This is a note to let you know that I've just added the patch titled
module: check for exit sections in layout_sections() instead of module_init_section()
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-check-for-exit-sections-in-layout_sections-instead-of-module_init_section.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 055f23b74b20f2824ce33047b4cf2e2aa856bf3b Mon Sep 17 00:00:00 2001
From: Jessica Yu <jeyu@xxxxxxxxxx>
Date: Wed, 12 May 2021 15:45:46 +0200
Subject: module: check for exit sections in layout_sections() instead of module_init_section()
From: Jessica Yu <jeyu@xxxxxxxxxx>
commit 055f23b74b20f2824ce33047b4cf2e2aa856bf3b upstream.
Previously, when CONFIG_MODULE_UNLOAD=n, the module loader just does not
attempt to load exit sections since it never expects that any code in those
sections will ever execute. However, 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.
Commit 33121347fb1c ("module: treat exit sections the same as init
sections when !CONFIG_MODULE_UNLOAD") solves the requirements of
jump_labels and static_calls by putting the exit sections in the init
region of the module so that they are at least present at init, and
discarded afterwards. It does this by including a check for exit
sections in module_init_section(), so that it also returns true for exit
sections, and the module loader will automatically sort them in the init
region of the module.
However, the solution there was not completely arch-independent. ARM is
a special case where it supplies its own module_{init, exit}_section()
functions. Instead of pushing the exit section checks into
module_init_section(), just implement the exit section check in
layout_sections(), so that we don't have to touch arch-dependent code.
Fixes: 33121347fb1c ("module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD")
Reviewed-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/module.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2280,6 +2280,15 @@ void *__symbol_get(const char *symbol)
}
EXPORT_SYMBOL_GPL(__symbol_get);
+static bool module_init_layout_section(const char *sname)
+{
+#ifndef CONFIG_MODULE_UNLOAD
+ if (module_exit_section(sname))
+ return true;
+#endif
+ return module_init_section(sname);
+}
+
/*
* Ensure that an exported symbol [global namespace] does not already exist
* in the kernel or in some other module's exported symbol table.
@@ -2489,7 +2498,7 @@ static void layout_sections(struct modul
if ((s->sh_flags & masks[m][0]) != masks[m][0]
|| (s->sh_flags & masks[m][1])
|| s->sh_entsize != ~0UL
- || module_init_section(sname))
+ || module_init_layout_section(sname))
continue;
s->sh_entsize = get_offset(mod, &mod->core_layout.size, s, i);
pr_debug("\t%s\n", sname);
@@ -2522,7 +2531,7 @@ static void layout_sections(struct modul
if ((s->sh_flags & masks[m][0]) != masks[m][0]
|| (s->sh_flags & masks[m][1])
|| s->sh_entsize != ~0UL
- || !module_init_section(sname))
+ || !module_init_layout_section(sname))
continue;
s->sh_entsize = (get_offset(mod, &mod->init_layout.size, s, i)
| INIT_OFFSET_MASK);
@@ -2861,11 +2870,7 @@ 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)
Patches currently in stable-queue which might be from jeyu@xxxxxxxxxx are
queue-5.10/module-check-for-exit-sections-in-layout_sections-instead-of-module_init_section.patch
queue-5.10/module-treat-exit-sections-the-same-as-init-sections-when-config_module_unload.patch
