From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] powerpc/signal32: Force inlining of __unsafe_save_user_regs() and save_tm_user_regs_unsafe()
Date: Mon, 5 Jun 2023 10:58:35 +0200 [thread overview]
Message-ID: <7e469c8f01860a69c1ada3ca6a5e2aa65f0f74b2.1685955220.git.christophe.leroy@csgroup.eu> (raw)
Looking at generated code for handle_signal32() shows calls to a
function called __unsafe_save_user_regs.constprop.0 while user access
is open.
And that __unsafe_save_user_regs.constprop.0 function has two nops at
the begining, allowing it to be traced, which is unexpected during
user access open window.
The solution could be to mark __unsafe_save_user_regs() no trace, but
to be on the safe side the most efficient is to flag it __always_inline
as already done for function __unsafe_restore_general_regs(). The
function is relatively small and only called twice, so the size
increase will remain in the noise.
Do the same with save_tm_user_regs_unsafe() as it may suffer the
same issue.
Fixes: ef75e7318294 ("powerpc/signal32: Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/signal_32.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index c114c7f25645..7a718ed32b27 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -264,8 +264,9 @@ static void prepare_save_user_regs(int ctx_has_vsx_region)
#endif
}
-static int __unsafe_save_user_regs(struct pt_regs *regs, struct mcontext __user *frame,
- struct mcontext __user *tm_frame, int ctx_has_vsx_region)
+static __always_inline int
+__unsafe_save_user_regs(struct pt_regs *regs, struct mcontext __user *frame,
+ struct mcontext __user *tm_frame, int ctx_has_vsx_region)
{
unsigned long msr = regs->msr;
@@ -364,8 +365,9 @@ static void prepare_save_tm_user_regs(void)
current->thread.ckvrsave = mfspr(SPRN_VRSAVE);
}
-static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
- struct mcontext __user *tm_frame, unsigned long msr)
+static __always_inline int
+save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
+ struct mcontext __user *tm_frame, unsigned long msr)
{
/* Save both sets of general registers */
unsafe_save_general_regs(¤t->thread.ckpt_regs, frame, failed);
@@ -444,8 +446,9 @@ static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user
#else
static void prepare_save_tm_user_regs(void) { }
-static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
- struct mcontext __user *tm_frame, unsigned long msr)
+static __always_inline int
+save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
+ struct mcontext __user *tm_frame, unsigned long msr)
{
return 0;
}
--
2.40.1
WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc/signal32: Force inlining of __unsafe_save_user_regs() and save_tm_user_regs_unsafe()
Date: Mon, 5 Jun 2023 10:58:35 +0200 [thread overview]
Message-ID: <7e469c8f01860a69c1ada3ca6a5e2aa65f0f74b2.1685955220.git.christophe.leroy@csgroup.eu> (raw)
Looking at generated code for handle_signal32() shows calls to a
function called __unsafe_save_user_regs.constprop.0 while user access
is open.
And that __unsafe_save_user_regs.constprop.0 function has two nops at
the begining, allowing it to be traced, which is unexpected during
user access open window.
The solution could be to mark __unsafe_save_user_regs() no trace, but
to be on the safe side the most efficient is to flag it __always_inline
as already done for function __unsafe_restore_general_regs(). The
function is relatively small and only called twice, so the size
increase will remain in the noise.
Do the same with save_tm_user_regs_unsafe() as it may suffer the
same issue.
Fixes: ef75e7318294 ("powerpc/signal32: Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/signal_32.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index c114c7f25645..7a718ed32b27 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -264,8 +264,9 @@ static void prepare_save_user_regs(int ctx_has_vsx_region)
#endif
}
-static int __unsafe_save_user_regs(struct pt_regs *regs, struct mcontext __user *frame,
- struct mcontext __user *tm_frame, int ctx_has_vsx_region)
+static __always_inline int
+__unsafe_save_user_regs(struct pt_regs *regs, struct mcontext __user *frame,
+ struct mcontext __user *tm_frame, int ctx_has_vsx_region)
{
unsigned long msr = regs->msr;
@@ -364,8 +365,9 @@ static void prepare_save_tm_user_regs(void)
current->thread.ckvrsave = mfspr(SPRN_VRSAVE);
}
-static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
- struct mcontext __user *tm_frame, unsigned long msr)
+static __always_inline int
+save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
+ struct mcontext __user *tm_frame, unsigned long msr)
{
/* Save both sets of general registers */
unsafe_save_general_regs(¤t->thread.ckpt_regs, frame, failed);
@@ -444,8 +446,9 @@ static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user
#else
static void prepare_save_tm_user_regs(void) { }
-static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
- struct mcontext __user *tm_frame, unsigned long msr)
+static __always_inline int
+save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame,
+ struct mcontext __user *tm_frame, unsigned long msr)
{
return 0;
}
--
2.40.1
next reply other threads:[~2023-06-05 8:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-05 8:58 Christophe Leroy [this message]
2023-06-05 8:58 ` [PATCH] powerpc/signal32: Force inlining of __unsafe_save_user_regs() and save_tm_user_regs_unsafe() Christophe Leroy
2023-06-06 8:58 ` Nicholas Piggin
2023-06-06 8:58 ` Nicholas Piggin
2023-06-09 13:06 ` Michael Ellerman
2023-06-09 13:06 ` Michael Ellerman
2023-07-03 5:26 ` Michael Ellerman
2023-07-03 5:26 ` Michael Ellerman
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