2023-10-01 05:47:50

by Masahiro Yamada

Subject: [PATCH 1/2] modpost: refactor check_sec_ref()

We can replace &elf->sechdrs[i] with &sechdrs[i] to slightly shorten
the code because we already have the local variable 'sechdrs'.

However, defining 'sechdr' instead shortens the code further.

Signed-off-by: Masahiro Yamada <[email protected]>
---

scripts/mod/modpost.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 2f3b0fe6f68d..15d78fe152ac 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1523,16 +1523,17 @@ static void section_rel(struct module *mod, struct elf_info *elf,
static void check_sec_ref(struct module *mod, struct elf_info *elf)
{
int i;
- Elf_Shdr *sechdrs = elf->sechdrs;

/* Walk through all sections */
for (i = 0; i < elf->num_sections; i++) {
- check_section(mod->name, elf, &elf->sechdrs[i]);
+ Elf_Shdr *sechdr = &elf->sechdrs[i];
+
+ check_section(mod->name, elf, sechdr);
/* We want to process only relocation sections and not .init */
- if (sechdrs[i].sh_type == SHT_RELA)
- section_rela(mod, elf, &elf->sechdrs[i]);
- else if (sechdrs[i].sh_type == SHT_REL)
- section_rel(mod, elf, &elf->sechdrs[i]);
+ if (sechdr->sh_type == SHT_RELA)
+ section_rela(mod, elf, sechdr);
+ else if (sechdr->sh_type == SHT_REL)
+ section_rel(mod, elf, sechdr);
}
}

--
2.39.2

2023-10-01 05:47:52

by Masahiro Yamada

Subject: [PATCH 2/2] modpost: factor out the common boilerplate of section_rel(a)

The first few lines of section_rel() and section_rela() are the same.
They both retrieve the index of the section to which the relocaton
applies, and skip known-good sections. This common code should be moved
to check_sec_ref().

Avoid ugly casts when computing 'start' and 'stop', and also make the
Elf_Rel and Elf_Rela pointers const.

Signed-off-by: Masahiro Yamada <[email protected]>
---

scripts/mod/modpost.c | 50 ++++++++++++++++++++++---------------------
1 file changed, 26 insertions(+), 24 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 15d78fe152ac..0e18fe617ed1 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1425,17 +1425,10 @@ static void get_rel_type_and_sym(struct elf_info *elf, uint64_t r_info,
}

static void section_rela(struct module *mod, struct elf_info *elf,
- Elf_Shdr *sechdr)
+ unsigned int fsecndx, const char *fromsec,
+ const Elf_Rela *start, const Elf_Rela *stop)
{
- Elf_Rela *rela;
- unsigned int fsecndx = sechdr->sh_info;
- const char *fromsec = sec_name(elf, fsecndx);
- Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset;
- Elf_Rela *stop = (void *)start + sechdr->sh_size;
-
- /* if from section (name) is know good then skip it */
- if (match(fromsec, section_white_list))
- return;
+ const Elf_Rela *rela;

for (rela = start; rela < stop; rela++) {
Elf_Addr taddr, r_offset;
@@ -1465,17 +1458,10 @@ static void section_rela(struct module *mod, struct elf_info *elf,
}

static void section_rel(struct module *mod, struct elf_info *elf,
- Elf_Shdr *sechdr)
+ unsigned int fsecndx, const char *fromsec,
+ const Elf_Rel *start, const Elf_Rel *stop)
{
- Elf_Rel *rel;
- unsigned int fsecndx = sechdr->sh_info;
- const char *fromsec = sec_name(elf, fsecndx);
- Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset;
- Elf_Rel *stop = (void *)start + sechdr->sh_size;
-
- /* if from section (name) is know good then skip it */
- if (match(fromsec, section_white_list))
- return;
+ const Elf_Rel *rel;

for (rel = start; rel < stop; rel++) {
Elf_Sym *tsym;
@@ -1530,10 +1516,26 @@ static void check_sec_ref(struct module *mod, struct elf_info *elf)

check_section(mod->name, elf, sechdr);
/* We want to process only relocation sections and not .init */
- if (sechdr->sh_type == SHT_RELA)
- section_rela(mod, elf, sechdr);
- else if (sechdr->sh_type == SHT_REL)
- section_rel(mod, elf, sechdr);
+ if (sechdr->sh_type == SHT_REL || sechdr->sh_type == SHT_RELA) {
+ /* section to which the relocation applies */
+ unsigned int secndx = sechdr->sh_info;
+ const char *secname = sec_name(elf, secndx);
+ const void *start, *stop;
+
+ /* If the section is known good, skip it */
+ if (match(secname, section_white_list))
+ continue;
+
+ start = sym_get_data_by_offset(elf, i, 0);
+ stop = start + sechdr->sh_size;
+
+ if (sechdr->sh_type == SHT_RELA)
+ section_rela(mod, elf, secndx, secname,
+ start, stop);
+ else
+ section_rel(mod, elf, secndx, secname,
+ start, stop);
+ }
}
}

--
2.39.2

2023-10-02 19:22:11

by Nick Desaulniers

Subject: Re: [PATCH 2/2] modpost: factor out the common boilerplate of section_rel(a)

On Sat, Sep 30, 2023 at 10:47 PM Masahiro Yamada <[email protected]> wrote:
>
> The first few lines of section_rel() and section_rela() are the same.
> They both retrieve the index of the section to which the relocaton

s/relocaton/relocation/

> applies, and skip known-good sections. This common code should be moved
> to check_sec_ref().
>
> Avoid ugly casts when computing 'start' and 'stop', and also make the
> Elf_Rel and Elf_Rela pointers const.
>
> Signed-off-by: Masahiro Yamada <[email protected]>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <[email protected]>

> ---
>
> scripts/mod/modpost.c | 50 ++++++++++++++++++++++---------------------
> 1 file changed, 26 insertions(+), 24 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 15d78fe152ac..0e18fe617ed1 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -1425,17 +1425,10 @@ static void get_rel_type_and_sym(struct elf_info *elf, uint64_t r_info,
> }
>
> static void section_rela(struct module *mod, struct elf_info *elf,
> - Elf_Shdr *sechdr)
> + unsigned int fsecndx, const char *fromsec,
> + const Elf_Rela *start, const Elf_Rela *stop)
> {
> - Elf_Rela *rela;
> - unsigned int fsecndx = sechdr->sh_info;
> - const char *fromsec = sec_name(elf, fsecndx);
> - Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset;
> - Elf_Rela *stop = (void *)start + sechdr->sh_size;
> -
> - /* if from section (name) is know good then skip it */
> - if (match(fromsec, section_white_list))
> - return;
> + const Elf_Rela *rela;
>
> for (rela = start; rela < stop; rela++) {
> Elf_Addr taddr, r_offset;
> @@ -1465,17 +1458,10 @@ static void section_rela(struct module *mod, struct elf_info *elf,
> }
>
> static void section_rel(struct module *mod, struct elf_info *elf,
> - Elf_Shdr *sechdr)
> + unsigned int fsecndx, const char *fromsec,
> + const Elf_Rel *start, const Elf_Rel *stop)
> {
> - Elf_Rel *rel;
> - unsigned int fsecndx = sechdr->sh_info;
> - const char *fromsec = sec_name(elf, fsecndx);
> - Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset;
> - Elf_Rel *stop = (void *)start + sechdr->sh_size;
> -
> - /* if from section (name) is know good then skip it */
> - if (match(fromsec, section_white_list))
> - return;
> + const Elf_Rel *rel;
>
> for (rel = start; rel < stop; rel++) {
> Elf_Sym *tsym;
> @@ -1530,10 +1516,26 @@ static void check_sec_ref(struct module *mod, struct elf_info *elf)
>
> check_section(mod->name, elf, sechdr);
> /* We want to process only relocation sections and not .init */
> - if (sechdr->sh_type == SHT_RELA)
> - section_rela(mod, elf, sechdr);
> - else if (sechdr->sh_type == SHT_REL)
> - section_rel(mod, elf, sechdr);
> + if (sechdr->sh_type == SHT_REL || sechdr->sh_type == SHT_RELA) {
> + /* section to which the relocation applies */
> + unsigned int secndx = sechdr->sh_info;
> + const char *secname = sec_name(elf, secndx);
> + const void *start, *stop;
> +
> + /* If the section is known good, skip it */
> + if (match(secname, section_white_list))
> + continue;
> +
> + start = sym_get_data_by_offset(elf, i, 0);
> + stop = start + sechdr->sh_size;
> +
> + if (sechdr->sh_type == SHT_RELA)
> + section_rela(mod, elf, secndx, secname,
> + start, stop);
> + else
> + section_rel(mod, elf, secndx, secname,
> + start, stop);
> + }
> }
> }
>
> --
> 2.39.2
>


--
Thanks,
~Nick Desaulniers

2023-10-02 22:05:33

by Nick Desaulniers

Subject: Re: [PATCH 1/2] modpost: refactor check_sec_ref()

On Sat, Sep 30, 2023 at 10:47 PM Masahiro Yamada <[email protected]> wrote:
>
> We can replace &elf->sechdrs[i] with &sechdrs[i] to slightly shorten
> the code because we already have the local variable 'sechdrs'.
>
> However, defining 'sechdr' instead shortens the code further.
>
> Signed-off-by: Masahiro Yamada <[email protected]>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <[email protected]>

> ---
>
> scripts/mod/modpost.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 2f3b0fe6f68d..15d78fe152ac 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -1523,16 +1523,17 @@ static void section_rel(struct module *mod, struct elf_info *elf,
> static void check_sec_ref(struct module *mod, struct elf_info *elf)
> {
> int i;
> - Elf_Shdr *sechdrs = elf->sechdrs;
>
> /* Walk through all sections */
> for (i = 0; i < elf->num_sections; i++) {
> - check_section(mod->name, elf, &elf->sechdrs[i]);
> + Elf_Shdr *sechdr = &elf->sechdrs[i];
> +
> + check_section(mod->name, elf, sechdr);
> /* We want to process only relocation sections and not .init */
> - if (sechdrs[i].sh_type == SHT_RELA)
> - section_rela(mod, elf, &elf->sechdrs[i]);
> - else if (sechdrs[i].sh_type == SHT_REL)
> - section_rel(mod, elf, &elf->sechdrs[i]);
> + if (sechdr->sh_type == SHT_RELA)
> + section_rela(mod, elf, sechdr);
> + else if (sechdr->sh_type == SHT_REL)
> + section_rel(mod, elf, sechdr);
> }
> }
>
> --
> 2.39.2
>


--
Thanks,
~Nick Desaulniers