In 32-bit SYSENTER code, load arg6 into R9 instead of EBP.
Jump to SYSCALL code path after we finish setting up pt_regs
and clearing FLAGS_NT.
This leaves most of SYSENTER32 code path inaccessible.
Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
CC: Ingo Molnar <mi...@kernel.org>
CC: Linus Torvalds <torva...@linux-foundation.org>
CC: Krzysztof A. Sobiecki <sob...@gmail.com>
CC: Steven Rostedt <rost...@goodmis.org>
CC: Borislav Petkov <b...@alien8.de>
CC: "H. Peter Anvin" <h...@zytor.com>
CC: Andy Lutomirski <l...@amacapital.net>
CC: Oleg Nesterov <o...@redhat.com>
CC: Frederic Weisbecker <fweis...@gmail.com>
CC: Alexei Starovoitov <a...@plumgrid.com>
CC: Will Drewry <w...@chromium.org>
CC: Kees Cook <keesc...@chromium.org>
CC: x...@kernel.org
CC: linux-kernel@vger.kernel.org
---
arch/x86/entry/entry_64_compat.S | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index df102e8..d74745a 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -93,7 +93,7 @@ ENTRY(entry_SYSENTER_compat)
* 32-bit zero extended
*/
ASM_STAC
-1: movl (%rbp), %ebp
+1: movl (%rbp), %r9d
_ASM_EXTABLE(1b, ia32_badarg)
ASM_CLAC
@@ -105,6 +105,7 @@ ENTRY(entry_SYSENTER_compat)
testl $X86_EFLAGS_NT, EFLAGS(%rsp)
jnz sysenter_fix_flags
sysenter_flags_fixed:
+ jmp sysenter_jumps_here
orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp,
SIZEOF_PTREGS)
@@ -343,6 +344,7 @@ ENTRY(entry_SYSCALL_compat)
_ASM_EXTABLE(1b, ia32_badarg)
ASM_CLAC
+sysenter_jumps_here:
orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp,
SIZEOF_PTREGS)
jnz cstar_tracesys
--
1.8.1.4
--
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