On Sat, Aug 28 2021 at 22:51, Al Viro wrote:
> @@ -345,7 +346,7 @@ static inline int xsave_to_user_sigframe(struct
> xregs_state __user *buf)
> */
> err = __clear_user(&buf->header, sizeof(buf->header));
> if (unlikely(err))
> - return -EFAULT;
> + return -X86_TRAP_PF;
This clear_user can be lifted into copy_fpstate_to_sigframe(). Something
like the below.
Thanks,
tglx
---
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -135,18 +135,12 @@ static inline int save_xstate_epilog(voi
static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
{
- int err;
-
if (use_xsave())
- err = xsave_to_user_sigframe(buf);
- else if (use_fxsr())
- err = fxsave_to_user_sigframe((struct fxregs_state __user *)
buf);
+ return xsave_to_user_sigframe(buf);
+ if (use_fxsr())
+ return fxsave_to_user_sigframe((struct fxregs_state __user *)
buf);
else
- err = fnsave_to_user_sigframe((struct fregs_state __user *)
buf);
-
- if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
- err = -EFAULT;
- return err;
+ return fnsave_to_user_sigframe((struct fregs_state __user *)
buf);
}
/*
@@ -188,6 +182,16 @@ int copy_fpstate_to_sigframe(void __user
if (!access_ok(buf, size))
return -EACCES;
+
+ if (use_xsave()) {
+ /*
+ * Clear the xsave header first, so that reserved fields are
+ * initialized to zero.
+ */
+ ret = __clear_user(&buf->header, sizeof(buf->header));
+ if (unlikely(ret))
+ return ret;
+ }
retry:
/*
* Load the FPU registers if they are not valid for the current task.
@@ -205,9 +209,10 @@ int copy_fpstate_to_sigframe(void __user
fpregs_unlock();
if (ret) {
- if (!fault_in_pages_writeable(buf_fx, fpu_user_xstate_size))
+ if (!__clear_user(buf_fx, fpu_user_xstate_size) &&
+ ret == -X86_TRAP_PF)
goto retry;
- return -EFAULT;
+ return -1;
}
/* Save the fsave header for the 32-bit frames. */
@@ -275,7 +280,7 @@ static int restore_fpregs_from_user(void
fpregs_unlock();
/* Try to handle #PF, but anything else is fatal. */
- if (ret != -EFAULT)
+ if (ret != -X86_TRAP_PF)
return -EINVAL;
ret = fault_in_pages_readable(buf, size);
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -323,9 +323,12 @@ static inline void os_xrstor(struct xreg
* 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 them.
*/
static inline int xsave_to_user_sigframe(struct xregs_state __user *buf)
{
@@ -339,14 +342,6 @@ static inline int xsave_to_user_sigframe
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();
