"Christopher M. Riedl" <c...@codefail.de> a écrit :
Usually sigset_t is exactly 8B which is a "trivial" size and does not
warrant using __copy_from_user(). Use __get_user() directly in
anticipation of future work to remove the trivial size optimizations
from __copy_from_user(). Calling __get_user() also results in a small
boost to signal handling throughput here.
Signed-off-by: Christopher M. Riedl <c...@codefail.de>
---
arch/powerpc/kernel/signal_64.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/signal_64.c
b/arch/powerpc/kernel/signal_64.c
index 817b64e1e409..42fdc4a7ff72 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -97,6 +97,14 @@ static void prepare_setup_sigcontext(struct
task_struct *tsk, int ctx_has_vsx_re
#endif /* CONFIG_VSX */
}
+static inline int get_user_sigset(sigset_t *dst, const sigset_t *src)
Should be called __get_user_sigset() as it is a helper for __get_user()
+{
+ if (sizeof(sigset_t) <= 8)
We should always use __get_user(), see below.
+ return __get_user(dst->sig[0], &src->sig[0]);
I think the above will not work on ppc32, it will only copy 4 bytes.
You must cast the source to u64*
+ else
+ return __copy_from_user(dst, src, sizeof(sigset_t));
I see no point in keeping this alternative. Today sigset_ t is fixed.
If you fear one day someone might change it to something different
than a u64, just add a BUILD_BUG_ON(sizeof(sigset_t) != sizeof(u64));
+}
+
/*
* Set up the sigcontext for the signal frame.
*/
@@ -701,8 +709,9 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext
__user *, old_ctx,
* We kill the task with a SIGSEGV in this situation.
*/
- if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))
+ if (get_user_sigset(&set, &new_ctx->uc_sigmask))
do_exit(SIGSEGV);
+
This white space is not part of the change, keep patches to the
minimum, avoid cosmetic
set_current_blocked(&set);
if (!user_read_access_begin(new_ctx, ctx_size))
@@ -740,8 +749,9 @@ SYSCALL_DEFINE0(rt_sigreturn)
if (!access_ok(uc, sizeof(*uc)))
goto badframe;
- if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
+ if (get_user_sigset(&set, &uc->uc_sigmask))
goto badframe;
+
Same
set_current_blocked(&set);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
--
2.26.1
