[PATCH 1/3] modpost: move __attribute__((format(printf, 2, 3))) to modpost.h

[PATCH 1/3] modpost: move __attribute__((format(printf, 2, 3))) to modpost.h

[Masahiro Yamada]

This attribute must be added to the function declaration in a header
for comprehensive checking of all the callsites.

Fixes: 6d9a89ea4b06 ("kbuild: declare the modpost error functions as printf like")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/mod/modpost.c | 3 +--
 scripts/mod/modpost.h | 3 ++-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index cb6406f485a9..ca0a90158f85 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -60,8 +60,7 @@ static unsigned int nr_unresolved;
 
 #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
 
-void __attribute__((format(printf, 2, 3)))
-modpost_log(enum loglevel loglevel, const char *fmt, ...)
+void modpost_log(enum loglevel loglevel, const char *fmt, ...)
 {
 	va_list arglist;
 
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 69baf014da4f..9fe974dc1a52 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -197,7 +197,8 @@ enum loglevel {
 	LOG_FATAL
 };
 
-void modpost_log(enum loglevel loglevel, const char *fmt, ...);
+void __attribute__((format(printf, 2, 3)))
+modpost_log(enum loglevel loglevel, const char *fmt, ...);
 
 /*
  * warn - show the given message, then let modpost continue running, still
-- 
2.40.1

[PATCH 2/3] modpost: remove unreachable code after fatal()

[Masahiro Yamada]

fatal() never returns. Remove unreachable code.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/mod/modpost.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index ca0a90158f85..013fc5031bc7 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -473,11 +473,9 @@ static int parse_elf(struct elf_info *info, const char *filename)
 		fatal("%s: not relocatable object.", filename);
 
 	/* Check if file offset is correct */
-	if (hdr->e_shoff > info->size) {
+	if (hdr->e_shoff > info->size)
 		fatal("section header offset=%lu in file '%s' is bigger than filesize=%zu\n",
 		      (unsigned long)hdr->e_shoff, filename, info->size);
-		return 0;
-	}
 
 	if (hdr->e_shnum == SHN_UNDEF) {
 		/*
@@ -515,12 +513,11 @@ static int parse_elf(struct elf_info *info, const char *filename)
 		const char *secname;
 		int nobits = sechdrs[i].sh_type == SHT_NOBITS;
 
-		if (!nobits && sechdrs[i].sh_offset > info->size) {
+		if (!nobits && sechdrs[i].sh_offset > info->size)
 			fatal("%s is truncated. sechdrs[i].sh_offset=%lu > sizeof(*hrd)=%zu\n",
 			      filename, (unsigned long)sechdrs[i].sh_offset,
 			      sizeof(*hdr));
-			return 0;
-		}
+
 		secname = secstrings + sechdrs[i].sh_name;
 		if (strcmp(secname, ".modinfo") == 0) {
 			if (nobits)
-- 
2.40.1

[PATCH 3/3] modpost: move exit(1) for fatal() to modpost.h

[Masahiro Yamada]

fatal() never returns, but compilers are not aware of this fact because
exit(1) is called within the modpost_log() definition.

Move exit(1) to the fatal() macro so that compilers can identify
unreachable code flows.

Remove the initializer for 'taddr' in section_rel(), as compilers now
recognize this is not an uninitialized bug.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/mod/modpost.c | 4 +---
 scripts/mod/modpost.h | 2 +-
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 013fc5031bc7..696c583a14ec 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -84,8 +84,6 @@ void modpost_log(enum loglevel loglevel, const char *fmt, ...)
 	vfprintf(stderr, fmt, arglist);
 	va_end(arglist);
 
-	if (loglevel == LOG_FATAL)
-		exit(1);
 	if (loglevel == LOG_ERROR)
 		error_occurred = true;
 }
@@ -1415,7 +1413,7 @@ static void section_rel(struct module *mod, struct elf_info *elf,
 
 	for (rel = start; rel < stop; rel++) {
 		Elf_Sym *tsym;
-		Elf_Addr taddr = 0, r_offset;
+		Elf_Addr taddr, r_offset;
 		unsigned int r_type, r_sym;
 		void *loc;
 
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 9fe974dc1a52..aaa67b24775e 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -215,4 +215,4 @@ modpost_log(enum loglevel loglevel, const char *fmt, ...);
  */
 #define warn(fmt, args...)	modpost_log(LOG_WARN, fmt, ##args)
 #define error(fmt, args...)	modpost_log(LOG_ERROR, fmt, ##args)
-#define fatal(fmt, args...)	modpost_log(LOG_FATAL, fmt, ##args)
+#define fatal(fmt, args...)	do { modpost_log(LOG_FATAL, fmt, ##args); exit(1); } while (1)
-- 
2.40.1

Re: [PATCH 1/3] modpost: move __attribute__((format(printf, 2, 3))) to modpost.h

[Nathan Chancellor]

On Sat, Nov 25, 2023 at 07:31:14PM +0900, Masahiro Yamada wrote:
> This attribute must be added to the function declaration in a header
> for comprehensive checking of all the callsites.
> 
> Fixes: 6d9a89ea4b06 ("kbuild: declare the modpost error functions as printf like")
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

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

> ---
> 
>  scripts/mod/modpost.c | 3 +--
>  scripts/mod/modpost.h | 3 ++-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index cb6406f485a9..ca0a90158f85 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -60,8 +60,7 @@ static unsigned int nr_unresolved;
>  
>  #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
>  
> -void __attribute__((format(printf, 2, 3)))
> -modpost_log(enum loglevel loglevel, const char *fmt, ...)
> +void modpost_log(enum loglevel loglevel, const char *fmt, ...)
>  {
>  	va_list arglist;
>  
> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index 69baf014da4f..9fe974dc1a52 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -197,7 +197,8 @@ enum loglevel {
>  	LOG_FATAL
>  };
>  
> -void modpost_log(enum loglevel loglevel, const char *fmt, ...);
> +void __attribute__((format(printf, 2, 3)))
> +modpost_log(enum loglevel loglevel, const char *fmt, ...);
>  
>  /*
>   * warn - show the given message, then let modpost continue running, still
> -- 
> 2.40.1
> 

Re: [PATCH 2/3] modpost: remove unreachable code after fatal()

[Nathan Chancellor]

On Sat, Nov 25, 2023 at 07:31:15PM +0900, Masahiro Yamada wrote:
> fatal() never returns. Remove unreachable code.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

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

> ---
> 
>  scripts/mod/modpost.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index ca0a90158f85..013fc5031bc7 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -473,11 +473,9 @@ static int parse_elf(struct elf_info *info, const char *filename)
>  		fatal("%s: not relocatable object.", filename);
>  
>  	/* Check if file offset is correct */
> -	if (hdr->e_shoff > info->size) {
> +	if (hdr->e_shoff > info->size)
>  		fatal("section header offset=%lu in file '%s' is bigger than filesize=%zu\n",
>  		      (unsigned long)hdr->e_shoff, filename, info->size);
> -		return 0;
> -	}
>  
>  	if (hdr->e_shnum == SHN_UNDEF) {
>  		/*
> @@ -515,12 +513,11 @@ static int parse_elf(struct elf_info *info, const char *filename)
>  		const char *secname;
>  		int nobits = sechdrs[i].sh_type == SHT_NOBITS;
>  
> -		if (!nobits && sechdrs[i].sh_offset > info->size) {
> +		if (!nobits && sechdrs[i].sh_offset > info->size)
>  			fatal("%s is truncated. sechdrs[i].sh_offset=%lu > sizeof(*hrd)=%zu\n",
>  			      filename, (unsigned long)sechdrs[i].sh_offset,
>  			      sizeof(*hdr));
> -			return 0;
> -		}
> +
>  		secname = secstrings + sechdrs[i].sh_name;
>  		if (strcmp(secname, ".modinfo") == 0) {
>  			if (nobits)
> -- 
> 2.40.1
> 

Re: [PATCH 3/3] modpost: move exit(1) for fatal() to modpost.h

[Nathan Chancellor]

On Sat, Nov 25, 2023 at 07:31:16PM +0900, Masahiro Yamada wrote:
> fatal() never returns, but compilers are not aware of this fact because
> exit(1) is called within the modpost_log() definition.
> 
> Move exit(1) to the fatal() macro so that compilers can identify
> unreachable code flows.
> 
> Remove the initializer for 'taddr' in section_rel(), as compilers now
> recognize this is not an uninitialized bug.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

While I did not see any warnings when testing, it seems like this patch
should come before patch 2 to avoid any potential problems from dropping
the unreachable code (since the compiler won't be able to infer that
fatal() is __noreturn without this change); doesn't really matter though
so:

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

> ---
> 
>  scripts/mod/modpost.c | 4 +---
>  scripts/mod/modpost.h | 2 +-
>  2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 013fc5031bc7..696c583a14ec 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -84,8 +84,6 @@ void modpost_log(enum loglevel loglevel, const char *fmt, ...)
>  	vfprintf(stderr, fmt, arglist);
>  	va_end(arglist);
>  
> -	if (loglevel == LOG_FATAL)
> -		exit(1);
>  	if (loglevel == LOG_ERROR)
>  		error_occurred = true;
>  }
> @@ -1415,7 +1413,7 @@ static void section_rel(struct module *mod, struct elf_info *elf,
>  
>  	for (rel = start; rel < stop; rel++) {
>  		Elf_Sym *tsym;
> -		Elf_Addr taddr = 0, r_offset;
> +		Elf_Addr taddr, r_offset;
>  		unsigned int r_type, r_sym;
>  		void *loc;
>  
> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index 9fe974dc1a52..aaa67b24775e 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -215,4 +215,4 @@ modpost_log(enum loglevel loglevel, const char *fmt, ...);
>   */
>  #define warn(fmt, args...)	modpost_log(LOG_WARN, fmt, ##args)
>  #define error(fmt, args...)	modpost_log(LOG_ERROR, fmt, ##args)
> -#define fatal(fmt, args...)	modpost_log(LOG_FATAL, fmt, ##args)
> +#define fatal(fmt, args...)	do { modpost_log(LOG_FATAL, fmt, ##args); exit(1); } while (1)
> -- 
> 2.40.1
> 

Re: [PATCH 3/3] modpost: move exit(1) for fatal() to modpost.h

[Masahiro Yamada]

On Thu, Nov 30, 2023 at 9:32 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> On Sat, Nov 25, 2023 at 07:31:16PM +0900, Masahiro Yamada wrote:
> > fatal() never returns, but compilers are not aware of this fact because
> > exit(1) is called within the modpost_log() definition.
> >
> > Move exit(1) to the fatal() macro so that compilers can identify
> > unreachable code flows.
> >
> > Remove the initializer for 'taddr' in section_rel(), as compilers now
> > recognize this is not an uninitialized bug.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
>
> While I did not see any warnings when testing, it seems like this patch
> should come before patch 2 to avoid any potential problems from dropping
> the unreachable code (since the compiler won't be able to infer that
> fatal() is __noreturn without this change); doesn't really matter though
> so:


My eyes spotted 2/3, but I can swap the patch order
and rephase the patch description because clang can
detect the unreachable code.













> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
>
> > ---
> >
> >  scripts/mod/modpost.c | 4 +---
> >  scripts/mod/modpost.h | 2 +-
> >  2 files changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> > index 013fc5031bc7..696c583a14ec 100644
> > --- a/scripts/mod/modpost.c
> > +++ b/scripts/mod/modpost.c
> > @@ -84,8 +84,6 @@ void modpost_log(enum loglevel loglevel, const char *fmt, ...)
> >       vfprintf(stderr, fmt, arglist);
> >       va_end(arglist);
> >
> > -     if (loglevel == LOG_FATAL)
> > -             exit(1);
> >       if (loglevel == LOG_ERROR)
> >               error_occurred = true;
> >  }
> > @@ -1415,7 +1413,7 @@ static void section_rel(struct module *mod, struct elf_info *elf,
> >
> >       for (rel = start; rel < stop; rel++) {
> >               Elf_Sym *tsym;
> > -             Elf_Addr taddr = 0, r_offset;
> > +             Elf_Addr taddr, r_offset;
> >               unsigned int r_type, r_sym;
> >               void *loc;
> >
> > diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> > index 9fe974dc1a52..aaa67b24775e 100644
> > --- a/scripts/mod/modpost.h
> > +++ b/scripts/mod/modpost.h
> > @@ -215,4 +215,4 @@ modpost_log(enum loglevel loglevel, const char *fmt, ...);
> >   */
> >  #define warn(fmt, args...)   modpost_log(LOG_WARN, fmt, ##args)
> >  #define error(fmt, args...)  modpost_log(LOG_ERROR, fmt, ##args)
> > -#define fatal(fmt, args...)  modpost_log(LOG_FATAL, fmt, ##args)
> > +#define fatal(fmt, args...)  do { modpost_log(LOG_FATAL, fmt, ##args); exit(1); } while (1)
> > --
> > 2.40.1
> >
>


-- 
Best Regards
Masahiro Yamada