Without this patch, module init sections are disabled by patching their
names in arch-specific code when they're loaded (which prevents code in
layout_sections from finding init sections). This patch uses the new
arch-specific module_init_section instead.

This allows modules that have .init_array sections to have the
initialisers properly called (on load, before init). Without this patch,
the initialisers are not called because .init_array is renamed to
_init_array, and thus isn't found by code in find_module_sections().

Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
---
 arch/powerpc/kernel/module_64.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 5d77d3f5fbb5..6a45e6ddbe58 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -277,6 +277,12 @@ static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
 	return NULL;
 }
 
+bool module_init_section(const char *name)
+{
+	/* We don't handle .init for the moment: always return false. */
+	return false;
+}
+
 int module_frob_arch_sections(Elf64_Ehdr *hdr,
 			      Elf64_Shdr *sechdrs,
 			      char *secstrings,
@@ -286,7 +292,6 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
 
 	/* Find .toc and .stubs sections, symtab and strtab */
 	for (i = 1; i < hdr->e_shnum; i++) {
-		char *p;
 		if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
 			me->arch.stubs_section = i;
 		else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
@@ -298,10 +303,6 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
 			dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
 					  sechdrs[i].sh_size);
 
-		/* We don't handle .init for the moment: rename to _init */
-		while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
-			p[0] = '_';
-
 		if (sechdrs[i].sh_type == SHT_SYMTAB)
 			dedotify((void *)hdr + sechdrs[i].sh_offset,
 				 sechdrs[i].sh_size / sizeof(Elf64_Sym),
-- 
2.35.0.rc2.247.g8bbb082509-goog

Hi Michael,

On Wed, 2 Feb 2022 at 05:53, Wedson Almeida Filho <wedsonaf@google.com> wrote:
>
> Without this patch, module init sections are disabled by patching their
> names in arch-specific code when they're loaded (which prevents code in
> layout_sections from finding init sections). This patch uses the new
> arch-specific module_init_section instead.
>
> This allows modules that have .init_array sections to have the
> initialisers properly called (on load, before init). Without this patch,
> the initialisers are not called because .init_array is renamed to
> _init_array, and thus isn't found by code in find_module_sections().
>
> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
> ---
>  arch/powerpc/kernel/module_64.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
> index 5d77d3f5fbb5..6a45e6ddbe58 100644
> --- a/arch/powerpc/kernel/module_64.c
> +++ b/arch/powerpc/kernel/module_64.c
> @@ -277,6 +277,12 @@ static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
>         return NULL;
>  }
>
> +bool module_init_section(const char *name)
> +{
> +       /* We don't handle .init for the moment: always return false. */
> +       return false;
> +}
> +
>  int module_frob_arch_sections(Elf64_Ehdr *hdr,
>                               Elf64_Shdr *sechdrs,
>                               char *secstrings,
> @@ -286,7 +292,6 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
>
>         /* Find .toc and .stubs sections, symtab and strtab */
>         for (i = 1; i < hdr->e_shnum; i++) {
> -               char *p;
>                 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
>                         me->arch.stubs_section = i;
>                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
> @@ -298,10 +303,6 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
>                         dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
>                                           sechdrs[i].sh_size);
>
> -               /* We don't handle .init for the moment: rename to _init */
> -               while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
> -                       p[0] = '_';
> -
>                 if (sechdrs[i].sh_type == SHT_SYMTAB)
>                         dedotify((void *)hdr + sechdrs[i].sh_offset,
>                                  sechdrs[i].sh_size / sizeof(Elf64_Sym),
> --
> 2.35.0.rc2.247.g8bbb082509-goog

Would any additional clarification from my part be helpful here?

I got an email saying it was under review (and checks passed) but
nothing appears to have happened since.

Cheers,
-Wedson

Wedson Almeida Filho <wedsonaf@google.com> writes:
> Hi Michael,
>
> On Wed, 2 Feb 2022 at 05:53, Wedson Almeida Filho <wedsonaf@google.com> wrote:
>>
>> Without this patch, module init sections are disabled by patching their
>> names in arch-specific code when they're loaded (which prevents code in
>> layout_sections from finding init sections). This patch uses the new
>> arch-specific module_init_section instead.
>>
>> This allows modules that have .init_array sections to have the
>> initialisers properly called (on load, before init). Without this patch,
>> the initialisers are not called because .init_array is renamed to
>> _init_array, and thus isn't found by code in find_module_sections().
>>
>> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
>> ---
>>  arch/powerpc/kernel/module_64.c | 11 ++++++-----
>>  1 file changed, 6 insertions(+), 5 deletions(-)
...
>
> Would any additional clarification from my part be helpful here?

Just more patience ;)

> I got an email saying it was under review (and checks passed) but
> nothing appears to have happened since.

I actually put it in next late last week, but the emails got delayed due
to various gremlins.

cheers

On Wed, 2 Feb 2022 05:51:23 +0000, Wedson Almeida Filho wrote:
> Without this patch, module init sections are disabled by patching their
> names in arch-specific code when they're loaded (which prevents code in
> layout_sections from finding init sections). This patch uses the new
> arch-specific module_init_section instead.
> 
> This allows modules that have .init_array sections to have the
> initialisers properly called (on load, before init). Without this patch,
> the initialisers are not called because .init_array is renamed to
> _init_array, and thus isn't found by code in find_module_sections().
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/module_64: use module_init_section instead of patching names
      https://git.kernel.org/powerpc/c/d4be60fe66b7380530868ceebe549f8eebccacc5

cheers