linux-kernel - [PATCH v5 5/5] powerpc/signal: Use unsafe_copy_siginfo_to

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Message-Id: <e0b6740876dd1e08704cabe4946516af43742a4b.1631861883.git.christophe.leroy@csgroup.eu>
Date:   Fri, 17 Sep 2021 08:59:20 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, ebiederm@...ssion.com,
        hch@...radead.org
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v5 5/5] powerpc/signal: Use unsafe_copy_siginfo_to_user()

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@...roup.eu>
---
v5: Added missing __user flag when calling unsafe_copy_siginfo_to_user()

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()
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 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..0baf3c10b6c0 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 __user *)&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