[PATCH 4.19 ONLY v4] arm64: vdso: remove commas between macro name and arguments

[PATCH 4.19 ONLY v4] arm64: vdso: remove commas between macro name and arguments

[Jian Cai]

LLVM's integrated assembler appears to assume an argument with default
value is passed whenever it sees a comma right after the macro name.
It will be fine if the number of following arguments is one less than
the number of parameters specified in the macro definition. Otherwise,
it fails. For example, the following code works:

$ cat foo.s
.macro  foo arg1=2, arg2=4
        ldr r0, [r1, #\arg1]
        ldr r0, [r1, #\arg2]
.endm

foo, arg2=8

$ llvm-mc -triple=armv7a -filetype=obj foo.s -o ias.o
arm-linux-gnueabihf-objdump -dr ias.o

ias.o:     file format elf32-littlearm

Disassembly of section .text:

00000000 <.text>:
   0: e5910001 ldr r0, [r1, #2]
   4: e5910003 ldr r0, [r1, #8]

While the the following code would fail:

$ cat foo.s
.macro  foo arg1=2, arg2=4
        ldr r0, [r1, #\arg1]
        ldr r0, [r1, #\arg2]
.endm

foo, arg1=2, arg2=8

$ llvm-mc -triple=armv7a -filetype=obj foo.s -o ias.o
foo.s:6:14: error: too many positional arguments
foo, arg1=2, arg2=8

This causes build failures as follows:

arch/arm64/kernel/vdso/gettimeofday.S:230:24: error: too many positional
arguments
 clock_gettime_return, shift=1
                       ^
arch/arm64/kernel/vdso/gettimeofday.S:253:24: error: too many positional
arguments
 clock_gettime_return, shift=1
                       ^
arch/arm64/kernel/vdso/gettimeofday.S:274:24: error: too many positional
arguments
 clock_gettime_return, shift=1

This error is not in mainline because commit 28b1a824a4f4 ("arm64: vdso:
Substitute gettimeofday() with C implementation") rewrote this assembler
file in C as part of a 25 patch series that is unsuitable for stable.
Just remove the comma in the clock_gettime_return invocations in 4.19 so
that GNU as and LLVM's integrated assembler work the same.

Link:
https://github.com/ClangBuiltLinux/linux/issues/1349

Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Jian Cai <jiancai@google.com>
---
Changes v1 -> v2:
  Keep the comma in the macro definition to be consistent with other
  definitions.

Changes v2 -> v3:
  Edit tags.

Changes v3 -> v4:
  Update the commit message based on Nathan's comments.

 arch/arm64/kernel/vdso/gettimeofday.S | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
index 856fee6d3512..b6faf8b5d1fe 100644
--- a/arch/arm64/kernel/vdso/gettimeofday.S
+++ b/arch/arm64/kernel/vdso/gettimeofday.S
@@ -227,7 +227,7 @@ realtime:
 	seqcnt_check fail=realtime
 	get_ts_realtime res_sec=x10, res_nsec=x11, \
 		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
-	clock_gettime_return, shift=1
+	clock_gettime_return shift=1
 
 	ALIGN
 monotonic:
@@ -250,7 +250,7 @@ monotonic:
 		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
 
 	add_ts sec=x10, nsec=x11, ts_sec=x3, ts_nsec=x4, nsec_to_sec=x9
-	clock_gettime_return, shift=1
+	clock_gettime_return shift=1
 
 	ALIGN
 monotonic_raw:
@@ -271,7 +271,7 @@ monotonic_raw:
 		clock_nsec=x15, nsec_to_sec=x9
 
 	add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
-	clock_gettime_return, shift=1
+	clock_gettime_return shift=1
 
 	ALIGN
 realtime_coarse:
-- 
2.31.1.607.g51e8a6a459-goog

Re: [PATCH 4.19 ONLY v4] arm64: vdso: remove commas between macro name and arguments

[Nathan Chancellor]

On 5/5/2021 6:25 PM, Jian Cai wrote:
> LLVM's integrated assembler appears to assume an argument with default
> value is passed whenever it sees a comma right after the macro name.
> It will be fine if the number of following arguments is one less than
> the number of parameters specified in the macro definition. Otherwise,
> it fails. For example, the following code works:
> 
> $ cat foo.s
> .macro  foo arg1=2, arg2=4
>          ldr r0, [r1, #\arg1]
>          ldr r0, [r1, #\arg2]
> .endm
> 
> foo, arg2=8
> 
> $ llvm-mc -triple=armv7a -filetype=obj foo.s -o ias.o
> arm-linux-gnueabihf-objdump -dr ias.o
> 
> ias.o:     file format elf32-littlearm
> 
> Disassembly of section .text:
> 
> 00000000 <.text>:
>     0: e5910001 ldr r0, [r1, #2]
>     4: e5910003 ldr r0, [r1, #8]
> 
> While the the following code would fail:
> 
> $ cat foo.s
> .macro  foo arg1=2, arg2=4
>          ldr r0, [r1, #\arg1]
>          ldr r0, [r1, #\arg2]
> .endm
> 
> foo, arg1=2, arg2=8
> 
> $ llvm-mc -triple=armv7a -filetype=obj foo.s -o ias.o
> foo.s:6:14: error: too many positional arguments
> foo, arg1=2, arg2=8
> 
> This causes build failures as follows:
> 
> arch/arm64/kernel/vdso/gettimeofday.S:230:24: error: too many positional
> arguments
>   clock_gettime_return, shift=1
>                         ^
> arch/arm64/kernel/vdso/gettimeofday.S:253:24: error: too many positional
> arguments
>   clock_gettime_return, shift=1
>                         ^
> arch/arm64/kernel/vdso/gettimeofday.S:274:24: error: too many positional
> arguments
>   clock_gettime_return, shift=1
> 
> This error is not in mainline because commit 28b1a824a4f4 ("arm64: vdso:
> Substitute gettimeofday() with C implementation") rewrote this assembler
> file in C as part of a 25 patch series that is unsuitable for stable.
> Just remove the comma in the clock_gettime_return invocations in 4.19 so
> that GNU as and LLVM's integrated assembler work the same.
> 
> Link:
> https://github.com/ClangBuiltLinux/linux/issues/1349
> 
> Suggested-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Jian Cai <jiancai@google.com>

Thanks for the updated example and explanation, this looks good to me now.

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
> Changes v1 -> v2:
>    Keep the comma in the macro definition to be consistent with other
>    definitions.
> 
> Changes v2 -> v3:
>    Edit tags.
> 
> Changes v3 -> v4:
>    Update the commit message based on Nathan's comments.
> 
>   arch/arm64/kernel/vdso/gettimeofday.S | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
> index 856fee6d3512..b6faf8b5d1fe 100644
> --- a/arch/arm64/kernel/vdso/gettimeofday.S
> +++ b/arch/arm64/kernel/vdso/gettimeofday.S
> @@ -227,7 +227,7 @@ realtime:
>   	seqcnt_check fail=realtime
>   	get_ts_realtime res_sec=x10, res_nsec=x11, \
>   		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
> -	clock_gettime_return, shift=1
> +	clock_gettime_return shift=1
>   
>   	ALIGN
>   monotonic:
> @@ -250,7 +250,7 @@ monotonic:
>   		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
>   
>   	add_ts sec=x10, nsec=x11, ts_sec=x3, ts_nsec=x4, nsec_to_sec=x9
> -	clock_gettime_return, shift=1
> +	clock_gettime_return shift=1
>   
>   	ALIGN
>   monotonic_raw:
> @@ -271,7 +271,7 @@ monotonic_raw:
>   		clock_nsec=x15, nsec_to_sec=x9
>   
>   	add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
> -	clock_gettime_return, shift=1
> +	clock_gettime_return shift=1
>   
>   	ALIGN
>   realtime_coarse:
> 

Re: [PATCH 4.19 ONLY v4] arm64: vdso: remove commas between macro name and arguments

[Greg KH]

On Thu, May 06, 2021 at 10:43:33AM -0700, Nathan Chancellor wrote:
> On 5/5/2021 6:25 PM, Jian Cai wrote:
> > LLVM's integrated assembler appears to assume an argument with default
> > value is passed whenever it sees a comma right after the macro name.
> > It will be fine if the number of following arguments is one less than
> > the number of parameters specified in the macro definition. Otherwise,
> > it fails. For example, the following code works:
> > 
> > $ cat foo.s
> > .macro  foo arg1=2, arg2=4
> >          ldr r0, [r1, #\arg1]
> >          ldr r0, [r1, #\arg2]
> > .endm
> > 
> > foo, arg2=8
> > 
> > $ llvm-mc -triple=armv7a -filetype=obj foo.s -o ias.o
> > arm-linux-gnueabihf-objdump -dr ias.o
> > 
> > ias.o:     file format elf32-littlearm
> > 
> > Disassembly of section .text:
> > 
> > 00000000 <.text>:
> >     0: e5910001 ldr r0, [r1, #2]
> >     4: e5910003 ldr r0, [r1, #8]
> > 
> > While the the following code would fail:
> > 
> > $ cat foo.s
> > .macro  foo arg1=2, arg2=4
> >          ldr r0, [r1, #\arg1]
> >          ldr r0, [r1, #\arg2]
> > .endm
> > 
> > foo, arg1=2, arg2=8
> > 
> > $ llvm-mc -triple=armv7a -filetype=obj foo.s -o ias.o
> > foo.s:6:14: error: too many positional arguments
> > foo, arg1=2, arg2=8
> > 
> > This causes build failures as follows:
> > 
> > arch/arm64/kernel/vdso/gettimeofday.S:230:24: error: too many positional
> > arguments
> >   clock_gettime_return, shift=1
> >                         ^
> > arch/arm64/kernel/vdso/gettimeofday.S:253:24: error: too many positional
> > arguments
> >   clock_gettime_return, shift=1
> >                         ^
> > arch/arm64/kernel/vdso/gettimeofday.S:274:24: error: too many positional
> > arguments
> >   clock_gettime_return, shift=1
> > 
> > This error is not in mainline because commit 28b1a824a4f4 ("arm64: vdso:
> > Substitute gettimeofday() with C implementation") rewrote this assembler
> > file in C as part of a 25 patch series that is unsuitable for stable.
> > Just remove the comma in the clock_gettime_return invocations in 4.19 so
> > that GNU as and LLVM's integrated assembler work the same.
> > 
> > Link:
> > https://github.com/ClangBuiltLinux/linux/issues/1349
> > 
> > Suggested-by: Nathan Chancellor <nathan@kernel.org>
> > Signed-off-by: Jian Cai <jiancai@google.com>
> 
> Thanks for the updated example and explanation, this looks good to me now.
> 
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>

Now queued up, thanks.

greg k-h