korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-26 21:54:11 +08:00
Code Issues Packages Projects Releases Wiki Activity

x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER

Browse Source 
Move the clearing of the high bits of RAX after Xen PV joins the SYSENTER
path so that Xen PV doesn't skip it.

Arguably this code should be deleted instead, but that would belong in the
merge window.

Fixes: ffae641f57 ("x86/entry/64/compat: Fix Xen PV SYSENTER frame setup")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/9d33b3f3216dcab008070f1c28b6091ae7199969.1593795633.git.luto@kernel.org
This commit is contained in:
Andy Lutomirski 2020-07-03 10:02:53 -07:00 committed by Thomas Gleixner
parent cced0b24bb
commit db5b2c5a90
1 changed files with 10 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
arch/x86/entry/entry_64_compat.S
View File

@ -57,15 +57,6 @@ SYM_CODE_START(entry_SYSENTER_compat)
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
/*
* User tracing code (ptrace or signal handlers) might assume that
* the saved RAX contains a 32-bit number when we're invoking a 32-bit
* syscall. Just in case the high bits are nonzero, zero-extend
* the syscall number. (This could almost certainly be deleted
* with no ill effects.)
*/
movl %eax, %eax
/* Construct struct pt_regs on stack */
pushq $__USER32_DS /* pt_regs->ss */
pushq $0 /* pt_regs->sp = 0 (placeholder) */
@ -80,6 +71,16 @@ SYM_CODE_START(entry_SYSENTER_compat)
pushq $__USER32_CS /* pt_regs->cs */
pushq $0 /* pt_regs->ip = 0 (placeholder) */
SYM_INNER_LABEL(entry_SYSENTER_compat_after_hwframe, SYM_L_GLOBAL)
/*
* User tracing code (ptrace or signal handlers) might assume that
* the saved RAX contains a 32-bit number when we're invoking a 32-bit
* syscall. Just in case the high bits are nonzero, zero-extend
* the syscall number. (This could almost certainly be deleted
* with no ill effects.)
*/
movl %eax, %eax
pushq %rax /* pt_regs->orig_ax */
pushq %rdi /* pt_regs->di */
pushq %rsi /* pt_regs->si */