Calling set_memory_rw() and set_memory_ro() for every iteration of the loop in klp_write_object_relocations() is messy, inefficient, and error-prone.
Change all the read-only pages to read-write before the loop and convert them back to read-only again afterwards. Suggested-by: Miroslav Benes <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> --- Based on linux-next. - v3: use new module_{disable,enable}_ro() functions (in linux-next) arch/x86/kernel/livepatch.c | 25 ++----------------------- kernel/livepatch/core.c | 15 ++++++++++----- 2 files changed, 12 insertions(+), 28 deletions(-) diff --git a/arch/x86/kernel/livepatch.c b/arch/x86/kernel/livepatch.c index bcc06e8..92fc1a5 100644 --- a/arch/x86/kernel/livepatch.c +++ b/arch/x86/kernel/livepatch.c @@ -20,8 +20,6 @@ #include <linux/module.h> #include <linux/uaccess.h> -#include <asm/cacheflush.h> -#include <asm/page_types.h> #include <asm/elf.h> #include <asm/livepatch.h> @@ -38,8 +36,7 @@ int klp_write_module_reloc(struct module *mod, unsigned long type, unsigned long loc, unsigned long value) { - int ret, numpages, size = 4; - bool readonly; + size_t size = 4; unsigned long val; unsigned long core = (unsigned long)mod->core_layout.base; unsigned long core_size = mod->core_layout.size; @@ -69,23 +66,5 @@ int klp_write_module_reloc(struct module *mod, unsigned long type, /* loc does not point to any symbol inside the module */ return -EINVAL; - readonly = false; - -#ifdef CONFIG_DEBUG_SET_MODULE_RONX - if (loc < core + mod->core_layout.ro_size) - readonly = true; -#endif - - /* determine if the relocation spans a page boundary */ - numpages = ((loc & PAGE_MASK) == ((loc + size) & PAGE_MASK)) ? 1 : 2; - - if (readonly) - set_memory_rw(loc & PAGE_MASK, numpages); - - ret = probe_kernel_write((void *)loc, &val, size); - - if (readonly) - set_memory_ro(loc & PAGE_MASK, numpages); - - return ret; + return probe_kernel_write((void *)loc, &val, size); } diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index db545cb..7c0ebe1 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -28,6 +28,7 @@ #include <linux/list.h> #include <linux/kallsyms.h> #include <linux/livepatch.h> +#include <asm/cacheflush.h> /** * struct klp_ops - structure for tracking registered ftrace ops structs @@ -283,7 +284,7 @@ static int klp_find_external_symbol(struct module *pmod, const char *name, static int klp_write_object_relocations(struct module *pmod, struct klp_object *obj) { - int ret; + int ret = 0; struct klp_reloc *reloc; if (WARN_ON(!klp_is_object_loaded(obj))) @@ -292,6 +293,8 @@ static int klp_write_object_relocations(struct module *pmod, if (WARN_ON(!obj->relocs)) return -EINVAL; + module_disable_ro(pmod); + for (reloc = obj->relocs; reloc->name; reloc++) { if (!klp_is_module(obj)) { @@ -303,7 +306,7 @@ static int klp_write_object_relocations(struct module *pmod, ret = klp_verify_vmlinux_symbol(reloc->name, reloc->val); if (ret) - return ret; + goto out; } else { /* module, reloc->val needs to be discovered */ if (reloc->external) @@ -315,18 +318,20 @@ static int klp_write_object_relocations(struct module *pmod, reloc->name, &reloc->val); if (ret) - return ret; + goto out; } ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc, reloc->val + reloc->addend); if (ret) { pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n", reloc->name, reloc->val, ret); - return ret; + goto out; } } - return 0; +out: + module_enable_ro(pmod); + return ret; } static void notrace klp_ftrace_handler(unsigned long ip, -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
