diff options
Diffstat (limited to 'arch/arm64/kernel/perf_callchain.c')
| -rw-r--r-- | arch/arm64/kernel/perf_callchain.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c index b0e03e052dd1..a4b0864c4e32 100644 --- a/arch/arm64/kernel/perf_callchain.c +++ b/arch/arm64/kernel/perf_callchain.c @@ -54,16 +54,22 @@ user_backtrace(struct frame_tail __user *tail, #ifdef CONFIG_COMPAT /* - * The registers we're interested in are at the end of the variable - * length saved register structure. The fp points at the end of this - * structure so the address of this struct is: - * (struct compat_frame_tail *)(xxx->fp)-1 + * The AAPCS ABI, the most current replacing the obsolete APCS ABI, + * does not specifically describe the stack frame with respect to the + * frame pointer. However, the examination of emitted prologue + * instructions for ARM implies that with -fno-omit-framepointer, + * register R11 is used as the frame pointer register and saved on the + * stack, with LR. * - * This code has been adapted from the ARM OProfile support. + * After the prolog, the FP points to the location of the saved LR and + * FP+4 points to the previous frames FP as shown below: + * Stack Hi Mem + * (Value of FP)+4 Saved FP for caller + * (Value of FP) LR set by caller + * Stack Lo Mem */ struct compat_frame_tail { compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */ - u32 sp; u32 lr; } __attribute__((packed)); @@ -91,11 +97,10 @@ compat_user_backtrace(struct compat_frame_tail __user *tail, * Frame pointers should strictly progress back up the stack * (towards higher addresses). */ - if (tail + 1 >= (struct compat_frame_tail __user *) - compat_ptr(buftail.fp)) + if ((u64)tail + 4 >= (u64)buftail.fp) return NULL; - return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1; + return (struct compat_frame_tail __user *)((u64)buftail.fp - 4); } #endif /* CONFIG_COMPAT */ @@ -123,7 +128,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry, /* AARCH32 compat mode */ struct compat_frame_tail __user *tail; - tail = (struct compat_frame_tail __user *)regs->compat_fp - 1; + tail = (struct compat_frame_tail __user *)(regs->compat_fp - 4); while ((entry->nr < entry->max_stack) && tail && !((unsigned long)tail & 0x3)) |