* [PATCH] x86-64: Use normal ptregs stub for execve
@ 2010-01-25 15:47 Brian Gerst
2010-01-27 8:39 ` [tip:x86/asm] " tip-bot for Brian Gerst
0 siblings, 1 reply; 5+ messages in thread
From: Brian Gerst @ 2010-01-25 15:47 UTC (permalink / raw)
To: hpa; +Cc: x86, linux-kernel
Execve historically passed regs by value, so it had a seperate stub.
This is no longer true, so change it to use a normal PTREGSCALL stub.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
arch/x86/kernel/entry_64.S | 17 +----------------
1 files changed, 1 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 0697ff1..0c31502 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -696,6 +696,7 @@ END(\label)
PTREGSCALL stub_clone, sys_clone, %r8
PTREGSCALL stub_fork, sys_fork, %rdi
PTREGSCALL stub_vfork, sys_vfork, %rdi
+ PTREGSCALL stub_execve, sys_execve, %rcx
PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
PTREGSCALL stub_iopl, sys_iopl, %rsi
@@ -712,22 +713,6 @@ ENTRY(ptregscall_common)
CFI_ENDPROC
END(ptregscall_common)
-ENTRY(stub_execve)
- CFI_STARTPROC
- popq %r11
- CFI_ADJUST_CFA_OFFSET -8
- CFI_REGISTER rip, r11
- SAVE_REST
- FIXUP_TOP_OF_STACK %r11
- movq %rsp, %rcx
- call sys_execve
- RESTORE_TOP_OF_STACK %r11
- movq %rax,RAX(%rsp)
- RESTORE_REST
- jmp int_ret_from_sys_call
- CFI_ENDPROC
-END(stub_execve)
-
/*
* sigreturn is special because it needs to restore all registers on return.
* This cannot be done with SYSRET, so use the IRET return path instead.
--
1.6.6
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [tip:x86/asm] x86-64: Use normal ptregs stub for execve
2010-01-25 15:47 [PATCH] x86-64: Use normal ptregs stub for execve Brian Gerst
@ 2010-01-27 8:39 ` tip-bot for Brian Gerst
2010-01-27 13:07 ` Ingo Molnar
0 siblings, 1 reply; 5+ messages in thread
From: tip-bot for Brian Gerst @ 2010-01-27 8:39 UTC (permalink / raw)
To: linux-tip-commits; +Cc: linux-kernel, hpa, mingo, brgerst, tglx
Commit-ID: f19a25c872b20ae4357f72687cf3e7b0da220ee2
Gitweb: http://git.kernel.org/tip/f19a25c872b20ae4357f72687cf3e7b0da220ee2
Author: Brian Gerst <brgerst@gmail.com>
AuthorDate: Mon, 25 Jan 2010 10:47:33 -0500
Committer: H. Peter Anvin <hpa@zytor.com>
CommitDate: Tue, 26 Jan 2010 23:38:14 -0800
x86-64: Use normal ptregs stub for execve
Execve historically passed regs by value, so it had a seperate stub.
This is no longer true, so change it to use a normal PTREGSCALL stub.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1264434453-2204-1-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
arch/x86/kernel/entry_64.S | 17 +----------------
1 files changed, 1 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 0697ff1..0c31502 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -696,6 +696,7 @@ END(\label)
PTREGSCALL stub_clone, sys_clone, %r8
PTREGSCALL stub_fork, sys_fork, %rdi
PTREGSCALL stub_vfork, sys_vfork, %rdi
+ PTREGSCALL stub_execve, sys_execve, %rcx
PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
PTREGSCALL stub_iopl, sys_iopl, %rsi
@@ -712,22 +713,6 @@ ENTRY(ptregscall_common)
CFI_ENDPROC
END(ptregscall_common)
-ENTRY(stub_execve)
- CFI_STARTPROC
- popq %r11
- CFI_ADJUST_CFA_OFFSET -8
- CFI_REGISTER rip, r11
- SAVE_REST
- FIXUP_TOP_OF_STACK %r11
- movq %rsp, %rcx
- call sys_execve
- RESTORE_TOP_OF_STACK %r11
- movq %rax,RAX(%rsp)
- RESTORE_REST
- jmp int_ret_from_sys_call
- CFI_ENDPROC
-END(stub_execve)
-
/*
* sigreturn is special because it needs to restore all registers on return.
* This cannot be done with SYSRET, so use the IRET return path instead.
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [tip:x86/asm] x86-64: Use normal ptregs stub for execve
2010-01-27 8:39 ` [tip:x86/asm] " tip-bot for Brian Gerst
@ 2010-01-27 13:07 ` Ingo Molnar
2010-01-27 15:21 ` Brian Gerst
0 siblings, 1 reply; 5+ messages in thread
From: Ingo Molnar @ 2010-01-27 13:07 UTC (permalink / raw)
To: mingo, hpa, linux-kernel, brgerst, tglx; +Cc: linux-tip-commits
* tip-bot for Brian Gerst <brgerst@gmail.com> wrote:
> Commit-ID: f19a25c872b20ae4357f72687cf3e7b0da220ee2
> Gitweb: http://git.kernel.org/tip/f19a25c872b20ae4357f72687cf3e7b0da220ee2
> Author: Brian Gerst <brgerst@gmail.com>
> AuthorDate: Mon, 25 Jan 2010 10:47:33 -0500
> Committer: H. Peter Anvin <hpa@zytor.com>
> CommitDate: Tue, 26 Jan 2010 23:38:14 -0800
>
> x86-64: Use normal ptregs stub for execve
>
> Execve historically passed regs by value, so it had a seperate stub.
> This is no longer true, so change it to use a normal PTREGSCALL stub.
>
> Signed-off-by: Brian Gerst <brgerst@gmail.com>
> LKML-Reference: <1264434453-2204-1-git-send-email-brgerst@gmail.com>
> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
> ---
> arch/x86/kernel/entry_64.S | 17 +----------------
> 1 files changed, 1 insertions(+), 16 deletions(-)
FYI, -tip testing found that this commit breaks the grub binary on 64-bit,
simply running /sbin/grub causes it to segfault:
[ 3145.999766] grub[6706] general protection ip:805c481 sp:ff95629c error:0 in
grub[8048000+8c000]
i've excluded this commit for now.
Ingo
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [tip:x86/asm] x86-64: Use normal ptregs stub for execve
2010-01-27 13:07 ` Ingo Molnar
@ 2010-01-27 15:21 ` Brian Gerst
2010-01-27 16:28 ` H. Peter Anvin
0 siblings, 1 reply; 5+ messages in thread
From: Brian Gerst @ 2010-01-27 15:21 UTC (permalink / raw)
To: Ingo Molnar; +Cc: mingo, hpa, linux-kernel, tglx, linux-tip-commits
On Wed, Jan 27, 2010 at 8:07 AM, Ingo Molnar <mingo@elte.hu> wrote:
>
> * tip-bot for Brian Gerst <brgerst@gmail.com> wrote:
>
>> Commit-ID: f19a25c872b20ae4357f72687cf3e7b0da220ee2
>> Gitweb: http://git.kernel.org/tip/f19a25c872b20ae4357f72687cf3e7b0da220ee2
>> Author: Brian Gerst <brgerst@gmail.com>
>> AuthorDate: Mon, 25 Jan 2010 10:47:33 -0500
>> Committer: H. Peter Anvin <hpa@zytor.com>
>> CommitDate: Tue, 26 Jan 2010 23:38:14 -0800
>>
>> x86-64: Use normal ptregs stub for execve
>>
>> Execve historically passed regs by value, so it had a seperate stub.
>> This is no longer true, so change it to use a normal PTREGSCALL stub.
>>
>> Signed-off-by: Brian Gerst <brgerst@gmail.com>
>> LKML-Reference: <1264434453-2204-1-git-send-email-brgerst@gmail.com>
>> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
>> ---
>> arch/x86/kernel/entry_64.S | 17 +----------------
>> 1 files changed, 1 insertions(+), 16 deletions(-)
>
> FYI, -tip testing found that this commit breaks the grub binary on 64-bit,
> simply running /sbin/grub causes it to segfault:
>
> [ 3145.999766] grub[6706] general protection ip:805c481 sp:ff95629c error:0 in
> grub[8048000+8c000]
>
> i've excluded this commit for now.
>
> Ingo
>
>
I see what is going on. Grub is a 32-bit statically linked executable
even on a 64-bit distro. The old execve stub forced return to
userspace via iret, but PTREGSCALL apparently doesn't. This means
that the 32-bit %cs isn't getting set. Drop this patch for now.
--
Brian Gerst
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [tip:x86/asm] x86-64: Use normal ptregs stub for execve
2010-01-27 15:21 ` Brian Gerst
@ 2010-01-27 16:28 ` H. Peter Anvin
0 siblings, 0 replies; 5+ messages in thread
From: H. Peter Anvin @ 2010-01-27 16:28 UTC (permalink / raw)
To: Brian Gerst; +Cc: Ingo Molnar, mingo, linux-kernel, tglx, linux-tip-commits
On 01/27/2010 07:21 AM, Brian Gerst wrote:
>
> I see what is going on. Grub is a 32-bit statically linked executable
> even on a 64-bit distro. The old execve stub forced return to
> userspace via iret, but PTREGSCALL apparently doesn't. This means
> that the 32-bit %cs isn't getting set. Drop this patch for now.
>
OK, I presume that breaks execing any 32-bit app, not just statically
linked (eww...)
Yet one more case of Grub making me shudder, though :-/
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2010-01-25 15:47 [PATCH] x86-64: Use normal ptregs stub for execve Brian Gerst
2010-01-27 8:39 ` [tip:x86/asm] " tip-bot for Brian Gerst
2010-01-27 13:07 ` Ingo Molnar
2010-01-27 15:21 ` Brian Gerst
2010-01-27 16:28 ` H. Peter Anvin
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