); }
The value of "out" is filled from perf_mem_data_src value. Debugging this further showed that for some corner cases, the value of "data_src" was pointing to wrong value. This resulted in bigger size of string and causing stack check fail.
The perf mem data source values are captured in the sample via isa207_get_mem_data_src function. The initial check is to fetch the type of sampled instruction. If the type of instruction is not valid (not a load/store instruction), the function returns.
Since 'commit e16fd7f2cb1a ("perf: Use sample_flags for data_src")', data_src field is not initialized by the perf_sample_data_init() function. If the PMU driver doesn't set the data_src value to zero if type is not valid, this will result in uninitailised value for data_src. The uninitailised value of data_src resulted in stack check fail followed by abort for "perf mem report".
When requesting for data source information in the sample, the instruction type is expected to be load or store instruction. In ISA v3.0, due to hardware limitation, there are corner cases where the instruction type other than load or store is observed. In ISA v3.0 and before values "0" and "7" are considered reserved. In ISA v3.1, value "7" has been used to indicate "larx/stcx". Drop the sample if instruction type has reserved values for this field with a ISA version check. Initialize data_src to zero in isa207_get_mem_data_src if the instruction type is not load/store.
Reported-by: Disha Goel disgoel@linux.vnet.ibm.com Signed-off-by: Athira Rajeev atrajeev@linux.vnet.ibm.com Signed-off-by: Madhavan Srinivasan maddy@linux.ibm.com Link: https://patch.msgid.link/20250121131621.39054-1-atrajeev@linux.vnet.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/perf/core-book3s.c | 20 ++++++++++++++++++++ arch/powerpc/perf/isa207-common.c | 4 +++- 2 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 10b946e9c6e75..4bb84dc4393fc 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -2229,6 +2229,10 @@ static struct pmu power_pmu = { #define PERF_SAMPLE_ADDR_TYPE (PERF_SAMPLE_ADDR | \ PERF_SAMPLE_PHYS_ADDR | \ PERF_SAMPLE_DATA_PAGE_SIZE) + +#define SIER_TYPE_SHIFT 15 +#define SIER_TYPE_MASK (0x7ull << SIER_TYPE_SHIFT) + /* * A counter has overflowed; update its count and record * things if requested. Note that interrupts are hard-disabled @@ -2297,6 +2301,22 @@ static void record_and_restart(struct perf_event *event, unsigned long val, is_kernel_addr(mfspr(SPRN_SIAR))) record = 0;
+ /* + * SIER[46-48] presents instruction type of the sampled instruction. + * In ISA v3.0 and before values "0" and "7" are considered reserved. + * In ISA v3.1, value "7" has been used to indicate "larx/stcx". + * Drop the sample if "type" has reserved values for this field with a + * ISA version check. + */ + if (event->attr.sample_type & PERF_SAMPLE_DATA_SRC && + ppmu->get_mem_data_src) { + val = (regs->dar & SIER_TYPE_MASK) >> SIER_TYPE_SHIFT; + if (val == 0 || (val == 7 && !cpu_has_feature(CPU_FTR_ARCH_31))) { + record = 0; + atomic64_inc(&event->lost_samples); + } + } + /* * Finally record data if requested. */ diff --git a/arch/powerpc/perf/isa207-common.c b/arch/powerpc/perf/isa207-common.c index 56301b2bc8ae8..031a2b63c171d 100644 --- a/arch/powerpc/perf/isa207-common.c +++ b/arch/powerpc/perf/isa207-common.c @@ -321,8 +321,10 @@ void isa207_get_mem_data_src(union perf_mem_data_src *dsrc, u32 flags,
sier = mfspr(SPRN_SIER); val = (sier & ISA207_SIER_TYPE_MASK) >> ISA207_SIER_TYPE_SHIFT; - if (val != 1 && val != 2 && !(val == 7 && cpu_has_feature(CPU_FTR_ARCH_31))) + if (val != 1 && val != 2 && !(val == 7 && cpu_has_feature(CPU_FTR_ARCH_31))) { + dsrc->val = 0; return; + }
idx = (sier & ISA207_SIER_LDST_MASK) >> ISA207_SIER_LDST_SHIFT; sub_idx = (sier & ISA207_SIER_DATA_SRC_MASK) >> ISA207_SIER_DATA_SRC_SHIFT;