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x86/fpu/signal: Move header zeroing out of xsave_to_user_sigframe()

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There is no reason to have the header zeroing in the pagefault disabled
region. Do it upfront once.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210908132525.621674721@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-09-08 15:29:29 +02:00 committed by Borislav Petkov
parent 4339d0c63c
commit 4164a482a5
2 changed files with 18 additions and 11 deletions
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17
arch/x86/include/asm/fpu/internal.h
View File

@ -318,9 +318,12 @@ static inline void os_xrstor(struct xregs_state *xstate, u64 mask)
* We don't use modified optimization because xrstor/xrstors might track
* a different application.
*
* We don't use compacted format xsave area for
* backward compatibility for old applications which don't understand
* compacted format of xsave area.
* We don't use compacted format xsave area for backward compatibility for
* old applications which don't understand the compacted format of the
* xsave area.
*
* The caller has to zero buf::header before calling this because XSAVE*
* does not touch the reserved fields in the header.
*/
static inline int xsave_to_user_sigframe(struct xregs_state __user *buf)
{
@ -334,14 +337,6 @@ static inline int xsave_to_user_sigframe(struct xregs_state __user *buf)
u32 hmask = mask >> 32;
int err;
/*
* Clear the xsave header first, so that reserved fields are
* initialized to zero.
*/
err = __clear_user(&buf->header, sizeof(buf->header));
if (unlikely(err))
return -EFAULT;
stac();
XSTATE_OP(XSAVE, buf, lmask, hmask, err);
clac();

12
arch/x86/kernel/fpu/signal.c
View File

@ -189,6 +189,18 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
if (!access_ok(buf, size))
return -EACCES;
if (use_xsave()) {
struct xregs_state __user *xbuf = buf_fx;
/*
* Clear the xsave header first, so that reserved fields are
* initialized to zero.
*/
ret = __clear_user(&xbuf->header, sizeof(xbuf->header));
if (unlikely(ret))
return ret;
}
retry:
/*
* Load the FPU registers if they are not valid for the current task.