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x86/entry: Restore traditional SYSENTER calling convention

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It turns out that some Android versions hardcode the SYSENTER
calling convention.  This is buggy and will cause problems no
matter what the kernel does.  Nonetheless, we should try to
support it.

Credit goes to Linus for pointing out a clean way to handle
the SYSENTER/SYSCALL clobber differences while preserving
straightforward DWARF annotations.

I believe that the original offending Android commit was:

https://android.googlesource.com/platform%2Fbionic/+/7dc3684d7a2587e43e6d2a8e0e3f39bf759bd535

Reported-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-and-tested-by: Borislav Petkov <bp@alien8.de>
Cc: <mark.gross@intel.com>
Cc: Su Tao <tao.su@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: <frank.wang@intel.com>
Cc: <borun.fu@intel.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Mingwei Shi <mingwei.shi@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Andy Lutomirski
2015-12-16 23:18:48 -08:00
committed by Thomas Gleixner
parent 6a613ac6bc
commit 30bfa7b348
4 changed files with 52 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
arch/x86/entry/entry_64_compat.S
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@@ -63,7 +63,7 @@ ENTRY(entry_SYSENTER_compat)
/* Construct struct pt_regs on stack */
pushq $__USER32_DS /* pt_regs->ss */
pushq %rcx /* pt_regs->sp */
pushq %rbp /* pt_regs->sp (stashed in bp) */
/*
* Push flags. This is nasty. First, interrupts are currently
@@ -82,14 +82,14 @@ ENTRY(entry_SYSENTER_compat)
pushq %rdi /* pt_regs->di */
pushq %rsi /* pt_regs->si */
pushq %rdx /* pt_regs->dx */
pushq %rcx /* pt_regs->cx (will be overwritten) */
pushq %rcx /* pt_regs->cx */
pushq $-ENOSYS /* pt_regs->ax */
pushq %r8 /* pt_regs->r8 = 0 */
pushq %r8 /* pt_regs->r9 = 0 */
pushq %r8 /* pt_regs->r10 = 0 */
pushq %r8 /* pt_regs->r11 = 0 */
pushq %rbx /* pt_regs->rbx */
pushq %rbp /* pt_regs->rbp */
pushq %rbp /* pt_regs->rbp (will be overwritten) */
pushq %r8 /* pt_regs->r12 = 0 */
pushq %r8 /* pt_regs->r13 = 0 */
pushq %r8 /* pt_regs->r14 = 0 */
@@ -179,7 +179,7 @@ ENTRY(entry_SYSCALL_compat)
pushq %rdi /* pt_regs->di */
pushq %rsi /* pt_regs->si */
pushq %rdx /* pt_regs->dx */
pushq %rcx /* pt_regs->cx (will be overwritten) */
pushq %rbp /* pt_regs->cx (stashed in bp) */
pushq $-ENOSYS /* pt_regs->ax */
xorq %r8,%r8
pushq %r8 /* pt_regs->r8 = 0 */
@@ -187,7 +187,7 @@ ENTRY(entry_SYSCALL_compat)
pushq %r8 /* pt_regs->r10 = 0 */
pushq %r8 /* pt_regs->r11 = 0 */
pushq %rbx /* pt_regs->rbx */
pushq %rbp /* pt_regs->rbp */
pushq %rbp /* pt_regs->rbp (will be overwritten) */
pushq %r8 /* pt_regs->r12 = 0 */
pushq %r8 /* pt_regs->r13 = 0 */
pushq %r8 /* pt_regs->r14 = 0 */