Re: [PATCH v3 7/8] x86/kprobes: enable EXECMEM_ROX_CACHE for kprobes allocations
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Date: 2025-07-15 00:21:34
Also in:
linux-mm, linux-modules, lkml
On Sun, 13 Jul 2025 10:17:29 +0300 Mike Rapoport [off-list ref] wrote:
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org> x86::alloc_insn_page() always allocates ROX memory. Instead of overriding this method, add EXECMEM_KPROBES entry in execmem_info with pgprot set to PAGE_KERNEL_ROX and use ROX cache when configuration and CPU features allow it.
Looks good to me. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Thanks!
quoted hunk ↗ jump to hunk
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> --- arch/x86/kernel/kprobes/core.c | 18 ------------------ arch/x86/mm/init.c | 9 ++++++++- 2 files changed, 8 insertions(+), 19 deletions(-)diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 47cb8eb138ba..6079d15dab8c 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c@@ -481,24 +481,6 @@ static int prepare_singlestep(kprobe_opcode_t *buf, struct kprobe *p, return len; } -/* Make page to RO mode when allocate it */ -void *alloc_insn_page(void) -{ - void *page; - - page = execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE); - if (!page) - return NULL; - - /* - * TODO: Once additional kernel code protection mechanisms are set, ensure - * that the page was not maliciously altered and it is still zeroed. - */ - set_memory_rox((unsigned long)page, 1); - - return page; -} - /* Kprobe x86 instruction emulation - only regs->ip or IF flag modifiers */ static void kprobe_emulate_ifmodifiers(struct kprobe *p, struct pt_regs *regs)diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index dbc63f0d538f..442fafd8ff52 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c@@ -1098,7 +1098,14 @@ struct execmem_info __init *execmem_arch_setup(void) .pgprot = pgprot, .alignment = MODULE_ALIGN, }, - [EXECMEM_KPROBES ... EXECMEM_BPF] = { + [EXECMEM_KPROBES] = { + .flags = flags, + .start = start, + .end = MODULES_END, + .pgprot = PAGE_KERNEL_ROX, + .alignment = MODULE_ALIGN, + }, + [EXECMEM_FTRACE ... EXECMEM_BPF] = { .flags = EXECMEM_KASAN_SHADOW, .start = start, .end = MODULES_END,-- 2.47.2
-- Masami Hiramatsu (Google) [off-list ref]