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Subject[PATCH] 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 <>
CC: Linus Torvalds <>
CC: Steven Rostedt <>
CC: Ingo Molnar <>
CC: Borislav Petkov <>
CC: "H. Peter Anvin" <>
CC: Andy Lutomirski <>
CC: Oleg Nesterov <>
CC: Frederic Weisbecker <>
CC: Alexei Starovoitov <>
CC: Will Drewry <>
CC: Kees Cook <>
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 9558dac..b80f8d4 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -413,9 +413,7 @@ END(ia32_cstar_target)

- movq $-EFAULT, %rax
- jmp ia32_sysret
+ movq $-EFAULT, RAX(%rsp)
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 */
+ call *ia32_sys_call_table(, %rax, 8)
movq %rax, RAX(%rsp)
jmp int_ret_from_sys_call

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