The following commit has been merged into the x86/entry branch of tip: Commit-ID: f44e70325748c7998cf089d2ae67b4b5bc8d8ad9 Gitweb: https://git.kernel.org/tip/f44e70325748c7998cf089d2ae67b4b5bc8d8ad9 Author: Peter Zijlstra <[email protected]> AuthorDate: Thu, 20 Feb 2020 13:17:27 +01:00 Committer: Thomas Gleixner <[email protected]> CommitterDate: Fri, 15 May 2020 20:03:04 +02:00
x86/doublefault: Remove memmove() call Use of memmove() in #DF is problematic considered tracing and other instrumentation. Remove the memmove() call and simply write out what needs doing; this even clarifies the code, win-win! The code copies from the espfix64 stack to the normal task stack, there is no possible way for that to overlap. Survives selftests/x86, specifically sigreturn_64. Suggested-by: Borislav Petkov <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Andy Lutomirski <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- arch/x86/kernel/traps.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e85561f..75fa765 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -369,6 +369,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign regs->ip == (unsigned long)native_irq_return_iret) { struct pt_regs *gpregs = (struct pt_regs *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; + unsigned long *p = (unsigned long *)regs->sp; /* * regs->sp points to the failing IRET frame on the @@ -376,7 +377,11 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign * in gpregs->ss through gpregs->ip. * */ - memmove(&gpregs->ip, (void *)regs->sp, 5*8); + gpregs->ip = p[0]; + gpregs->cs = p[1]; + gpregs->flags = p[2]; + gpregs->sp = p[3]; + gpregs->ss = p[4]; gpregs->orig_ax = 0; /* Missing (lost) #GP error code */ /*
