Sampled Data Address Register (SDAR) is a 64-bit
register that contains the effective address of
the storage operand of an instruction that was
being executed, possibly out-of-order, at or around
the time that the Performance Monitor alert occurred.
In certain scenario SDAR happen to contain the kernel
address even for userspace only sampling. Add checks
to prevent it.
Signed-off-by: Madhavan Srinivasan <ma...@linux.vnet.ibm.com>
---
Changelog v1:
- Removed the event exclusive_ check. Will take it up in a separate patch
arch/powerpc/perf/core-book3s.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index f89bbd54ecec..e143f85a4098 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -95,7 +95,7 @@ static inline unsigned long perf_ip_adjust(struct pt_regs
*regs)
{
return 0;
}
-static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp) { }
+static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp, struct
perf_event *event) { }
static inline u32 perf_get_misc_flags(struct pt_regs *regs)
{
return 0;
@@ -174,7 +174,7 @@ static inline unsigned long perf_ip_adjust(struct pt_regs
*regs)
* pointed to by SIAR; this is indicated by the [POWER6_]MMCRA_SDSYNC, the
* [POWER7P_]MMCRA_SDAR_VALID bit in MMCRA, or the SDAR_VALID bit in SIER.
*/
-static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp)
+static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp, struct
perf_event *event)
{
unsigned long mmcra = regs->dsisr;
bool sdar_valid;
@@ -198,6 +198,10 @@ static inline void perf_get_data_addr(struct pt_regs
*regs, u64 *addrp)
if (!(mmcra & MMCRA_SAMPLE_ENABLE) || sdar_valid)
*addrp = mfspr(SPRN_SDAR);
+
+ if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN) &&
+ is_kernel_addr(mfspr(SPRN_SDAR)))
+ *addrp = 0;
}
static bool regs_sihv(struct pt_regs *regs)
@@ -2050,7 +2054,7 @@ static void record_and_restart(struct perf_event *event,
unsigned long val,
if (event->attr.sample_type &
(PERF_SAMPLE_ADDR | PERF_SAMPLE_PHYS_ADDR))
- perf_get_data_addr(regs, &data.addr);
+ perf_get_data_addr(regs, &data.addr, event);
if (event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK) {
struct cpu_hw_events *cpuhw;
--
2.7.4
