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

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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 <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433701470-28800-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Denys Vlasenko 2015-06-07 20:24:30 +02:00 committed by Ingo Molnar
parent 4d7321381e
commit eb47854415
1 changed files with 2 additions and 6 deletions
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8
arch/x86/entry/entry_64_compat.S
View file

@ -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