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| author | Mark Rutland <mark.rutland@arm.com> | 2018-12-07 19:39:27 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2018-12-13 17:42:46 +0100 |
| commit | ccc43810827f9feb5e588e4b7098dc55b1d972f8 (patch) | |
| tree | da4af8576de9d0a0d470a6ec31331f4909667070 /arch/arm64/kernel/perf_callchain.c | |
| parent | arm64: expose user PAC bit positions via ptrace (diff) | |
| download | linux-ccc43810827f9feb5e588e4b7098dc55b1d972f8.tar.xz linux-ccc43810827f9feb5e588e4b7098dc55b1d972f8.zip | |
arm64: perf: strip PAC when unwinding userspace
When the kernel is unwinding userspace callchains, we can't expect that
the userspace consumer of these callchains has the data necessary to
strip the PAC from the stored LR.
This patch has the kernel strip the PAC from user stackframes when the
in-kernel unwinder is used. This only affects the LR value, and not the
FP.
This only affects the in-kernel unwinder. When userspace performs
unwinding, it is up to userspace to strip PACs as necessary (which can
be determined from DWARF information).
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/perf_callchain.c')
| -rw-r--r-- | arch/arm64/kernel/perf_callchain.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c index bcafd7dcfe8b..94754f07f67a 100644 --- a/arch/arm64/kernel/perf_callchain.c +++ b/arch/arm64/kernel/perf_callchain.c @@ -18,6 +18,7 @@ #include <linux/perf_event.h> #include <linux/uaccess.h> +#include <asm/pointer_auth.h> #include <asm/stacktrace.h> struct frame_tail { @@ -35,6 +36,7 @@ user_backtrace(struct frame_tail __user *tail, { struct frame_tail buftail; unsigned long err; + unsigned long lr; /* Also check accessibility of one struct frame_tail beyond */ if (!access_ok(VERIFY_READ, tail, sizeof(buftail))) @@ -47,7 +49,9 @@ user_backtrace(struct frame_tail __user *tail, if (err) return NULL; - perf_callchain_store(entry, buftail.lr); + lr = ptrauth_strip_insn_pac(buftail.lr); + + perf_callchain_store(entry, lr); /* * Frame pointers should strictly progress back up the stack |