Re: [RFC/PATCH] arm64: Rename macro arguments to silence sparse

Re: [RFC/PATCH] arm64: Rename macro arguments to silence sparse

[Stephen Boyd]

On 02/06/2017 05:01 PM, Stephen Boyd wrote:
> When I compile files with sparse, I get these sorts of warnings:
>
> arch/arm64/include/asm/lse.h:14:28: warning: Unknown escape 'l'
> arch/arm64/include/asm/lse.h:14:37: warning: Unknown escape 'l'
> arch/arm64/include/asm/alternative.h:172:28: warning: Unknown escape 'o'
>
> This is because sparse is trying to tokenize these files and sees
> a line like this:
>
>  alternative_insn "\llsc", "\lse", ARM64_HAS_LSE_ATOMICS
>
> It gets past alternative_insn part and then sees the start of a
> string with the double quote character. So sparse starts to parse
> the string (eat_string() in the sparse code) but the string has
> an escape character '\' in it. Sparse sees the escape character,
> so it checks to see if it's an escape sequence, but '\l' isn't.
> This causes sparse to spit out this warning of an unknown escape
> sequence 'l'.
>
> In reality, sparse isn't going to use these macros anyway because
> this whole thing is inside an __ASSEMBLER__ ifdef. One hacky
> solution is to make sparse think it actually is an escape
> sequence by starting the macro arguments with the 'n' character.
> Then sparse will see a \n inside a string, which keeps it silent
> and the assembler doesn't seem to mind either.
>
> Cc: <sparse@vger.kernel.org>

Sorry, supposed to be <linux-sparse@vger.kernel.org>

> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> ---
>  arch/arm64/include/asm/alternative.h | 4 ++--
>  arch/arm64/include/asm/lse.h         | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h
> index 6e1cb8c5af4d..dd393db554c8 100644
> --- a/arch/arm64/include/asm/alternative.h
> +++ b/arch/arm64/include/asm/alternative.h
> @@ -168,8 +168,8 @@ alternative_endif
>  #define _ALTERNATIVE_CFG(insn1, insn2, cap, cfg, ...)	\
>  	alternative_insn insn1, insn2, cap, IS_ENABLED(cfg)
>  
> -.macro user_alt, label, oldinstr, newinstr, cond
> -9999:	alternative_insn "\oldinstr", "\newinstr", \cond
> +.macro user_alt, label, noldinstr, newinstr, cond
> +9999:	alternative_insn "\noldinstr", "\newinstr", \cond
>  	_ASM_EXTABLE 9999b, \label
>  .endm
>  
> diff --git a/arch/arm64/include/asm/lse.h b/arch/arm64/include/asm/lse.h
> index fc756e22c84c..36206d75943d 100644
> --- a/arch/arm64/include/asm/lse.h
> +++ b/arch/arm64/include/asm/lse.h
> @@ -10,8 +10,8 @@
>  
>  .arch_extension	lse
>  
> -.macro alt_lse, llsc, lse
> -	alternative_insn "\llsc", "\lse", ARM64_HAS_LSE_ATOMICS
> +.macro alt_lse, nllsc, nlse
> +	alternative_insn "\nllsc", "\nlse", ARM64_HAS_LSE_ATOMICS
>  .endm
>  
>  #else	/* __ASSEMBLER__ */

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [RFC/PATCH] arm64: Rename macro arguments to silence sparse

[Luc Van Oostenryck]

On Mon, Feb 06, 2017 at 05:08:17PM -0800, Stephen Boyd wrote:
> On 02/06/2017 05:01 PM, Stephen Boyd wrote:
> > When I compile files with sparse, I get these sorts of warnings:
> >
> > arch/arm64/include/asm/lse.h:14:28: warning: Unknown escape 'l'
> > arch/arm64/include/asm/lse.h:14:37: warning: Unknown escape 'l'
> > arch/arm64/include/asm/alternative.h:172:28: warning: Unknown escape 'o'
> >
> > This is because sparse is trying to tokenize these files and sees
> > a line like this:
> >
> >  alternative_insn "\llsc", "\lse", ARM64_HAS_LSE_ATOMICS
> >
> > It gets past alternative_insn part and then sees the start of a
> > string with the double quote character. So sparse starts to parse
> > the string (eat_string() in the sparse code) but the string has
> > an escape character '\' in it. Sparse sees the escape character,
> > so it checks to see if it's an escape sequence, but '\l' isn't.
> > This causes sparse to spit out this warning of an unknown escape
> > sequence 'l'.
> >
> > In reality, sparse isn't going to use these macros anyway because
> > this whole thing is inside an __ASSEMBLER__ ifdef.

Yes, annoying. Conversion of escaped characters is supposed to be
done just after preprocessing. It's definitively a bug.

Luc


From 786877f6fa5a3b49c92ef08b28c19e58b75ba8e8 Mon Sep 17 00:00:00 2001
From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Date: Tue, 7 Feb 2017 02:37:00 +0100
Subject: [PATCH] add testcase for wrong early escape conversion

Reported-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 validation/preprocessor/early-escape.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 validation/preprocessor/early-escape.c

diff --git a/validation/preprocessor/early-escape.c b/validation/preprocessor/early-escape.c
new file mode 100644
index 000000000..c7beba5d8
--- /dev/null
+++ b/validation/preprocessor/early-escape.c
@@ -0,0 +1,23 @@
+#if 0
+"\l"
+#endif
+
+/*
+ * check-description:
+ *	Following the C standard, escape conversion must be
+ *	done in phase 5, just after preprocessing and just
+ *	before string concatenation. So we're not supposed
+ *	to receive a diagnostic for an unknown escape char
+ *	for a token which is excluded by the preprocessor.
+ * check-name: early-escape
+ * check-command: sparse -E $file
+ * check-known-to-fail
+ *
+ * check-output-start
+
+
+ * check-output-end
+ *
+ * check-error-start
+ * check-error-end
+ */
-- 
2.11.0

Re: [RFC/PATCH] arm64: Rename macro arguments to silence sparse

[Stephen Boyd]

On 02/06/2017 05:50 PM, Luc Van Oostenryck wrote:
> On Mon, Feb 06, 2017 at 05:08:17PM -0800, Stephen Boyd wrote:
>> On 02/06/2017 05:01 PM, Stephen Boyd wrote:
>>> When I compile files with sparse, I get these sorts of warnings:
>>>
>>> arch/arm64/include/asm/lse.h:14:28: warning: Unknown escape 'l'
>>> arch/arm64/include/asm/lse.h:14:37: warning: Unknown escape 'l'
>>> arch/arm64/include/asm/alternative.h:172:28: warning: Unknown escape 'o'
>>>
>>> This is because sparse is trying to tokenize these files and sees
>>> a line like this:
>>>
>>>  alternative_insn "\llsc", "\lse", ARM64_HAS_LSE_ATOMICS
>>>
>>> It gets past alternative_insn part and then sees the start of a
>>> string with the double quote character. So sparse starts to parse
>>> the string (eat_string() in the sparse code) but the string has
>>> an escape character '\' in it. Sparse sees the escape character,
>>> so it checks to see if it's an escape sequence, but '\l' isn't.
>>> This causes sparse to spit out this warning of an unknown escape
>>> sequence 'l'.
>>>
>>> In reality, sparse isn't going to use these macros anyway because
>>> this whole thing is inside an __ASSEMBLER__ ifdef.
> Yes, annoying. Conversion of escaped characters is supposed to be
> done just after preprocessing. It's definitively a bug.

Ok. Thanks for the fixes to sparse. My hack patch can be safely ignored.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [RFC/PATCH] arm64: Rename macro arguments to silence sparse

[Van Oostenryck Luc]

On Tue, Feb 7, 2017 at 9:11 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 02/06/2017 05:50 PM, Luc Van Oostenryck wrote:
>> On Mon, Feb 06, 2017 at 05:08:17PM -0800, Stephen Boyd wrote:
>>> On 02/06/2017 05:01 PM, Stephen Boyd wrote:
>>>> When I compile files with sparse, I get these sorts of warnings:
>>>>
>>>> arch/arm64/include/asm/lse.h:14:28: warning: Unknown escape 'l'
>>>> arch/arm64/include/asm/lse.h:14:37: warning: Unknown escape 'l'
>>>> arch/arm64/include/asm/alternative.h:172:28: warning: Unknown escape 'o'
>>>>
>>>> This is because sparse is trying to tokenize these files and sees
>>>> a line like this:
>>>>
>>>>  alternative_insn "\llsc", "\lse", ARM64_HAS_LSE_ATOMICS
>>>>
>>>> It gets past alternative_insn part and then sees the start of a
>>>> string with the double quote character. So sparse starts to parse
>>>> the string (eat_string() in the sparse code) but the string has
>>>> an escape character '\' in it. Sparse sees the escape character,
>>>> so it checks to see if it's an escape sequence, but '\l' isn't.
>>>> This causes sparse to spit out this warning of an unknown escape
>>>> sequence 'l'.
>>>>
>>>> In reality, sparse isn't going to use these macros anyway because
>>>> this whole thing is inside an __ASSEMBLER__ ifdef.
>> Yes, annoying. Conversion of escaped characters is supposed to be
>> done just after preprocessing. It's definitively a bug.
>
> Ok. Thanks for the fixes to sparse. My hack patch can be safely ignored.

Well, I don't know.
Maybe it's still useful for everyone using the official version of sparse
or an older one.

Luc Van Oostenryck