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  2. linux
  3. [PATCH 0/2] Improve handling of the __klp_{objects,funcs} sections in modules
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[PATCH 2/2] livepatch: Free klp_{object,func}_ext data after initialization

Petr Pavlu posted 2 patches 3 weeks, 4 days ago
There is a newer version of this series
[PATCH 2/2] livepatch: Free klp_{object,func}_ext data after initialization
Posted by Petr Pavlu 3 weeks, 4 days ago 
The klp_object_ext and klp_func_ext data, which are stored in the
__klp_objects and __klp_funcs sections, respectively, are not needed
after they are used to create the actual klp_object and klp_func
instances. This operation is implemented by the init function in
scripts/livepatch/init.c.

Prefix the two sections with ".init" so they are freed after the module
is initializated.

Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---
 kernel/livepatch/core.c             |  3 ++-
 scripts/module.lds.S                |  4 ++--
 tools/objtool/check.c               |  2 +-
 tools/objtool/include/objtool/klp.h | 10 +++++-----
 tools/objtool/klp-diff.c            |  2 +-
 5 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 4e0ac47b3623..3621a7c1b737 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1364,7 +1364,8 @@ struct klp_object_ext *klp_build_locate_init_objects(const struct module *mod,
 	for (int i = 1; i < info->hdr.e_shnum; i++) {
 		Elf_Shdr *shdr = &info->sechdrs[i];
 
-		if (strcmp(info->secstrings + shdr->sh_name, "__klp_objects"))
+		if (strcmp(info->secstrings + shdr->sh_name,
+			   ".init.klp_objects"))
 			continue;
 
 		*nr_objs = shdr->sh_size / sizeof(struct klp_object_ext);
diff --git a/scripts/module.lds.S b/scripts/module.lds.S
index 383d19beffb4..054ef99e8288 100644
--- a/scripts/module.lds.S
+++ b/scripts/module.lds.S
@@ -34,8 +34,8 @@ SECTIONS {
 
 	__patchable_function_entries : { *(__patchable_function_entries) }
 
-	__klp_funcs		0: ALIGN(8) { KEEP(*(__klp_funcs)) }
-	__klp_objects		0: ALIGN(8) { KEEP(*(__klp_objects)) }
+	.init.klp_funcs		0 : ALIGN(8) { KEEP(*(.init.klp_funcs)) }
+	.init.klp_objects	0 : ALIGN(8) { KEEP(*(.init.klp_objects)) }
 
 #ifdef CONFIG_ARCH_USES_CFI_TRAPS
 	__kcfi_traps		: { KEEP(*(.kcfi_traps)) }
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 3f7999317f4d..933868ee3beb 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4761,7 +4761,7 @@ static int validate_ibt(struct objtool_file *file)
 		    !strcmp(sec->name, "__bug_table")			||
 		    !strcmp(sec->name, "__ex_table")			||
 		    !strcmp(sec->name, "__jump_table")			||
-		    !strcmp(sec->name, "__klp_funcs")			||
+		    !strcmp(sec->name, ".init.klp_funcs")		||
 		    !strcmp(sec->name, "__mcount_loc")			||
 		    !strcmp(sec->name, ".llvm.call-graph-profile")	||
 		    !strcmp(sec->name, ".llvm_bb_addr_map")		||
diff --git a/tools/objtool/include/objtool/klp.h b/tools/objtool/include/objtool/klp.h
index ad830a7ce55b..e32e5e8bc631 100644
--- a/tools/objtool/include/objtool/klp.h
+++ b/tools/objtool/include/objtool/klp.h
@@ -6,12 +6,12 @@
 #define SHN_LIVEPATCH		0xff20
 
 /*
- * __klp_objects and __klp_funcs are created by klp diff and used by the patch
- * module init code to build the klp_patch, klp_object and klp_func structs
- * needed by the livepatch API.
+ * .init.klp_objects and .init.klp_funcs are created by klp diff and used by the
+ * patch module init code to build the klp_patch, klp_object and klp_func
+ * structs needed by the livepatch API.
  */
-#define KLP_OBJECTS_SEC	"__klp_objects"
-#define KLP_FUNCS_SEC	"__klp_funcs"
+#define KLP_OBJECTS_SEC	".init.klp_objects"
+#define KLP_FUNCS_SEC	".init.klp_funcs"
 
 /*
  * __klp_relocs is an intermediate section which are created by klp diff and
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index 4d1f9e9977eb..fd64d5e3c3b6 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -1439,7 +1439,7 @@ static int clone_special_sections(struct elfs *e)
 }
 
 /*
- * Create __klp_objects and __klp_funcs sections which are intermediate
+ * Create .init.klp_objects and .init.klp_funcs sections which are intermediate
  * sections provided as input to the patch module's init code for building the
  * klp_patch, klp_object and klp_func structs for the livepatch API.
  */
-- 
2.52.0
Re: [PATCH 2/2] livepatch: Free klp_{object,func}_ext data after initialization
Posted by Joe Lawrence 2 weeks, 6 days ago 
On Wed, Jan 14, 2026 at 01:29:54PM +0100, Petr Pavlu wrote:
> The klp_object_ext and klp_func_ext data, which are stored in the
> __klp_objects and __klp_funcs sections, respectively, are not needed
> after they are used to create the actual klp_object and klp_func
> instances. This operation is implemented by the init function in
> scripts/livepatch/init.c.
> 
> Prefix the two sections with ".init" so they are freed after the module
> is initializated.
> 
> Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
> ---
>  kernel/livepatch/core.c             |  3 ++-
>  scripts/module.lds.S                |  4 ++--
>  tools/objtool/check.c               |  2 +-
>  tools/objtool/include/objtool/klp.h | 10 +++++-----
>  tools/objtool/klp-diff.c            |  2 +-
>  5 files changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 4e0ac47b3623..3621a7c1b737 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -1364,7 +1364,8 @@ struct klp_object_ext *klp_build_locate_init_objects(const struct module *mod,
>  	for (int i = 1; i < info->hdr.e_shnum; i++) {
>  		Elf_Shdr *shdr = &info->sechdrs[i];
>  
> -		if (strcmp(info->secstrings + shdr->sh_name, "__klp_objects"))
> +		if (strcmp(info->secstrings + shdr->sh_name,
> +			   ".init.klp_objects"))
>  			continue;
>  
>  		*nr_objs = shdr->sh_size / sizeof(struct klp_object_ext);
> diff --git a/scripts/module.lds.S b/scripts/module.lds.S
> index 383d19beffb4..054ef99e8288 100644
> --- a/scripts/module.lds.S
> +++ b/scripts/module.lds.S
> @@ -34,8 +34,8 @@ SECTIONS {
>  
>  	__patchable_function_entries : { *(__patchable_function_entries) }
>  
> -	__klp_funcs		0: ALIGN(8) { KEEP(*(__klp_funcs)) }
> -	__klp_objects		0: ALIGN(8) { KEEP(*(__klp_objects)) }
> +	.init.klp_funcs		0 : ALIGN(8) { KEEP(*(.init.klp_funcs)) }
> +	.init.klp_objects	0 : ALIGN(8) { KEEP(*(.init.klp_objects)) }
>  
>  #ifdef CONFIG_ARCH_USES_CFI_TRAPS
>  	__kcfi_traps		: { KEEP(*(.kcfi_traps)) }
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 3f7999317f4d..933868ee3beb 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -4761,7 +4761,7 @@ static int validate_ibt(struct objtool_file *file)
>  		    !strcmp(sec->name, "__bug_table")			||
>  		    !strcmp(sec->name, "__ex_table")			||
>  		    !strcmp(sec->name, "__jump_table")			||
> -		    !strcmp(sec->name, "__klp_funcs")			||
> +		    !strcmp(sec->name, ".init.klp_funcs")		||
>  		    !strcmp(sec->name, "__mcount_loc")			||
>  		    !strcmp(sec->name, ".llvm.call-graph-profile")	||
>  		    !strcmp(sec->name, ".llvm_bb_addr_map")		||
> diff --git a/tools/objtool/include/objtool/klp.h b/tools/objtool/include/objtool/klp.h
> index ad830a7ce55b..e32e5e8bc631 100644
> --- a/tools/objtool/include/objtool/klp.h
> +++ b/tools/objtool/include/objtool/klp.h
> @@ -6,12 +6,12 @@
>  #define SHN_LIVEPATCH		0xff20
>  
>  /*
> - * __klp_objects and __klp_funcs are created by klp diff and used by the patch
> - * module init code to build the klp_patch, klp_object and klp_func structs
> - * needed by the livepatch API.
> + * .init.klp_objects and .init.klp_funcs are created by klp diff and used by the
> + * patch module init code to build the klp_patch, klp_object and klp_func
> + * structs needed by the livepatch API.
>   */
> -#define KLP_OBJECTS_SEC	"__klp_objects"
> -#define KLP_FUNCS_SEC	"__klp_funcs"
> +#define KLP_OBJECTS_SEC	".init.klp_objects"
> +#define KLP_FUNCS_SEC	".init.klp_funcs"
>  
>  /*
>   * __klp_relocs is an intermediate section which are created by klp diff and
> diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
> index 4d1f9e9977eb..fd64d5e3c3b6 100644
> --- a/tools/objtool/klp-diff.c
> +++ b/tools/objtool/klp-diff.c
> @@ -1439,7 +1439,7 @@ static int clone_special_sections(struct elfs *e)
>  }
>  
>  /*
> - * Create __klp_objects and __klp_funcs sections which are intermediate
> + * Create .init.klp_objects and .init.klp_funcs sections which are intermediate
>   * sections provided as input to the patch module's init code for building the
>   * klp_patch, klp_object and klp_func structs for the livepatch API.
>   */
> -- 
> 2.52.0
> 

Acked-by: Joe Lawrence <joe.lawrence@redhat.com>

--
Joe

Patchew 2.1-devel-b67e4c2

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