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 <t...@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(-) > > --- a/Documentation/x86/kernel-stacks > +++ b/Documentation/x86/kernel-stacks > @@ -59,7 +59,7 @@ If that assumption is ever broken then t > > The currently assigned IST stacks are :- > > -* DOUBLEFAULT_STACK. EXCEPTION_STKSZ (PAGE_SIZE). > +* DOUBLEFAULT_IST. EXCEPTION_STKSZ (PAGE_SIZE). > > Used for interrupt 8 - Double Fault Exception (#DF). > > @@ -68,7 +68,7 @@ The currently assigned IST stacks are :- > Using a separate stack allows the kernel to recover from it well enough > in many cases to still output an oops. > > -* NMI_STACK. EXCEPTION_STKSZ (PAGE_SIZE). > +* NMI_IST. EXCEPTION_STKSZ (PAGE_SIZE). > > Used for non-maskable interrupts (NMI). > > @@ -76,7 +76,7 @@ The currently assigned IST stacks are :- > middle of switching stacks. Using IST for NMI events avoids making > assumptions about the previous state of the kernel stack. > > -* DEBUG_STACK. DEBUG_STKSZ > +* DEBUG_IST. DEBUG_STKSZ
What about <name>_STACK_IST, or is that too verbose? It'd be nice to have the extra mental cue that IST is referring the 64 exception stacks. > > Used for hardware debug interrupts (interrupt 1) and for software > debug interrupts (INT3). > @@ -86,7 +86,7 @@ The currently assigned IST stacks are :- > avoids making assumptions about the previous state of the kernel > stack. > > -* MCE_STACK. EXCEPTION_STKSZ (PAGE_SIZE). > +* MCE_IST. EXCEPTION_STKSZ (PAGE_SIZE). > > Used for interrupt 18 - Machine Check Exception (#MC). >
