LLVM's integrated assembler does not support using commas separating
the name and arguments in .macro. However, only spaces are used in the
manual page. This replaces commas between macro names and the subsequent
arguments with space in calls to clock_gettime_return to make it
compatible with IAS.
Link:
https://sourceware.org/binutils/docs/as/Macro.html#Macro
Signed-off-by: Jian Cai <[email protected]>
---
arch/arm64/kernel/vdso/gettimeofday.S | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
index 856fee6d3512..7ee685d9adfc 100644
--- a/arch/arm64/kernel/vdso/gettimeofday.S
+++ b/arch/arm64/kernel/vdso/gettimeofday.S
@@ -122,7 +122,7 @@ x_tmp .req x8
9998:
.endm
- .macro clock_gettime_return, shift=0
+ .macro clock_gettime_return shift=0
.if \shift == 1
lsr x11, x11, x12
.endif
@@ -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:
--
2.31.1.368.gbe11c130af-goog
On Fri, 16 Apr 2021 at 20:16, Jian Cai <[email protected]> wrote:
>
> LLVM's integrated assembler does not support using commas separating
> the name and arguments in .macro. However, only spaces are used in the
> manual page. This replaces commas between macro names and the subsequent
> arguments with space in calls to clock_gettime_return to make it
> compatible with IAS.
>
> Link:
> https://sourceware.org/binutils/docs/as/Macro.html#Macro
> Signed-off-by: Jian Cai <[email protected]>
> ---
> arch/arm64/kernel/vdso/gettimeofday.S | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
> index 856fee6d3512..7ee685d9adfc 100644
> --- a/arch/arm64/kernel/vdso/gettimeofday.S
> +++ b/arch/arm64/kernel/vdso/gettimeofday.S
> @@ -122,7 +122,7 @@ x_tmp .req x8
> 9998:
> .endm
>
> - .macro clock_gettime_return, shift=0
> + .macro clock_gettime_return shift=0
Are you sure the definition needs to be changed as well? The majority
of GAS macros in arch/arm64 (if not all) use a comma after the
identifier, so I would prefer not to deviate from that arbitrarily.
Just look at
$ git grep -E \.macro\\s+\\S+, arch/arm64/*.S
> .if \shift == 1
> lsr x11, x11, x12
> .endif
> @@ -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:
> --
> 2.31.1.368.gbe11c130af-goog
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
I should've mentioned this patch is for 4.19 only as the code has been
rewritten in later versions, but requires a large amount of backports
(https://github.com/ClangBuiltLinux/linux/issues/1349). This is the
only blocker for 4.19 migration to LLVM's integrated assembler on CrOS
that I am aware of.
Thanks,
Jian
On Fri, Apr 16, 2021 at 11:14 AM Jian Cai <[email protected]> wrote:
>
> LLVM's integrated assembler does not support using commas separating
> the name and arguments in .macro. However, only spaces are used in the
> manual page. This replaces commas between macro names and the subsequent
> arguments with space in calls to clock_gettime_return to make it
> compatible with IAS.
>
> Link:
> https://sourceware.org/binutils/docs/as/Macro.html#Macro
> Signed-off-by: Jian Cai <[email protected]>
> ---
> arch/arm64/kernel/vdso/gettimeofday.S | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
> index 856fee6d3512..7ee685d9adfc 100644
> --- a/arch/arm64/kernel/vdso/gettimeofday.S
> +++ b/arch/arm64/kernel/vdso/gettimeofday.S
> @@ -122,7 +122,7 @@ x_tmp .req x8
> 9998:
> .endm
>
> - .macro clock_gettime_return, shift=0
> + .macro clock_gettime_return shift=0
> .if \shift == 1
> lsr x11, x11, x12
> .endif
> @@ -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:
> --
> 2.31.1.368.gbe11c130af-goog
>
LLVM's integrated assembler does not support using commas separating
the name and arguments in .macro. However, only spaces are used in the
manual page. This replaces commas between macro names and the subsequent
arguments with space in calls to clock_gettime_return to make it
compatible with IAS.
Link:
https://sourceware.org/binutils/docs/as/Macro.html#Macro
https://github.com/ClangBuiltLinux/linux/issues/1349
Suggested-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Jian Cai <[email protected]>
---
Changes v1 -> v2:
Keep the comma in the macro definition to be consistent with other
definitions.
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:
--
2.31.1.368.gbe11c130af-goog
On Fri, 16 Apr 2021 at 22:35, Jian Cai <[email protected]> wrote:
>
> LLVM's integrated assembler does not support using commas separating
> the name and arguments in .macro. However, only spaces are used in the
> manual page. This replaces commas between macro names and the subsequent
> arguments with space in calls to clock_gettime_return to make it
> compatible with IAS.
>
> Link:
> https://sourceware.org/binutils/docs/as/Macro.html#Macro
> https://github.com/ClangBuiltLinux/linux/issues/1349
>
> Suggested-by: Ard Biesheuvel <[email protected]>
Please remove this tag - the only thing I suggested was to drop part
of the original patch.
> Signed-off-by: Jian Cai <[email protected]>
> ---
>
> Changes v1 -> v2:
> Keep the comma in the macro definition to be consistent with other
> definitions.
>
> 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:
> --
> 2.31.1.368.gbe11c130af-goog
>
LLVM's integrated assembler does not support using commas separating
the name and arguments in .macro. However, only spaces are used in the
manual page. This replaces commas between macro names and the subsequent
arguments with space in calls to clock_gettime_return to make it
compatible with IAS.
Link:
https://sourceware.org/binutils/docs/as/Macro.html#Macro
https://github.com/ClangBuiltLinux/linux/issues/1349
Signed-off-by: Jian Cai <[email protected]>
---
Changes v1 -> v2:
Keep the comma in the macro definition to be consistent with other
definitions.
Changes v2 -> v3:
Edit tags.
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:
--
2.31.1.368.gbe11c130af-goog
Hi Jian,
On Fri, Apr 16, 2021 at 04:23:41PM -0700, Jian Cai wrote:
> LLVM's integrated assembler does not support using commas separating
> the name and arguments in .macro. However, only spaces are used in the
> manual page. This replaces commas between macro names and the subsequent
> arguments with space in calls to clock_gettime_return to make it
> compatible with IAS.
>
> Link:
> https://sourceware.org/binutils/docs/as/Macro.html#Macro
> https://github.com/ClangBuiltLinux/linux/issues/1349
>
> Signed-off-by: Jian Cai <[email protected]>
The actual patch itself looks fine to me but there should be some more
explanation in the commit message that this patch is for 4.19 only and
why it is not applicable upstream. Additionally, I would recommend using
the '--subject-prefix=' flag to 'git format-patch' to clarify that as
well, something like '--subject-prefix="PATCH 4.19 ONLY"'?
My explanation would be something like (take bits and pieces as you feel
necessary):
========================================================================
[PATCH 4.19 ONLY] arm64: vdso: remove commas between macro name and
arguments
LLVM's integrated assembler does not support using a comma to separate
a macro name and its arguments when there is only one argument with a
default value:
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.
========================================================================
I worded the first sentence the way that I did because correct me if I
am wrong but it seems that the integrated assembler has no issues with
the use of commas separating the arguments in a .macro definition as
that is done everywhere in arch/arm64, just not when there is a single
parameter with a default value because essentially what it is evaluating
it to is "clock_gettime_return ,shift=1", which according to the GAS
manual [1] means that "shift" is actually being set to 0 then there is an
other parameter, when it expects only one.
[1]: After the definition is complete, you can call the macro either as
‘reserve_str a,b’ (with ‘\p1’ evaluating to a and ‘\p2’ evaluating to
b), or as ‘reserve_str ,b’ (with ‘\p1’ evaluating as the default, in
this case ‘0’, and ‘\p2’ evaluating to b).
Lastly, Will or Catalin should ack this as an explicitly out of mainline
patch so that Greg or Sasha can take it. I would put them on the "To:"
line in addition to Greg and Sasha.
Hopefully this is helpful!
Cheers,
Nathan
> ---
>
> Changes v1 -> v2:
> Keep the comma in the macro definition to be consistent with other
> definitions.
>
> Changes v2 -> v3:
> Edit tags.
>
> 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:
> --
> 2.31.1.368.gbe11c130af-goog
>
Fixing Will's email (make sure to run get_maintainer.pl against the
latest kernel tree so that .mailmap can do its thing).
Original thread: https://lore.kernel.org/r/[email protected]/
On Wed, May 05, 2021 at 02:07:14PM -0700, Nathan Chancellor wrote:
> Hi Jian,
>
> On Fri, Apr 16, 2021 at 04:23:41PM -0700, Jian Cai wrote:
> > LLVM's integrated assembler does not support using commas separating
> > the name and arguments in .macro. However, only spaces are used in the
> > manual page. This replaces commas between macro names and the subsequent
> > arguments with space in calls to clock_gettime_return to make it
> > compatible with IAS.
> >
> > Link:
> > https://sourceware.org/binutils/docs/as/Macro.html#Macro
> > https://github.com/ClangBuiltLinux/linux/issues/1349
> >
> > Signed-off-by: Jian Cai <[email protected]>
>
> The actual patch itself looks fine to me but there should be some more
> explanation in the commit message that this patch is for 4.19 only and
> why it is not applicable upstream. Additionally, I would recommend using
> the '--subject-prefix=' flag to 'git format-patch' to clarify that as
> well, something like '--subject-prefix="PATCH 4.19 ONLY"'?
>
> My explanation would be something like (take bits and pieces as you feel
> necessary):
>
> ========================================================================
>
> [PATCH 4.19 ONLY] arm64: vdso: remove commas between macro name and
> arguments
>
> LLVM's integrated assembler does not support using a comma to separate
> a macro name and its arguments when there is only one argument with a
> default value:
>
> 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.
>
> ========================================================================
>
> I worded the first sentence the way that I did because correct me if I
> am wrong but it seems that the integrated assembler has no issues with
> the use of commas separating the arguments in a .macro definition as
> that is done everywhere in arch/arm64, just not when there is a single
> parameter with a default value because essentially what it is evaluating
> it to is "clock_gettime_return ,shift=1", which according to the GAS
> manual [1] means that "shift" is actually being set to 0 then there is an
> other parameter, when it expects only one.
>
> [1]: After the definition is complete, you can call the macro either as
> ‘reserve_str a,b’ (with ‘\p1’ evaluating to a and ‘\p2’ evaluating to
> b), or as ‘reserve_str ,b’ (with ‘\p1’ evaluating as the default, in
> this case ‘0’, and ‘\p2’ evaluating to b).
>
> Lastly, Will or Catalin should ack this as an explicitly out of mainline
> patch so that Greg or Sasha can take it. I would put them on the "To:"
> line in addition to Greg and Sasha.
>
> Hopefully this is helpful!
>
> Cheers,
> Nathan
>
> > ---
> >
> > Changes v1 -> v2:
> > Keep the comma in the macro definition to be consistent with other
> > definitions.
> >
> > Changes v2 -> v3:
> > Edit tags.
> >
> > 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:
> > --
> > 2.31.1.368.gbe11c130af-goog
> >
>
> _______________________________________________
> linux-arm-kernel mailing list
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Hi Nathan,
Please find my comments inlined.
Thanks,
Jian
On Wed, May 5, 2021 at 2:07 PM Nathan Chancellor <[email protected]> wrote:
>
> Hi Jian,
>
> On Fri, Apr 16, 2021 at 04:23:41PM -0700, Jian Cai wrote:
> > LLVM's integrated assembler does not support using commas separating
> > the name and arguments in .macro. However, only spaces are used in the
> > manual page. This replaces commas between macro names and the subsequent
> > arguments with space in calls to clock_gettime_return to make it
> > compatible with IAS.
> >
> > Link:
> > https://sourceware.org/binutils/docs/as/Macro.html#Macro
> > https://github.com/ClangBuiltLinux/linux/issues/1349
> >
> > Signed-off-by: Jian Cai <[email protected]>
>
> The actual patch itself looks fine to me but there should be some more
> explanation in the commit message that this patch is for 4.19 only and
> why it is not applicable upstream. Additionally, I would recommend using
> the '--subject-prefix=' flag to 'git format-patch' to clarify that as
> well, something like '--subject-prefix="PATCH 4.19 ONLY"'?
>
> My explanation would be something like (take bits and pieces as you feel
> necessary):
>
> ========================================================================
>
> [PATCH 4.19 ONLY] arm64: vdso: remove commas between macro name and
> arguments
>
> LLVM's integrated assembler does not support using a comma to separate
> a macro name and its arguments when there is only one argument with a
> default value:
>
> 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.
>
> ========================================================================
>
> I worded the first sentence the way that I did because correct me if I
> am wrong but it seems that the integrated assembler has no issues with
> the use of commas separating the arguments in a .macro definition as
> that is done everywhere in arch/arm64, just not when there is a single
> parameter with a default value because essentially what it is evaluating
> it to is "clock_gettime_return ,shift=1", which according to the GAS
> manual [1] means that "shift" is actually being set to 0 then there is an
> other parameter, when it expects only one.
>
> [1]: After the definition is complete, you can call the macro either as
> ‘reserve_str a,b’ (with ‘\p1’ evaluating to a and ‘\p2’ evaluating to
> b), or as ‘reserve_str ,b’ (with ‘\p1’ evaluating as the default, in
> this case ‘0’, and ‘\p2’ evaluating to b).
Ah you are right! I played with IAS a little and it did not have
problem parsing commas between the name and its arguments in a macro
expansion. However, IAS 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 with the reporter error. This happens to macros with multiple
parameters as well. 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]
```
But the the following code fails,
```
$ 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
```
I will update the commit message accordingly.
> Lastly, Will or Catalin should ack this as an explicitly out of mainline
> patch so that Greg or Sasha can take it. I would put them on the "To:"
> line in addition to Greg and Sasha.
>
> Hopefully this is helpful!
Thanks for the information!
>
> Cheers,
> Nathan
>
> > ---
> >
> > Changes v1 -> v2:
> > Keep the comma in the macro definition to be consistent with other
> > definitions.
> >
> > Changes v2 -> v3:
> > Edit tags.
> >
> > 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:
> > --
> > 2.31.1.368.gbe11c130af-goog
> >
Sorry I sent V4 but forgot to reply to specify message ID, so it is in
its own thread right now:
https://lore.kernel.org/stable/[email protected]/T/#u.
Please let me know if I should also send it to this thread.
Jian
On Wed, May 5, 2021 at 6:03 PM Jian Cai <[email protected]> wrote:
>
> Hi Nathan,
>
> Please find my comments inlined.
>
> Thanks,
> Jian
>
> On Wed, May 5, 2021 at 2:07 PM Nathan Chancellor <[email protected]> wrote:
> >
> > Hi Jian,
> >
> > On Fri, Apr 16, 2021 at 04:23:41PM -0700, Jian Cai wrote:
> > > LLVM's integrated assembler does not support using commas separating
> > > the name and arguments in .macro. However, only spaces are used in the
> > > manual page. This replaces commas between macro names and the subsequent
> > > arguments with space in calls to clock_gettime_return to make it
> > > compatible with IAS.
> > >
> > > Link:
> > > https://sourceware.org/binutils/docs/as/Macro.html#Macro
> > > https://github.com/ClangBuiltLinux/linux/issues/1349
> > >
> > > Signed-off-by: Jian Cai <[email protected]>
> >
> > The actual patch itself looks fine to me but there should be some more
> > explanation in the commit message that this patch is for 4.19 only and
> > why it is not applicable upstream. Additionally, I would recommend using
> > the '--subject-prefix=' flag to 'git format-patch' to clarify that as
> > well, something like '--subject-prefix="PATCH 4.19 ONLY"'?
> >
> > My explanation would be something like (take bits and pieces as you feel
> > necessary):
> >
> > ========================================================================
> >
> > [PATCH 4.19 ONLY] arm64: vdso: remove commas between macro name and
> > arguments
> >
> > LLVM's integrated assembler does not support using a comma to separate
> > a macro name and its arguments when there is only one argument with a
> > default value:
> >
> > 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.
> >
> > ========================================================================
> >
> > I worded the first sentence the way that I did because correct me if I
> > am wrong but it seems that the integrated assembler has no issues with
> > the use of commas separating the arguments in a .macro definition as
> > that is done everywhere in arch/arm64, just not when there is a single
> > parameter with a default value because essentially what it is evaluating
> > it to is "clock_gettime_return ,shift=1", which according to the GAS
> > manual [1] means that "shift" is actually being set to 0 then there is an
> > other parameter, when it expects only one.
> >
> > [1]: After the definition is complete, you can call the macro either as
> > ‘reserve_str a,b’ (with ‘\p1’ evaluating to a and ‘\p2’ evaluating to
> > b), or as ‘reserve_str ,b’ (with ‘\p1’ evaluating as the default, in
> > this case ‘0’, and ‘\p2’ evaluating to b).
>
> Ah you are right! I played with IAS a little and it did not have
> problem parsing commas between the name and its arguments in a macro
> expansion. However, IAS 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 with the reporter error. This happens to macros with multiple
> parameters as well. 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]
> ```
>
> But the the following code fails,
>
> ```
> $ 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
> ```
>
> I will update the commit message accordingly.
>
>
> > Lastly, Will or Catalin should ack this as an explicitly out of mainline
> > patch so that Greg or Sasha can take it. I would put them on the "To:"
> > line in addition to Greg and Sasha.
> >
> > Hopefully this is helpful!
>
> Thanks for the information!
>
> >
> > Cheers,
> > Nathan
> >
> > > ---
> > >
> > > Changes v1 -> v2:
> > > Keep the comma in the macro definition to be consistent with other
> > > definitions.
> > >
> > > Changes v2 -> v3:
> > > Edit tags.
> > >
> > > 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:
> > > --
> > > 2.31.1.368.gbe11c130af-goog
> > >