* [PATCH] x86/entry/32: pass cr2 to do_async_page_fault
@ 2019-07-24 4:20 Matt Mullins
2019-07-24 9:14 ` Peter Zijlstra
2019-07-24 10:22 ` [tip:x86/urgent] x86/entry/32: Pass cr2 to do_async_page_fault() tip-bot for Matt Mullins
0 siblings, 2 replies; 3+ messages in thread
From: Matt Mullins @ 2019-07-24 4:20 UTC (permalink / raw)
To: peterz, tglx, luto
Cc: Matt Mullins, Ingo Molnar, Borislav Petkov, H. Peter Anvin, x86,
linux-kernel
Commit a0d14b8909de ("x86/mm, tracing: Fix CR2 corruption") added the
address parameter to do_async_page_fault, but does not pass it from the
32-bit entry point. To plumb it through, factor-out
common_exception_read_cr2 in the same fashion as common_exception, and
uses it from both page_fault and async_page_fault.
For a 32-bit KVM guest, this fixes:
[ 1.148669][ T1] Run /sbin/init as init process
[ 1.153328][ T1] Starting init: /sbin/init exists but couldn't execute it (error -14)
Fixes: a0d14b8909de ("x86/mm, tracing: Fix CR2 corruption")
Signed-off-by: Matt Mullins <mmullins@fb.com>
---
arch/x86/entry/entry_32.S | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 2bb986f305ac..4f86928246e7 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -1443,8 +1443,12 @@ BUILD_INTERRUPT3(hv_stimer0_callback_vector, HYPERV_STIMER0_VECTOR,
ENTRY(page_fault)
ASM_CLAC
- pushl $0; /* %gs's slot on the stack */
+ pushl $do_page_fault
+ jmp common_exception_read_cr2
+END(page_fault)
+common_exception_read_cr2:
+ /* the function address is in %gs's slot on the stack */
SAVE_ALL switch_stacks=1 skip_gs=1
ENCODE_FRAME_POINTER
@@ -1452,6 +1456,7 @@ ENTRY(page_fault)
/* fixup %gs */
GS_TO_REG %ecx
+ movl PT_GS(%esp), %edi
REG_TO_PTGS %ecx
SET_KERNEL_GS %ecx
@@ -1463,9 +1468,9 @@ ENTRY(page_fault)
TRACE_IRQS_OFF
movl %esp, %eax # pt_regs pointer
- call do_page_fault
+ CALL_NOSPEC %edi
jmp ret_from_exception
-END(page_fault)
+END(common_exception_read_cr2)
common_exception:
/* the function address is in %gs's slot on the stack */
@@ -1595,7 +1600,7 @@ END(general_protection)
ENTRY(async_page_fault)
ASM_CLAC
pushl $do_async_page_fault
- jmp common_exception
+ jmp common_exception_read_cr2
END(async_page_fault)
#endif
--
2.17.1
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] x86/entry/32: pass cr2 to do_async_page_fault
2019-07-24 4:20 [PATCH] x86/entry/32: pass cr2 to do_async_page_fault Matt Mullins
@ 2019-07-24 9:14 ` Peter Zijlstra
2019-07-24 10:22 ` [tip:x86/urgent] x86/entry/32: Pass cr2 to do_async_page_fault() tip-bot for Matt Mullins
1 sibling, 0 replies; 3+ messages in thread
From: Peter Zijlstra @ 2019-07-24 9:14 UTC (permalink / raw)
To: Matt Mullins
Cc: tglx, luto, Ingo Molnar, Borislav Petkov, H. Peter Anvin, x86,
linux-kernel
On Tue, Jul 23, 2019 at 09:20:58PM -0700, Matt Mullins wrote:
> Commit a0d14b8909de ("x86/mm, tracing: Fix CR2 corruption") added the
> address parameter to do_async_page_fault, but does not pass it from the
> 32-bit entry point. To plumb it through, factor-out
> common_exception_read_cr2 in the same fashion as common_exception, and
> uses it from both page_fault and async_page_fault.
>
> For a 32-bit KVM guest, this fixes:
>
> [ 1.148669][ T1] Run /sbin/init as init process
> [ 1.153328][ T1] Starting init: /sbin/init exists but couldn't execute it (error -14)
>
> Fixes: a0d14b8909de ("x86/mm, tracing: Fix CR2 corruption")
> Signed-off-by: Matt Mullins <mmullins@fb.com>
Argh. Sorry for overlooking that one.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
There's some potential for sharing between common_exception and your
common_exception_read_cr2, I'll see if I can do that without making a
mess of it.
Also; FB uses 32bit guests?!?
> ---
> arch/x86/entry/entry_32.S | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
> index 2bb986f305ac..4f86928246e7 100644
> --- a/arch/x86/entry/entry_32.S
> +++ b/arch/x86/entry/entry_32.S
> @@ -1443,8 +1443,12 @@ BUILD_INTERRUPT3(hv_stimer0_callback_vector, HYPERV_STIMER0_VECTOR,
>
> ENTRY(page_fault)
> ASM_CLAC
> - pushl $0; /* %gs's slot on the stack */
> + pushl $do_page_fault
> + jmp common_exception_read_cr2
> +END(page_fault)
>
> +common_exception_read_cr2:
> + /* the function address is in %gs's slot on the stack */
> SAVE_ALL switch_stacks=1 skip_gs=1
>
> ENCODE_FRAME_POINTER
> @@ -1452,6 +1456,7 @@ ENTRY(page_fault)
>
> /* fixup %gs */
> GS_TO_REG %ecx
> + movl PT_GS(%esp), %edi
> REG_TO_PTGS %ecx
> SET_KERNEL_GS %ecx
>
> @@ -1463,9 +1468,9 @@ ENTRY(page_fault)
>
> TRACE_IRQS_OFF
> movl %esp, %eax # pt_regs pointer
> - call do_page_fault
> + CALL_NOSPEC %edi
> jmp ret_from_exception
> -END(page_fault)
> +END(common_exception_read_cr2)
>
> common_exception:
> /* the function address is in %gs's slot on the stack */
> @@ -1595,7 +1600,7 @@ END(general_protection)
> ENTRY(async_page_fault)
> ASM_CLAC
> pushl $do_async_page_fault
> - jmp common_exception
> + jmp common_exception_read_cr2
> END(async_page_fault)
> #endif
>
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread* [tip:x86/urgent] x86/entry/32: Pass cr2 to do_async_page_fault()
2019-07-24 4:20 [PATCH] x86/entry/32: pass cr2 to do_async_page_fault Matt Mullins
2019-07-24 9:14 ` Peter Zijlstra
@ 2019-07-24 10:22 ` tip-bot for Matt Mullins
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Matt Mullins @ 2019-07-24 10:22 UTC (permalink / raw)
To: linux-tip-commits; +Cc: mmullins, mingo, peterz, hpa, tglx, linux-kernel
Commit-ID: b8f70953c1251d8b16276995816a95639f598e70
Gitweb: https://git.kernel.org/tip/b8f70953c1251d8b16276995816a95639f598e70
Author: Matt Mullins <mmullins@fb.com>
AuthorDate: Tue, 23 Jul 2019 21:20:58 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 24 Jul 2019 12:17:39 +0200
x86/entry/32: Pass cr2 to do_async_page_fault()
Commit a0d14b8909de ("x86/mm, tracing: Fix CR2 corruption") added the
address parameter to do_async_page_fault(), but does not pass it from the
32-bit entry point. To plumb it through, factor-out
common_exception_read_cr2 in the same fashion as common_exception, and uses
it from both page_fault and async_page_fault.
For a 32-bit KVM guest, this fixes:
Run /sbin/init as init process
Starting init: /sbin/init exists but couldn't execute it (error -14)
Fixes: a0d14b8909de ("x86/mm, tracing: Fix CR2 corruption")
Signed-off-by: Matt Mullins <mmullins@fb.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190724042058.24506-1-mmullins@fb.com
---
arch/x86/entry/entry_32.S | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 2bb986f305ac..4f86928246e7 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -1443,8 +1443,12 @@ BUILD_INTERRUPT3(hv_stimer0_callback_vector, HYPERV_STIMER0_VECTOR,
ENTRY(page_fault)
ASM_CLAC
- pushl $0; /* %gs's slot on the stack */
+ pushl $do_page_fault
+ jmp common_exception_read_cr2
+END(page_fault)
+common_exception_read_cr2:
+ /* the function address is in %gs's slot on the stack */
SAVE_ALL switch_stacks=1 skip_gs=1
ENCODE_FRAME_POINTER
@@ -1452,6 +1456,7 @@ ENTRY(page_fault)
/* fixup %gs */
GS_TO_REG %ecx
+ movl PT_GS(%esp), %edi
REG_TO_PTGS %ecx
SET_KERNEL_GS %ecx
@@ -1463,9 +1468,9 @@ ENTRY(page_fault)
TRACE_IRQS_OFF
movl %esp, %eax # pt_regs pointer
- call do_page_fault
+ CALL_NOSPEC %edi
jmp ret_from_exception
-END(page_fault)
+END(common_exception_read_cr2)
common_exception:
/* the function address is in %gs's slot on the stack */
@@ -1595,7 +1600,7 @@ END(general_protection)
ENTRY(async_page_fault)
ASM_CLAC
pushl $do_async_page_fault
- jmp common_exception
+ jmp common_exception_read_cr2
END(async_page_fault)
#endif
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-07-24 4:20 [PATCH] x86/entry/32: pass cr2 to do_async_page_fault Matt Mullins
2019-07-24 9:14 ` Peter Zijlstra
2019-07-24 10:22 ` [tip:x86/urgent] x86/entry/32: Pass cr2 to do_async_page_fault() tip-bot for Matt Mullins
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