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 <[email protected]>
---
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
Commit-ID: f19a25c872b20ae4357f72687cf3e7b0da220ee2
Gitweb: http://git.kernel.org/tip/f19a25c872b20ae4357f72687cf3e7b0da220ee2
Author: Brian Gerst <[email protected]>
AuthorDate: Mon, 25 Jan 2010 10:47:33 -0500
Committer: H. Peter Anvin <[email protected]>
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 <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: H. Peter Anvin <[email protected]>
---
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.
* tip-bot for Brian Gerst <[email protected]> wrote:
> Commit-ID: f19a25c872b20ae4357f72687cf3e7b0da220ee2
> Gitweb: http://git.kernel.org/tip/f19a25c872b20ae4357f72687cf3e7b0da220ee2
> Author: Brian Gerst <[email protected]>
> AuthorDate: Mon, 25 Jan 2010 10:47:33 -0500
> Committer: H. Peter Anvin <[email protected]>
> 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 <[email protected]>
> LKML-Reference: <[email protected]>
> Signed-off-by: H. Peter Anvin <[email protected]>
> ---
> 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
On Wed, Jan 27, 2010 at 8:07 AM, Ingo Molnar <[email protected]> wrote:
>
> * tip-bot for Brian Gerst <[email protected]> wrote:
>
>> Commit-ID: f19a25c872b20ae4357f72687cf3e7b0da220ee2
>> Gitweb: http://git.kernel.org/tip/f19a25c872b20ae4357f72687cf3e7b0da220ee2
>> Author: Brian Gerst <[email protected]>
>> AuthorDate: Mon, 25 Jan 2010 10:47:33 -0500
>> Committer: H. Peter Anvin <[email protected]>
>> 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 <[email protected]>
>> LKML-Reference: <[email protected]>
>> Signed-off-by: H. Peter Anvin <[email protected]>
>> ---
>> 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
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.