[PATCH v4 1/2] livepatch, x86/module: Generalize late module relocation locking.
From: Dylan Hatch <hidden>
Date: 2025-05-22 20:52:31
Also in:
live-patching, lkml
Subsystem:
live patching, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Late module relocations are an issue on any arch that supports livepatch, so move the text_mutex locking to the livepatch core code. Signed-off-by: Dylan Hatch <redacted> Acked-by: Song Liu <song@kernel.org> --- arch/x86/kernel/module.c | 8 ++------ kernel/livepatch/core.c | 18 +++++++++++++----- 2 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index ff07558b7ebc6..38767e0047d0c 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c@@ -197,18 +197,14 @@ static int write_relocate_add(Elf64_Shdr *sechdrs, bool early = me->state == MODULE_STATE_UNFORMED; void *(*write)(void *, const void *, size_t) = memcpy; - if (!early) { + if (!early) write = text_poke; - mutex_lock(&text_mutex); - } ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me, write, apply); - if (!early) { + if (!early) text_poke_sync(); - mutex_unlock(&text_mutex); - } return ret; }
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 0e73fac55f8eb..9968441f73510 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c@@ -294,9 +294,10 @@ static int klp_write_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, unsigned int symndx, unsigned int secndx, const char *objname, bool apply) { - int cnt, ret; + int cnt, ret = 0; char sec_objname[MODULE_NAME_LEN]; Elf_Shdr *sec = sechdrs + secndx; + bool early = pmod->state == MODULE_STATE_UNFORMED; /* * Format: .klp.rela.sec_objname.section_name
@@ -319,12 +320,19 @@ static int klp_write_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, sec, sec_objname); if (ret) return ret; - - return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); } - clear_relocate_add(sechdrs, strtab, symndx, secndx, pmod); - return 0; + if (!early) + mutex_lock(&text_mutex); + + if (apply) + ret = apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); + else + clear_relocate_add(sechdrs, strtab, symndx, secndx, pmod); + + if (!early) + mutex_unlock(&text_mutex); + return ret; } int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
--
2.49.0.1151.ga128411c76-goog