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SubjectRe: [PATCH 11/16] x86/asm/64: Use a percpu trampoline stack for IDT entries

* Andy Lutomirski <luto@kernel.org> wrote:

> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 1ea03027a4a9..e4a941be96cf 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c

> -asmlinkage __visible notrace
> +asmlinkage __visible notrace __no_sanitize_address
> struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
> {
> /*
> * This is called from entry_64.S early in handling a fault
> * caused by a bad iret to user mode. To handle the fault
> - * correctly, we want move our stack frame to task_pt_regs
> - * and we want to pretend that the exception came from the
> - * iret target.
> + * correctly, we want move our stack frame to where it would
> + * be had we entered directly on the entry stack (rather than
> + * just below the IRET frame) and we want to pretend that the
> + * exception came from the iret target.
> */
> struct bad_iret_stack *new_stack =
> - container_of(task_pt_regs(current),
> - struct bad_iret_stack, regs);
> + (struct bad_iret_stack *)this_cpu_read(cpu_tss.x86_tss.sp0) - 1;
>
> /* Copy the IRET target to the new stack. */
> memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);

So the addition of the __no_sanitize_address attribute to fixup_bad_iret() made
the 64-bit allyesconfig/allmodconfig kernels fail the build:

In file included from ./include/linux/bitmap.h:9:0,
arch/x86/kernel/traps.c: In function ‘fixup_bad_iret’:
./include/linux/string.h:344:24: error: inlining failed in call to always_inline
‘memmove’: function attribute mismatch
__FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size)
arch/x86/kernel/traps.c:645:2: error: called from here
In file included from ./include/linux/bitmap.h:9:0,
./include/linux/string.h:344:24: error: inlining failed in call to always_inline
‘memmove’: function attribute mismatch
__FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size)
arch/x86/kernel/traps.c:642:2: error: called from here
scripts/Makefile.build:314: recipe for target 'arch/x86/kernel/traps.o' failed

Thanks,

Ingo

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