Commit-ID:  eb47854415825a69b1c578e7487da571227ba25a
Gitweb:     http://git.kernel.org/tip/eb47854415825a69b1c578e7487da571227ba25a
Author:     Denys Vlasenko <dvlas...@redhat.com>
AuthorDate: Sun, 7 Jun 2015 20:24:30 +0200
Committer:  Ingo Molnar <mi...@kernel.org>
CommitDate: Mon, 8 Jun 2015 23:43:37 +0200

x86/asm/entry/32: Reinstate clearing of pt_regs->r8..r11 on EFAULT path

I broke this recently when I changed pt_regs->r8..r11 clearing
logic in INT 80 code path.

There is a branch from SYSENTER/SYSCALL code to INT 80 code:
if we fail to retrieve arg6, we return EFAULT. Before this
patch, in this case we don't clear pt_regs->r8..r11.

This patch fixes this. The resulting code is smaller and
simpler.

While at it, remove incorrect comment about syscall dispatching
CALL insn: it does not use RIP-relative addressing form (the
comment was meant to be "TODO: make this rip-relative", and
morphed since then, dropping "TODO").

Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
Cc: Alexei Starovoitov <a...@plumgrid.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Will Drewry <w...@chromium.org>
Link: 
http://lkml.kernel.org/r/1433701470-28800-1-git-send-email-dvlas...@redhat.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
 arch/x86/entry/entry_64_compat.S | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 59840e3..5757dde 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -413,9 +413,7 @@ END(entry_SYSCALL_compat)
 
 ia32_badarg:
        ASM_CLAC
-       movq    $-EFAULT, %rax
-       jmp     ia32_sysret
-
+       movq    $-EFAULT, RAX(%rsp)
 ia32_ret_from_sys_call:
        xorl    %eax, %eax              /* Do not leak kernel information */
        movq    %rax, R11(%rsp)
@@ -486,9 +484,7 @@ ia32_do_call:
        cmpq    $(IA32_NR_syscalls-1), %rax
        ja      1f
 
-       call    *ia32_sys_call_table(, %rax, 8) /* RIP relative */
-
-ia32_sysret:
+       call    *ia32_sys_call_table(, %rax, 8)
        movq    %rax, RAX(%rsp)
 1:
        jmp     int_ret_from_sys_call
--
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