From 33121347fb1c359bd6e3e680b9f2c6ced5734a81 Mon Sep 17 00:00:00 2001 From: Jessica Yu Date: Tue, 23 Mar 2021 13:15:41 +0100 Subject: [PATCH] module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD 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@kernel.org Acked-by: Peter Zijlstra (Intel) Signed-off-by: Jessica Yu --- 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. */