[PATCH v4 5/5] powerpc/signal: Use unsafe_copy_siginfo_to_user()

From: Christophe Leroy
Date: Tue Sep 14 2021 - 10:32:10 EST


Use unsafe_copy_siginfo_to_user() in order to do the copy
within the user access block.

On an mpc 8321 (book3s/32) the improvment is about 5% on a process
sending a signal to itself.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
v4: Use another approach for compat: drop the unsafe_copy_siginfo_to_user32(), instead directly call copy_siginfo_to_external32() before user_access_begin()

v3: Don't leave compat aside, use the new unsafe_copy_siginfo_to_user32()
---
arch/powerpc/kernel/signal_32.c | 17 ++++++++---------
arch/powerpc/kernel/signal_64.c | 5 +----
2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index ff101e2b3bab..f1f5dde0885f 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -710,12 +710,6 @@ static long restore_tm_user_regs(struct pt_regs *regs, struct mcontext __user *s
}
#endif

-#ifdef CONFIG_PPC64
-
-#define copy_siginfo_to_user copy_siginfo_to_user32
-
-#endif /* CONFIG_PPC64 */
-
/*
* Set up a signal frame for a "real-time" signal handler
* (one which gets siginfo).
@@ -731,6 +725,7 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
struct pt_regs *regs = tsk->thread.regs;
/* Save the thread's msr before get_tm_stackpointer() changes it */
unsigned long msr = regs->msr;
+ compat_siginfo_t uinfo;

/* Set up Signal Frame */
frame = get_sigframe(ksig, tsk, sizeof(*frame), 1);
@@ -744,6 +739,9 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
else
prepare_save_user_regs(1);

+ if (IS_ENABLED(CONFIG_COMPAT))
+ copy_siginfo_to_external32(&uinfo, &ksig->info);
+
if (!user_access_begin(newsp, __SIGNAL_FRAMESIZE + 16 + sizeof(*frame)))
goto badframe;

@@ -779,15 +777,16 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
asm("dcbst %y0; sync; icbi %y0; sync" :: "Z" (mctx->mc_pad[0]));
}
unsafe_put_sigset_t(&frame->uc.uc_sigmask, oldset, failed);
+ if (IS_ENABLED(CONFIG_COMPAT))
+ unsafe_copy_to_user(&frame->info, &uinfo, sizeof(frame->info), failed);
+ else
+ unsafe_copy_siginfo_to_user((void *)&frame->info, &ksig->info, failed);

/* create a stack frame for the caller of the handler */
unsafe_put_user(regs->gpr[1], newsp, failed);

user_access_end();

- if (copy_siginfo_to_user(&frame->info, &ksig->info))
- goto badframe;
-
regs->link = tramp;

#ifdef CONFIG_PPC_FPU_REGS
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index d80ff83cacb9..56c0c74aa28c 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -901,15 +901,12 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
}

unsafe_copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set), badframe_block);
+ unsafe_copy_siginfo_to_user(&frame->info, &ksig->info, badframe_block);
/* Allocate a dummy caller frame for the signal handler. */
unsafe_put_user(regs->gpr[1], newsp, badframe_block);

user_write_access_end();

- /* Save the siginfo outside of the unsafe block. */
- if (copy_siginfo_to_user(&frame->info, &ksig->info))
- goto badframe;
-
/* Make sure signal handler doesn't get spurious FP exceptions */
tsk->thread.fp_state.fpscr = 0;

--
2.31.1