From 88fc078a7a8f67e47020d73d8d14ed11f03754ab Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 29 Apr 2020 10:24:49 -0500 Subject: x86/module: Use text_poke() for late relocations Because of late module patching, a livepatch module needs to be able to apply some of its relocations well after it has been loaded. Instead of playing games with module_{dis,en}able_ro(), use existing text poking mechanisms to apply relocations after module loading. So far only x86, s390 and Power have HAVE_LIVEPATCH but only the first two also have STRICT_MODULE_RWX. This will allow removal of the last module_disable_ro() usage in livepatch. The ultimate goal is to completely disallow making executable mappings writable. [ jpoimboe: Split up patches. Use mod state to determine whether memcpy() can be used. Implement text_poke() for UML. ] Cc: x86@kernel.org Suggested-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Acked-by: Joe Lawrence Acked-by: Miroslav Benes Signed-off-by: Jiri Kosina --- arch/um/kernel/um_arch.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/um/kernel') diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index 0f40eccbd759..375ab720e4aa 100644 --- a/arch/um/kernel/um_arch.c +++ b/arch/um/kernel/um_arch.c @@ -362,3 +362,19 @@ void __init check_bugs(void) void apply_alternatives(struct alt_instr *start, struct alt_instr *end) { } + +void *text_poke(void *addr, const void *opcode, size_t len) +{ + /* + * In UML, the only reference to this function is in + * apply_relocate_add(), which shouldn't ever actually call this + * because UML doesn't have live patching. + */ + WARN_ON(1); + + return memcpy(addr, opcode, len); +} + +void text_poke_sync(void) +{ +} -- cgit v1.2.3-58-ga151