Messages in this thread Patch in this message | | | From | Christophe Leroy <> | Subject | [RFC PATCH v1 18/19] powerpc/signal32: Add and use unsafe_put_sigset_t() | Date | Wed, 12 Aug 2020 12:06:10 +0000 (UTC) |
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put_sigset_t() calls copy_to_user() for copying two words.
Because INLINE_COPY_TO_USER is not defined on powerpc, copy_to_user() doesn't get optimised and falls back to copy_tofrom_user() with the relevant glue. This is terribly inefficient for copying two words.
By switching to unsafe_put_user(), we end up with something as simple as:
3cc: 81 3d 00 00 lwz r9,0(r29) 3d0: 91 26 00 b4 stw r9,180(r6) 3d4: 81 3d 00 04 lwz r9,4(r29) 3d8: 91 26 00 b8 stw r9,184(r6)
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- arch/powerpc/kernel/signal_32.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index d03ba3d8eb68..6cbff0293ff4 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -87,6 +87,8 @@ static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set) return put_compat_sigset(uset, set, sizeof(*uset)); } +#define unsafe_put_sigset_t unsafe_put_compat_sigset + static inline int get_sigset_t(sigset_t *set, const compat_sigset_t __user *uset) { @@ -143,6 +145,13 @@ static inline int put_sigset_t(sigset_t __user *uset, sigset_t *set) return copy_to_user(uset, set, sizeof(*uset)); } +#define unsafe_put_sigset_t(uset, set, label) do { \ + sigset_t __user *__us = uset ; \ + const sigset_t *__s = set; \ + \ + unsafe_copy_to_user(__us, __s, sizeof(*__us), label); \ +} while (0) + static inline int get_sigset_t(sigset_t *set, const sigset_t __user *uset) { return copy_from_user(set, uset, sizeof(*uset)); @@ -820,10 +829,11 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset, { unsafe_put_user(0, &rt_sf->uc.uc_link, failed); } + + unsafe_put_sigset_t(&rt_sf->uc.uc_sigmask, oldset, failed); + user_write_access_end(); - if (put_sigset_t(&rt_sf->uc.uc_sigmask, oldset)) - goto badframe; if (copy_siginfo_to_user(&rt_sf->info, &ksig->info)) goto badframe; -- 2.25.0
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