diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2020-11-11 22:01:51 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-11-19 16:56:52 +1100 |
| commit | 987c426320cce72d1b28f55c8603b239e4f7187c (patch) | |
| tree | b1e9572df774b1b1c48091285984b81b9be874d2 /arch/powerpc/perf/callchain.h | |
| parent | fdcfeaba38e5b183045f5b079af94f97658eabe6 (diff) | |
powerpc/64s/perf: perf interrupt does not have to get_user_pages to access user memory
read_user_stack_slow that walks user address translation by hand is
only required on hash, because a hash fault can not be serviced from
"NMI" context (to avoid re-entering the hash code) so the user stack
can be mapped into Linux page tables but not accessible by the CPU.
Radix MMU mode does not have this restriction. A page fault failure
would indicate the page is not accessible via get_user_pages either,
so avoid this on radix.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201111120151.3150658-1-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/perf/callchain.h')
| -rw-r--r-- | arch/powerpc/perf/callchain.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/perf/callchain.h b/arch/powerpc/perf/callchain.h index ae24d4a00da6..d6fa6e25234f 100644 --- a/arch/powerpc/perf/callchain.h +++ b/arch/powerpc/perf/callchain.h @@ -33,7 +33,7 @@ static inline int __read_user_stack(const void __user *ptr, void *ret, rc = copy_from_user_nofault(ret, ptr, size); - if (IS_ENABLED(CONFIG_PPC64) && rc) + if (IS_ENABLED(CONFIG_PPC64) && !radix_enabled() && rc) return read_user_stack_slow(ptr, ret, size); return rc; |