Hi all,
After merging the tip tree, today's linux-next build (x86_64 allmodconfig)
failed like this:
In file included from tools/arch/x86/include/asm/nops.h:5,
from arch/x86/decode.c:15:
tools/arch/x86/include/asm/asm.h:185:24: error: invalid register name for 'current_stack_pointer'
185 | register unsigned long current_stack_pointer asm(_ASM_SP);
| ^~~~~~~~~~~~~~~~~~~~~
Caused by commit
eef23e72b78b ("x86/asm: Use _ASM_BYTES() in <asm/nops.h>")
I have used the tip tree from next-20210512 for today.
--
Cheers,
Stephen Rothwell
* Stephen Rothwell <[email protected]> wrote:
> Hi all,
>
> After merging the tip tree, today's linux-next build (x86_64 allmodconfig)
> failed like this:
>
> In file included from tools/arch/x86/include/asm/nops.h:5,
> from arch/x86/decode.c:15:
> tools/arch/x86/include/asm/asm.h:185:24: error: invalid register name for 'current_stack_pointer'
> 185 | register unsigned long current_stack_pointer asm(_ASM_SP);
> | ^~~~~~~~~~~~~~~~~~~~~
>
> Caused by commit
>
> eef23e72b78b ("x86/asm: Use _ASM_BYTES() in <asm/nops.h>")
>
> I have used the tip tree from next-20210512 for today.
Hm, this must be some cross-build artifact or toolchain version dependency
- as plain native build of x86-64 allmodconfig builds just fine:
CC arch/x86/decode.o
LD arch/x86/objtool-in.o
I tried with gcc-8, but that didn't trigger it.
I suppose the workaround below would make it build - but that's not a real
solution.
hpa, any ideas?
Thanks,
Ingo
diff --git a/tools/arch/x86/include/asm/asm.h b/tools/arch/x86/include/asm/asm.h
index 507a37a46027..ada5482c024a 100644
--- a/tools/arch/x86/include/asm/asm.h
+++ b/tools/arch/x86/include/asm/asm.h
@@ -176,14 +176,6 @@
/* For C file, we already have NOKPROBE_SYMBOL macro */
-/*
- * This output constraint should be used for any inline asm which has a "call"
- * instruction. Otherwise the asm may be inserted before the frame pointer
- * gets set up by the containing function. If you forget to do this, objtool
- * may print a "call without frame pointer save/setup" warning.
- */
-register unsigned long current_stack_pointer asm(_ASM_SP);
-#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_ASM_H */
Needed some head scratching, but then...
It makes sense for the cross-build: it's building for the host, and a non-x86 machine isn't doing to have a register named "%rsp".
So this needs to be protected from non-kernel use either via __KERNEL__ or by factoring the basic macros out into a separate file.
Incidentally, we seem to have three categories of include files now: kernel-only, uapi, and "tools api". Perhaps we need such a "tapi" directory instead of copying things around... the infrastructure for uapi with make headers_install etc ought to be generalizable.
On May 13, 2021 3:51:47 AM PDT, Ingo Molnar <[email protected]> wrote:
>
>* Stephen Rothwell <[email protected]> wrote:
>
>> Hi all,
>>
>> After merging the tip tree, today's linux-next build (x86_64
>allmodconfig)
>> failed like this:
>>
>> In file included from tools/arch/x86/include/asm/nops.h:5,
>> from arch/x86/decode.c:15:
>> tools/arch/x86/include/asm/asm.h:185:24: error: invalid register name
>for 'current_stack_pointer'
>> 185 | register unsigned long current_stack_pointer asm(_ASM_SP);
>> | ^~~~~~~~~~~~~~~~~~~~~
>>
>> Caused by commit
>>
>> eef23e72b78b ("x86/asm: Use _ASM_BYTES() in <asm/nops.h>")
>>
>> I have used the tip tree from next-20210512 for today.
>
>Hm, this must be some cross-build artifact or toolchain version
>dependency
>- as plain native build of x86-64 allmodconfig builds just fine:
>
> CC arch/x86/decode.o
> LD arch/x86/objtool-in.o
>
>I tried with gcc-8, but that didn't trigger it.
>
>I suppose the workaround below would make it build - but that's not a
>real
>solution.
>
>hpa, any ideas?
>
>Thanks,
>
> Ingo
>
>diff --git a/tools/arch/x86/include/asm/asm.h
>b/tools/arch/x86/include/asm/asm.h
>index 507a37a46027..ada5482c024a 100644
>--- a/tools/arch/x86/include/asm/asm.h
>+++ b/tools/arch/x86/include/asm/asm.h
>@@ -176,14 +176,6 @@
>
> /* For C file, we already have NOKPROBE_SYMBOL macro */
>
>-/*
>- * This output constraint should be used for any inline asm which has
>a "call"
>- * instruction. Otherwise the asm may be inserted before the frame
>pointer
>- * gets set up by the containing function. If you forget to do this,
>objtool
>- * may print a "call without frame pointer save/setup" warning.
>- */
>-register unsigned long current_stack_pointer asm(_ASM_SP);
>-#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_X86_ASM_H */
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
* H. Peter Anvin <[email protected]> wrote:
> Needed some head scratching, but then...
>
> It makes sense for the cross-build: it's building for the host, and a
> non-x86 machine isn't doing to have a register named "%rsp".
Oh, indeed, sfr is building on powerpc64 I think?
> So this needs to be protected from non-kernel use either via __KERNEL__
> or by factoring the basic macros out into a separate file.
So something like the below?
The exception table stuff is definitely kernel-only. The others could, in
principle, be used by tooling as well.
Thanks,
Ingo
=======================>
From: Ingo Molnar <[email protected]>
Date: Thu, 13 May 2021 13:41:41 +0200
Subject: [PATCH] x86/asm: Make <asm/asm.h> valid on cross-builds as well
Stephen Rothwell reported that the objtool cross-build breaks on
non-x86 hosts:
> tools/arch/x86/include/asm/asm.h:185:24: error: invalid register name for 'current_stack_pointer'
> 185 | register unsigned long current_stack_pointer asm(_ASM_SP);
> | ^~~~~~~~~~~~~~~~~~~~~
The PowerPC host obviously doesn't know much about x86 register names.
Protect the kernel-specific bits of <asm/asm.h>, so that it can be
included by tooling and cross-built.
Reported-by: Stephen Rothwell <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/include/asm/asm.h | 4 ++++
tools/arch/x86/include/asm/asm.h | 4 ++++
2 files changed, 8 insertions(+)
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 507a37a46027..3ad3da9a7d97 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -120,6 +120,8 @@
# define CC_OUT(c) [_cc_ ## c] "=qm"
#endif
+#ifdef __KERNEL__
+
/* Exception table entry */
#ifdef __ASSEMBLY__
# define _ASM_EXTABLE_HANDLE(from, to, handler) \
@@ -186,4 +188,6 @@ register unsigned long current_stack_pointer asm(_ASM_SP);
#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
#endif /* __ASSEMBLY__ */
+#endif /* __KERNEL__ */
+
#endif /* _ASM_X86_ASM_H */
diff --git a/tools/arch/x86/include/asm/asm.h b/tools/arch/x86/include/asm/asm.h
index 507a37a46027..3ad3da9a7d97 100644
--- a/tools/arch/x86/include/asm/asm.h
+++ b/tools/arch/x86/include/asm/asm.h
@@ -120,6 +120,8 @@
# define CC_OUT(c) [_cc_ ## c] "=qm"
#endif
+#ifdef __KERNEL__
+
/* Exception table entry */
#ifdef __ASSEMBLY__
# define _ASM_EXTABLE_HANDLE(from, to, handler) \
@@ -186,4 +188,6 @@ register unsigned long current_stack_pointer asm(_ASM_SP);
#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
#endif /* __ASSEMBLY__ */
+#endif /* __KERNEL__ */
+
#endif /* _ASM_X86_ASM_H */