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SubjectRe: [patch 04/14] x86/exceptions: Make IST index zero based
On Sun, Mar 31, 2019 at 11:40:24PM +0200, Thomas Gleixner wrote:
> The defines for the exception stack (IST) array in the TSS are using the
> SDM convention IST1 - IST7. That causes all sorts of code to subtract 1 for
> array indices related to IST. That's confusing at best and does not provide
> any value.
>
> Make the indices zero based and fixup the usage sites. The only code which
> needs to adjust the 0 based index is the interrupt descriptor setup which
> needs to add 1 now.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> Documentation/x86/kernel-stacks | 8 ++++----
> arch/x86/entry/entry_64.S | 4 ++--
> arch/x86/include/asm/page_64_types.h | 13 ++++++++-----
> arch/x86/kernel/cpu/common.c | 4 ++--
> arch/x86/kernel/dumpstack_64.c | 14 +++++++-------
> arch/x86/kernel/idt.c | 15 +++++++++------
> 6 files changed, 32 insertions(+), 26 deletions(-)

With the below hunk added:

Reviewed-by: Borislav Petkov <bp@suse.de>

---
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 667f1da36208..1e340adf65e8 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -793,7 +793,7 @@ no_context(struct pt_regs *regs, unsigned long error_code,
if (is_vmalloc_addr((void *)address) &&
(((unsigned long)tsk->stack - 1 - address < PAGE_SIZE) ||
address - ((unsigned long)tsk->stack + THREAD_SIZE) < PAGE_SIZE)) {
- unsigned long stack = this_cpu_read(orig_ist.ist[DOUBLEFAULT_STACK]) - sizeof(void *);
+ unsigned long stack = this_cpu_read(orig_ist.ist[DOUBLEFAULT_IST]) - sizeof(void *);
/*
* We're likely to be running with very little stack space
* left. It's plausible that we'd hit this condition but

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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