Dynamic code patching (alternatives, jump_label and static_call) can
have sites in __exit code, even if __exit is never executed. Therefore
__exit must be present at runtime, at least for as long as __init code
is.
Additionally, for jump_label and static_call, the __exit sites must also
identify as within_module_init(), such that the infrastructure is aware
to never touch them after module init -- alternatives are only ran once
at init and hence don't have this particular constraint.
By making __exit identify as __init for !MODULE_UNLOAD, the above is
satisfied.
So the section ordering should look like the following when
!CONFIG_MODULE_UNLOAD, with the .exit sections moved to the init region of
the module.
Core section allocation order:
.text
.rodata
__ksymtab_gpl
__ksymtab_strings
.note.* sections
.bss
.data
.gnu.linkonce.this_module
Init section allocation order:
.init.text
.exit.text
.symtab
.strtab
[jeyu: thanks to Peter Zijlstra for most of the changelog]
Link: https://lore.kernel.org/lkml/YFiuphGw0RKehWsQ@gunter/
Signed-off-by: Jessica Yu <j...@kernel.org>
---
Do you want to take this patch with the other static_call patches? Or
should I take this through modules-next?
kernel/module.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index 30479355ab85..173a09175511 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2802,7 +2802,11 @@ void * __weak module_alloc(unsigned long size)
bool __weak module_init_section(const char *name)
{
+#ifndef CONFIG_MODULE_UNLOAD
+ return strstarts(name, ".init") || module_exit_section(name);
+#else
return strstarts(name, ".init");
+#endif
}
bool __weak module_exit_section(const char *name)
@@ -3116,11 +3120,6 @@ static int rewrite_section_headers(struct load_info
*info, int flags)
*/
shdr->sh_addr = (size_t)info->hdr + shdr->sh_offset;
-#ifndef CONFIG_MODULE_UNLOAD
- /* Don't load .exit sections */
- if (module_exit_section(info->secstrings+shdr->sh_name))
- shdr->sh_flags &= ~(unsigned long)SHF_ALLOC;
-#endif
}
/* Track but don't keep modinfo and version sections. */
--
2.30.1
