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| author | Thomas Gleixner <tglx@linutronix.de> | 2021-09-08 15:29:26 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-09-13 18:26:05 +0200 |
| commit | 4339d0c63c2d5bea1fe6de4091ee2fe9eeea09a7 (patch) | |
| tree | 68310967ab63e1ede2137f5784dab425aa52d089 /arch/x86/kernel/fpu/signal.c | |
| parent | 0c2e62ba04cd0b7194b380bae4fc35c45bb2e46e (diff) | |
| download | linux-4339d0c63c2d5bea1fe6de4091ee2fe9eeea09a7.tar.bz2 | |
x86/fpu/signal: Clarify exception handling in restore_fpregs_from_user()
FPU restore from a signal frame can trigger various exceptions. The
exceptions are caught with an exception table entry. The handler of this
entry stores the trap number in EAX. The FPU specific fixup negates that
trap number to convert it into an negative error code.
Any other exception than #PF is fatal and recovery is not possible. This
relies on the fact that the #PF exception number is the same as EFAULT, but
that's not really obvious.
Remove the negation from the exception fixup as it really has no value and
check for X86_TRAP_PF at the call site.
There is still confusion due to the return code conversion for the error
case which will be cleaned up separately.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210908132525.506192488@linutronix.de
Diffstat (limited to 'arch/x86/kernel/fpu/signal.c')
| -rw-r--r-- | arch/x86/kernel/fpu/signal.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 445c57c9c539..9bfffdb64c0d 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -13,6 +13,7 @@ #include <asm/fpu/xstate.h> #include <asm/sigframe.h> +#include <asm/trapnr.h> #include <asm/trace/fpu.h> static struct _fpx_sw_bytes fx_sw_reserved __ro_after_init; @@ -275,7 +276,7 @@ retry: 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); @@ -405,7 +406,7 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, u64 mask = user_xfeatures | xfeatures_mask_supervisor(); fpu->state.xsave.header.xfeatures &= mask; - ret = os_xrstor_safe(&fpu->state.xsave, xfeatures_mask_all); + ret = os_xrstor_safe(&fpu->state.xsave, xfeatures_mask_all) ? -EINVAL : 0; } else { ret = fxrstor_safe(&fpu->state.fxsave); } |