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Subject[RFC][PATCH 14/22] x86: ia32_setup_frame(): consolidate uaccess areas
Date
From: Al Viro <viro@zeniv.linux.org.uk>

Currently we have user_access block, followed by __put_user(),
deciding what the restorer will be and finally a put_user_try
block.

Moving the calculation of restorer first allows the rest
(actual copyout work) to coalesce into a single user_access block.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/x86/ia32/ia32_signal.c | 41 +++++++++++++----------------------------
1 file changed, 13 insertions(+), 28 deletions(-)

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index aedf9929f2b9..4dae24f42e1a 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -229,7 +229,6 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
{
struct sigframe_ia32 __user *frame;
void __user *restorer;
- int err = 0;
void __user *fpstate = NULL;

/* copy_to_user optimizes that into a single 8 byte store */
@@ -245,22 +244,6 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,

frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);

- if (!access_ok(frame, sizeof(*frame)))
- return -EFAULT;
-
- if (__put_user(sig, &frame->sig))
- return -EFAULT;
-
- if (!user_access_begin(&frame->sc, sizeof(struct sigcontext_32)))
- return -EFAULT;
-
- if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
- goto Efault;
- user_access_end();
-
- if (__put_user(set->sig[1], &frame->extramask[0]))
- return -EFAULT;
-
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
restorer = ksig->ka.sa.sa_restorer;
} else {
@@ -272,19 +255,21 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
restorer = &frame->retcode;
}

- put_user_try {
- put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
-
- /*
- * These are actually not used anymore, but left because some
- * gdb versions depend on them as a marker.
- */
- put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
- } put_user_catch(err);
-
- if (err)
+ if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;

+ unsafe_put_user(sig, &frame->sig, Efault);
+ if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
+ goto Efault;
+ unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
+ unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
+ /*
+ * These are actually not used anymore, but left because some
+ * gdb versions depend on them as a marker.
+ */
+ unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
+ user_access_end();
+
/* Set up registers for signal handler */
regs->sp = (unsigned long) frame;
regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
--
2.11.0
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