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x86: ia32_setup_frame(): consolidate uaccess areas 

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>
This commit is contained in:
Al Viro 2020-02-15 19:36:40 -05:00
parent 44a1d99632
commit e239074105
1 changed files with 12 additions and 27 deletions
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39
arch/x86/ia32/ia32_signal.c
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@ -236,7 +236,6 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
{
struct sigframe_ia32 __user *frame;
void __user *restorer;
int err = 0;
void __user *fp = NULL;
/* copy_to_user optimizes that into a single 8 byte store */
@ -252,21 +251,6 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
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;
unsafe_put_sigcontext32(&frame->sc, fp, regs, set, 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 {
@ -278,19 +262,20 @@ 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);
unsafe_put_sigcontext32(&frame->sc, fp, regs, set, 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;