Messages in this thread Patch in this message | | | From | Thomas Gleixner <> | Subject | [patch 03/10] x86/fpu/signal: Move xstate clearing out of copy_fpregs_to_sigframe() | Date | Mon, 30 Aug 2021 18:27:25 +0200 (CEST) |
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When the direct saving of the FPU registers to the user space sigframe fails, copy_fpregs_to_sigframe() attempts to clear the user buffer.
The most likely reason for such a fail is a page fault. As copy_fpregs_to_sigframe() is invoked with pagefaults disabled the chance that __clear_user() succeeds is minuscule.
Move the clearing out into the caller which replaces the fault_in_pages_writeable() in that error handling path.
The return value confusion will be cleaned up separately.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kernel/fpu/signal.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-)
--- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -136,18 +136,12 @@ 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); } /* @@ -218,9 +212,10 @@ 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. */
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