This is a note to let you know that I've just added the patch titled
module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
module-treat-exit-sections-the-same-as-init-sections-when-config_module_unload.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 33121347fb1c359bd6e3e680b9f2c6ced5734a81 Mon Sep 17 00:00:00 2001
From: Jessica Yu <jeyu@xxxxxxxxxx>
Date: Tue, 23 Mar 2021 13:15:41 +0100
Subject: module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD
From: Jessica Yu <jeyu@xxxxxxxxxx>
commit 33121347fb1c359bd6e3e680b9f2c6ced5734a81 upstream.
Dynamic code patching (alternatives, jump_label and static_call) can
have sites in __exit code, even it __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, when !CONFIG_MODULE_UNLOAD, the section ordering should look like the
following, 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 changelog]
Link: https://lore.kernel.org/lkml/YFiuphGw0RKehWsQ@gunter/
Link: https://lore.kernel.org/r/20210323142756.11443-1-jeyu@xxxxxxxxxx
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
Cc: Joerg Vehlow <lkml@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/module.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2861,7 +2861,11 @@ void * __weak module_alloc(unsigned long
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)
@@ -3171,11 +3175,6 @@ static int rewrite_section_headers(struc
temporary image. */
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. */
Patches currently in stable-queue which might be from jeyu@xxxxxxxxxx are
queue-5.10/module-treat-exit-sections-the-same-as-init-sections-when-config_module_unload.patch
