From: Andi Kleen <andi@firstfloor.org>
To: tglx@linutronix.de
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, dwmw@amazon.co.uk, pjt@google.com,
luto@kernel.org, peterz@infradead.org, thomas.lendacky@amd.com,
tim.c.chen@linux.intel.com, gregkh@linux-foundation.org,
dave.hansen@intel.com, jikos@kernel.org,
Andi Kleen <ak@linux.intel.com>
Subject: [PATCH v1 8/8] x86/entry/clearregs: Clear registers for 32bit kernel
Date: Tue, 9 Jan 2018 17:03:28 -0800 [thread overview]
Message-ID: <20180110010328.22163-9-andi@firstfloor.org> (raw)
In-Reply-To: <20180110010328.22163-1-andi@firstfloor.org>
From: Andi Kleen <ak@linux.intel.com>
On a 32bit kernel clearing registers is much simpler than
on 64bit. The arguments for syscalls are initially passed
to a C function through the stack, so there's no need
to figure out how many arguments to clear.
So we always clear all registers (except frame pointer) for
all entry points.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
arch/x86/entry/entry_32.S | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index d2ef7f32905b..aee1085534ac 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -221,6 +221,18 @@
POP_GS_EX
.endm
+.macro CLEAR_ALL_REGS
+#ifdef CONFIG_FRAME_POINTER
+ xorl %ebp, %ebp
+#endif
+ xorl %eax, %eax
+ xorl %ebx, %ebx
+ xorl %ecx, %ecx
+ xorl %edx, %edx
+ xorl %edi, %edi
+ xorl %esi, %esi
+.endm
+
/*
* %eax: prev task
* %edx: next task
@@ -428,6 +440,7 @@ ENTRY(entry_SYSENTER_32)
pushl $0 /* pt_regs->ip = 0 (placeholder) */
pushl %eax /* pt_regs->orig_ax */
SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */
+ CLEAR_ALL_REGS
/*
* SYSENTER doesn't filter flags, so we need to clear NT, AC
@@ -539,6 +552,7 @@ ENTRY(entry_INT80_32)
ASM_CLAC
pushl %eax /* pt_regs->orig_ax */
SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */
+ CLEAR_ALL_REGS
/*
* User mode is traced as though IRQs are on, and the interrupt gate
@@ -673,6 +687,7 @@ common_interrupt:
ASM_CLAC
addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */
SAVE_ALL
+ CLEAR_ALL_REGS
ENCODE_FRAME_POINTER
TRACE_IRQS_OFF
movl %esp, %eax
@@ -685,6 +700,7 @@ ENTRY(name) \
ASM_CLAC; \
pushl $~(nr); \
SAVE_ALL; \
+ CLEAR_ALL_REGS; \
ENCODE_FRAME_POINTER; \
TRACE_IRQS_OFF \
movl %esp, %eax; \
@@ -812,6 +828,7 @@ END(spurious_interrupt_bug)
ENTRY(xen_hypervisor_callback)
pushl $-1 /* orig_ax = -1 => not a system call */
SAVE_ALL
+ CLEAR_ALL_REGS
ENCODE_FRAME_POINTER
TRACE_IRQS_OFF
@@ -867,6 +884,7 @@ ENTRY(xen_failsafe_callback)
jmp iret_exc
5: pushl $-1 /* orig_ax = -1 => not a system call */
SAVE_ALL
+ CLEAR_ALL_REGS
ENCODE_FRAME_POINTER
jmp ret_from_exception
@@ -921,6 +939,7 @@ common_exception:
pushl %edx
pushl %ecx
pushl %ebx
+ CLEAR_ALL_REGS
ENCODE_FRAME_POINTER
cld
movl $(__KERNEL_PERCPU), %ecx
@@ -954,6 +973,7 @@ ENTRY(debug)
ASM_CLAC
pushl $-1 # mark this as an int
SAVE_ALL
+ CLEAR_ALL_REGS
ENCODE_FRAME_POINTER
xorl %edx, %edx # error code 0
movl %esp, %eax # pt_regs pointer
@@ -998,6 +1018,7 @@ ENTRY(nmi)
pushl %eax # pt_regs->orig_ax
SAVE_ALL
+ CLEAR_ALL_REGS
ENCODE_FRAME_POINTER
xorl %edx, %edx # zero error code
movl %esp, %eax # pt_regs pointer
@@ -1038,6 +1059,7 @@ ENTRY(nmi)
.endr
pushl %eax
SAVE_ALL
+ CLEAR_ALL_REGS
ENCODE_FRAME_POINTER
FIXUP_ESPFIX_STACK # %eax == %esp
xorl %edx, %edx # zero error code
@@ -1052,6 +1074,7 @@ ENTRY(int3)
ASM_CLAC
pushl $-1 # mark this as an int
SAVE_ALL
+ CLEAR_ALL_REGS
ENCODE_FRAME_POINTER
TRACE_IRQS_OFF
xorl %edx, %edx # zero error code
--
2.14.3
next prev parent reply other threads:[~2018-01-10 1:05 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-10 1:03 x86/clearregs: Register sanitizing at kernel entry for speculation hygiene Andi Kleen
2018-01-10 1:03 ` [PATCH v1 1/8] x86/entry/clearregs: Remove partial stack frame in fast system call Andi Kleen
2018-01-10 2:46 ` Brian Gerst
2018-01-11 0:16 ` Andi Kleen
2018-01-11 0:54 ` Brian Gerst
2018-01-11 1:02 ` Andi Kleen
2018-01-11 0:55 ` Andy Lutomirski
2018-01-11 1:01 ` Andi Kleen
2018-01-11 1:01 ` Brian Gerst
2018-01-11 1:22 ` Andy Lutomirski
2018-01-11 1:47 ` Andi Kleen
2018-01-11 18:44 ` Andi Kleen
2018-01-11 2:09 ` Josh Poimboeuf
2018-01-12 3:22 ` Josh Poimboeuf
2018-01-10 1:03 ` [PATCH v1 2/8] x86/entry/clearregs: Add infrastructure to clear registers Andi Kleen
2018-01-11 19:58 ` Konrad Rzeszutek Wilk
2018-01-11 20:10 ` Andi Kleen
2018-01-10 1:03 ` [PATCH v1 3/8] x86/entry/clearregs: Clear registers for 64bit SYSCALL Andi Kleen
2018-01-11 3:35 ` Brian Gerst
2018-01-11 18:47 ` Andi Kleen
2018-01-12 3:45 ` Josh Poimboeuf
2018-01-10 1:03 ` [PATCH v1 4/8] x86/entry/retpoline: Clear extra registers for compat syscalls Andi Kleen
2018-01-10 1:03 ` [PATCH v1 5/8] x86/entry/clearregs: Clear registers for 64bit exceptions/interrupts Andi Kleen
2018-01-10 1:23 ` Andy Lutomirski
2018-01-10 1:03 ` [PATCH v1 6/8] x86/entry/clearregs: Add number of arguments to syscall tables Andi Kleen
2018-01-10 1:26 ` Andy Lutomirski
2018-01-10 4:37 ` Andi Kleen
2018-01-10 20:05 ` Andy Lutomirski
2018-01-10 1:03 ` [PATCH v1 7/8] x86/entry/clearregs: Add 64bit stubs to clear unused arguments regs Andi Kleen
2018-01-10 1:03 ` Andi Kleen [this message]
2018-01-10 1:24 ` [PATCH v1 8/8] x86/entry/clearregs: Clear registers for 32bit kernel Andy Lutomirski
2018-01-10 1:16 ` x86/clearregs: Register sanitizing at kernel entry for speculation hygiene Andy Lutomirski
2018-01-10 1:34 ` Andi Kleen
2018-01-10 1:39 ` Andy Lutomirski
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