diff options
Diffstat (limited to 'arch/x86/kernel/alternative.c')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 111 |
1 files changed, 74 insertions, 37 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 91b1cdd16569..741d8767ddf8 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -6,6 +6,9 @@ #include <linux/vmalloc.h> #include <linux/memory.h> #include <linux/execmem.h> +#include <linux/cleanup.h> +#include <linux/kgdb.h> +#include <linux/mmap_lock.h> #include <asm/text-patching.h> #include <asm/insn.h> @@ -1198,6 +1201,41 @@ static bool cfi_debug __ro_after_init; bool cfi_bhi __ro_after_init = false; #endif +#ifdef CONFIG_FINEIBT +/* + * <fineibt_preamble_start>: + * 0: f3 0f 1e fa endbr64 + * 4: 2d 78 56 34 12 sub $0x12345678, %eax + * 9: 2e 0f 85 03 00 00 00 jne,pn 13 <fineibt_preamble_start+0x13> + * 10: 0f 1f 40 d6 nopl -0x2a(%rax) + * + * Note that the JNE target is the 0xD6 byte inside the NOPL, this decodes as + * UDB on x86_64 and raises #UD. + */ +asm( ".pushsection .rodata \n" + "fineibt_preamble_start: \n" + " endbr64 \n" + " subl $0x12345678, %eax \n" + "fineibt_preamble_bhi: \n" + " cs jne.d32 fineibt_preamble_start+0x13 \n" + "#fineibt_func: \n" + " nopl -42(%rax) \n" + "fineibt_preamble_end: \n" + ".popsection\n" +); + +extern u8 fineibt_preamble_start[]; +extern u8 fineibt_preamble_bhi[]; +extern u8 fineibt_preamble_end[]; + +#define fineibt_preamble_size (fineibt_preamble_end - fineibt_preamble_start) +#define fineibt_preamble_bhi (fineibt_preamble_bhi - fineibt_preamble_start) +#define fineibt_preamble_ud 0x13 +#define fineibt_preamble_hash 5 + +#define fineibt_prefix_size (fineibt_preamble_size - ENDBR_INSN_SIZE) +#endif /* CONFIG_FINEIBT */ + #ifdef CONFIG_CFI u32 cfi_get_func_hash(void *func) { @@ -1205,9 +1243,11 @@ u32 cfi_get_func_hash(void *func) func -= cfi_get_offset(); switch (cfi_mode) { +#ifdef CONFIG_FINEIBT case CFI_FINEIBT: - func += 7; + func += fineibt_preamble_hash; break; +#endif case CFI_KCFI: func += 1; break; @@ -1364,39 +1404,6 @@ early_param("cfi", cfi_parse_cmdline); */ /* - * <fineibt_preamble_start>: - * 0: f3 0f 1e fa endbr64 - * 4: 2d 78 56 34 12 sub $0x12345678, %eax - * 9: 2e 0f 85 03 00 00 00 jne,pn 13 <fineibt_preamble_start+0x13> - * 10: 0f 1f 40 d6 nopl -0x2a(%rax) - * - * Note that the JNE target is the 0xD6 byte inside the NOPL, this decodes as - * UDB on x86_64 and raises #UD. - */ -asm( ".pushsection .rodata \n" - "fineibt_preamble_start: \n" - " endbr64 \n" - " subl $0x12345678, %eax \n" - "fineibt_preamble_bhi: \n" - " cs jne.d32 fineibt_preamble_start+0x13 \n" - "#fineibt_func: \n" - " nopl -42(%rax) \n" - "fineibt_preamble_end: \n" - ".popsection\n" -); - -extern u8 fineibt_preamble_start[]; -extern u8 fineibt_preamble_bhi[]; -extern u8 fineibt_preamble_end[]; - -#define fineibt_preamble_size (fineibt_preamble_end - fineibt_preamble_start) -#define fineibt_preamble_bhi (fineibt_preamble_bhi - fineibt_preamble_start) -#define fineibt_preamble_ud 0x13 -#define fineibt_preamble_hash 5 - -#define fineibt_prefix_size (fineibt_preamble_size - ENDBR_INSN_SIZE) - -/* * <fineibt_caller_start>: * 0: b8 78 56 34 12 mov $0x12345678, %eax * 5: 4d 8d 5b f0 lea -0x10(%r11), %r11 @@ -2372,6 +2379,38 @@ static void text_poke_memset(void *dst, const void *src, size_t len) typedef void text_poke_f(void *dst, const void *src, size_t len); +static void __poke_vmalloc_pages(struct page **pages, void *addr, + bool cross_page_boundary) +{ + pages[0] = vmalloc_to_page(addr); + if (cross_page_boundary) + pages[1] = vmalloc_to_page(addr + PAGE_SIZE); +} + +static void poke_vmalloc_pages(struct page **pages, void *addr, + bool cross_page_boundary) +{ + if (in_dbg_master()) { + /* + * If called from kgdb cannot sleep, but all other CPUs stopped + * anyway so safe to proceed without locks + */ + __poke_vmalloc_pages(pages, addr, cross_page_boundary); + } else { + /* + * execmem ROX ranges are shared between modules and can be + * collapsed to huge PMD entries, and this collapse can happen + * concurrently with a racing set_memory_rox(). + * + * Prevent vmalloc_to_page() from racing by acquiring an + * init_mm read lock which pairs with the init_mm write lock in + * cpa_collapse_large_pages(). + */ + guard(mmap_read_lock)(&init_mm); + __poke_vmalloc_pages(pages, addr, cross_page_boundary); + } +} + static void *__text_poke(text_poke_f func, void *addr, const void *src, size_t len) { bool cross_page_boundary = offset_in_page(addr) + len > PAGE_SIZE; @@ -2389,9 +2428,7 @@ static void *__text_poke(text_poke_f func, void *addr, const void *src, size_t l BUG_ON(!after_bootmem); if (!core_kernel_text((unsigned long)addr)) { - pages[0] = vmalloc_to_page(addr); - if (cross_page_boundary) - pages[1] = vmalloc_to_page(addr + PAGE_SIZE); + poke_vmalloc_pages(pages, addr, cross_page_boundary); } else { pages[0] = virt_to_page(addr); WARN_ON(!PageReserved(pages[0])); |