linux/arch
Denys Vlasenko d828c71fba x86/asm/entry/32: Document the 32-bit SYSENTER "emergency stack" better
Before the patch, the 'tss_struct::stack' field was not referenced anywhere.

It was used only to set SYSENTER's stack to point after the last byte
of tss_struct, thus the trailing field, stack[64], was used.

But grep would not know it. You can comment it out, compile,
and kernel will even run until an unlucky NMI corrupts
io_bitmap[] (which is also not easily detectable).

This patch changes code so that the purpose and usage of this
field is not mysterious anymore, and can be easily grepped for.

This does change generated code, for a subtle reason:
since tss_struct is ____cacheline_aligned, there happens to be
5 longs of padding at the end. Old code was using the padding
too; new code will strictly use it only for SYSENTER_stack[].

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1425912738-559-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-17 09:25:29 +01:00
..
alpha asm-generic: uaccess.h cleanup 2015-02-18 10:02:24 -08:00
arc Merge branch 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma 2015-02-18 08:49:20 -08:00
arm Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-03-01 12:00:25 -08:00
arm64 ARM: SoC fixes for 3.20-rc1 2015-02-27 16:18:33 -08:00
avr32 asm-generic: uaccess.h cleanup 2015-02-18 10:02:24 -08:00
blackfin Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2015-02-21 12:59:04 -08:00
c6x all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
cris CRIS changes for 3.20 2015-02-15 18:02:02 -08:00
frv mm: add missing __PAGETABLE_{PUD,PMD}_FOLDED defines 2015-02-28 09:57:51 -08:00
hexagon all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
ia64 asm-generic: uaccess.h cleanup 2015-02-18 10:02:24 -08:00
m32r mm: add missing __PAGETABLE_{PUD,PMD}_FOLDED defines 2015-02-28 09:57:51 -08:00
m68k mm: add missing __PAGETABLE_{PUD,PMD}_FOLDED defines 2015-02-28 09:57:51 -08:00
metag metag: Fix KSTK_EIP() and KSTK_ESP() macros 2015-02-24 12:54:21 +00:00
microblaze all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
mips Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2015-02-21 19:41:38 -08:00
mn10300 mm: add missing __PAGETABLE_{PUD,PMD}_FOLDED defines 2015-02-28 09:57:51 -08:00
nios2 nios2 for v3.20 2015-02-17 14:23:42 -08:00
openrisc asm-generic: uaccess.h cleanup 2015-02-18 10:02:24 -08:00
parisc mm: add missing __PAGETABLE_{PUD,PMD}_FOLDED defines 2015-02-28 09:57:51 -08:00
powerpc The clock framework changes for 3.20 contain the usual driver additions, 2015-02-21 12:30:30 -08:00
s390 mm: add missing __PAGETABLE_{PUD,PMD}_FOLDED defines 2015-02-28 09:57:51 -08:00
score all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
sh asm-generic: uaccess.h cleanup 2015-02-18 10:02:24 -08:00
sparc asm-generic: uaccess.h cleanup 2015-02-18 10:02:24 -08:00
tile tile: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
um all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
unicore32 mm: vmalloc: pass additional vm_flags to __vmalloc_node_range() 2015-02-13 21:21:42 -08:00
x86 x86/asm/entry/32: Document the 32-bit SYSENTER "emergency stack" better 2015-03-17 09:25:29 +01:00
xtensa asm-generic: uaccess.h cleanup 2015-02-18 10:02:24 -08:00
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