The following commit has been merged into the x86/entry branch of tip: Commit-ID: 68a05c6247d2aa67f5ada1009ffd19758e5914ea Gitweb: https://git.kernel.org/tip/68a05c6247d2aa67f5ada1009ffd19758e5914ea Author: Thomas Gleixner <t...@linutronix.de> AuthorDate: Wed, 25 Mar 2020 19:53:38 +01:00 Committer: Thomas Gleixner <t...@linutronix.de> CommitterDate: Tue, 19 May 2020 16:03:52 +02:00
x86/traps: Mark fixup_bad_iret() noinstr This is called from deep entry ASM in a situation where instrumentation will cause more harm than providing useful information. Switch from memmove() to memcpy() because memmove() can't be called from noinstr code. Signed-off-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.char...@oracle.com> Reviewed-by: Masami Hiramatsu <mhira...@kernel.org> Acked-by: Peter Zijlstra <pet...@infradead.org> Acked-by: Andy Lutomirski <l...@kernel.org> Link: https://lkml.kernel.org/r/20200505134903.346741...@linutronix.de --- arch/x86/kernel/traps.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 48468f6..b2b3656 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -578,7 +578,7 @@ struct bad_iret_stack { struct pt_regs regs; }; -asmlinkage __visible notrace +asmlinkage __visible noinstr struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) { /* @@ -589,19 +589,21 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) * just below the IRET frame) and we want to pretend that the * exception came from the IRET target. */ - struct bad_iret_stack *new_stack = - (struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; + struct bad_iret_stack tmp, *new_stack = + (struct bad_iret_stack *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; - /* Copy the IRET target to the new stack. */ - memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); + /* Copy the IRET target to the temporary storage. */ + memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8); /* Copy the remainder of the stack from the current stack. */ - memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); + memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip)); + + /* Update the entry stack */ + memcpy(new_stack, &tmp, sizeof(tmp)); BUG_ON(!user_mode(&new_stack->regs)); return new_stack; } -NOKPROBE_SYMBOL(fixup_bad_iret); #endif static bool is_sysenter_singlestep(struct pt_regs *regs)
