diff options
| author | Andy Lutomirski | 2015-12-16 23:18:48 -0800 |
|---|---|---|
| committer | Thomas Gleixner | 2015-12-21 16:05:01 +0100 |
| commit | 30bfa7b3488bfb1bb75c9f50a5fcac1832970c60 (patch) | |
| tree | af1e7d3bb55f826b936c7a292b8f0f389b641222 /arch/x86/entry/common.c | |
| parent | 6a613ac6bc015f8ef75806d397d69dbac4a8d8c4 (diff) | |
x86/entry: Restore traditional SYSENTER calling convention
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>
Diffstat (limited to 'arch/x86/entry/common.c')
| -rw-r--r-- | arch/x86/entry/common.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index a89fdbc1f0be..03663740c866 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -421,7 +421,7 @@ __visible long do_fast_syscall_32(struct pt_regs *regs) regs->ip = landing_pad; /* - * Fetch ECX from where the vDSO stashed it. + * Fetch EBP from where the vDSO stashed it. * * WARNING: We are in CONTEXT_USER and RCU isn't paying attention! */ @@ -432,10 +432,10 @@ __visible long do_fast_syscall_32(struct pt_regs *regs) * Micro-optimization: the pointer we're following is explicitly * 32 bits, so it can't be out of range. */ - __get_user(*(u32 *)®s->cx, + __get_user(*(u32 *)®s->bp, (u32 __user __force *)(unsigned long)(u32)regs->sp) #else - get_user(*(u32 *)®s->cx, + get_user(*(u32 *)®s->bp, (u32 __user __force *)(unsigned long)(u32)regs->sp) #endif ) { |