diff options
| -rw-r--r-- | arch/x86/Makefile | 20 | ||||
| -rw-r--r-- | arch/x86/entry/entry.S | 2 | ||||
| -rw-r--r-- | arch/x86/entry/entry_64.S | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/processor.h | 16 | ||||
| -rw-r--r-- | arch/x86/include/asm/stackprotector.h | 36 | ||||
| -rw-r--r-- | arch/x86/kernel/asm-offsets_64.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/head_64.S | 3 | ||||
| -rw-r--r-- | arch/x86/xen/xen-head.S | 3 |
9 files changed, 23 insertions, 70 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 5b773b34768d..88a1705366f9 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -140,14 +140,7 @@ ifeq ($(CONFIG_X86_32),y) # temporary until string.h is fixed KBUILD_CFLAGS += -ffreestanding - ifeq ($(CONFIG_STACKPROTECTOR),y) - ifeq ($(CONFIG_SMP),y) - KBUILD_CFLAGS += -mstack-protector-guard-reg=fs \ - -mstack-protector-guard-symbol=__ref_stack_chk_guard - else - KBUILD_CFLAGS += -mstack-protector-guard=global - endif - endif + percpu_seg := fs else BITS := 64 UTS_MACHINE := x86_64 @@ -197,6 +190,17 @@ else KBUILD_CFLAGS += -mcmodel=kernel KBUILD_RUSTFLAGS += -Cno-redzone=y KBUILD_RUSTFLAGS += -Ccode-model=kernel + + percpu_seg := gs +endif + +ifeq ($(CONFIG_STACKPROTECTOR),y) + ifeq ($(CONFIG_SMP),y) + KBUILD_CFLAGS += -mstack-protector-guard-reg=$(percpu_seg) + KBUILD_CFLAGS += -mstack-protector-guard-symbol=__ref_stack_chk_guard + else + KBUILD_CFLAGS += -mstack-protector-guard=global + endif endif # diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S index b7ea3e8e9ecc..fe5344a249a1 100644 --- a/arch/x86/entry/entry.S +++ b/arch/x86/entry/entry.S @@ -52,7 +52,6 @@ EXPORT_SYMBOL_GPL(mds_verw_sel); THUNK warn_thunk_thunk, __warn_thunk -#ifndef CONFIG_X86_64 /* * Clang's implementation of TLS stack cookies requires the variable in * question to be a TLS variable. If the variable happens to be defined as an @@ -66,4 +65,3 @@ THUNK warn_thunk_thunk, __warn_thunk #ifdef CONFIG_STACKPROTECTOR EXPORT_SYMBOL(__ref_stack_chk_guard); #endif -#endif diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index f52dbe0ad93c..33a955aa01d8 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -192,7 +192,7 @@ SYM_FUNC_START(__switch_to_asm) #ifdef CONFIG_STACKPROTECTOR movq TASK_stack_canary(%rsi), %rbx - movq %rbx, PER_CPU_VAR(fixed_percpu_data + FIXED_stack_canary) + movq %rbx, PER_CPU_VAR(__stack_chk_guard) #endif /* diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index c0cd10182e90..a4687122951f 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -422,16 +422,8 @@ struct irq_stack { #ifdef CONFIG_X86_64 struct fixed_percpu_data { - /* - * GCC hardcodes the stack canary as %gs:40. Since the - * irq_stack is the object at %gs:0, we reserve the bottom - * 48 bytes of the irq stack for the canary. - * - * Once we are willing to require -mstack-protector-guard-symbol= - * support for x86_64 stackprotector, we can get rid of this. - */ char gs_base[40]; - unsigned long stack_canary; + unsigned long reserved; }; DECLARE_PER_CPU_FIRST(struct fixed_percpu_data, fixed_percpu_data) __visible; @@ -446,11 +438,7 @@ extern asmlinkage void entry_SYSCALL32_ignore(void); /* Save actual FS/GS selectors and bases to current->thread */ void current_save_fsgs(void); -#else /* X86_64 */ -#ifdef CONFIG_STACKPROTECTOR -DECLARE_PER_CPU(unsigned long, __stack_chk_guard); -#endif -#endif /* !X86_64 */ +#endif /* X86_64 */ struct perf_event; diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h index 00473a650f51..d43fb589fcf6 100644 --- a/arch/x86/include/asm/stackprotector.h +++ b/arch/x86/include/asm/stackprotector.h @@ -2,26 +2,10 @@ /* * GCC stack protector support. * - * Stack protector works by putting predefined pattern at the start of + * Stack protector works by putting a predefined pattern at the start of * the stack frame and verifying that it hasn't been overwritten when - * returning from the function. The pattern is called stack canary - * and unfortunately gcc historically required it to be at a fixed offset - * from the percpu segment base. On x86_64, the offset is 40 bytes. - * - * The same segment is shared by percpu area and stack canary. On - * x86_64, percpu symbols are zero based and %gs (64-bit) points to the - * base of percpu area. The first occupant of the percpu area is always - * fixed_percpu_data which contains stack_canary at the appropriate - * offset. On x86_32, the stack canary is just a regular percpu - * variable. - * - * Putting percpu data in %fs on 32-bit is a minor optimization compared to - * using %gs. Since 32-bit userspace normally has %fs == 0, we are likely - * to load 0 into %fs on exit to usermode, whereas with percpu data in - * %gs, we are likely to load a non-null %gs on return to user mode. - * - * Once we are willing to require GCC 8.1 or better for 64-bit stackprotector - * support, we can remove some of this complexity. + * returning from the function. The pattern is called the stack canary + * and is a unique value for each task. */ #ifndef _ASM_STACKPROTECTOR_H @@ -36,6 +20,8 @@ #include <linux/sched.h> +DECLARE_PER_CPU(unsigned long, __stack_chk_guard); + /* * Initialize the stackprotector canary value. * @@ -51,25 +37,13 @@ static __always_inline void boot_init_stack_canary(void) { unsigned long canary = get_random_canary(); -#ifdef CONFIG_X86_64 - BUILD_BUG_ON(offsetof(struct fixed_percpu_data, stack_canary) != 40); -#endif - current->stack_canary = canary; -#ifdef CONFIG_X86_64 - this_cpu_write(fixed_percpu_data.stack_canary, canary); -#else this_cpu_write(__stack_chk_guard, canary); -#endif } static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle) { -#ifdef CONFIG_X86_64 - per_cpu(fixed_percpu_data.stack_canary, cpu) = idle->stack_canary; -#else per_cpu(__stack_chk_guard, cpu) = idle->stack_canary; -#endif } #else /* STACKPROTECTOR */ diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c index bb65371ea9df..590b6cd0eac0 100644 --- a/arch/x86/kernel/asm-offsets_64.c +++ b/arch/x86/kernel/asm-offsets_64.c @@ -54,11 +54,5 @@ int main(void) BLANK(); #undef ENTRY - BLANK(); - -#ifdef CONFIG_STACKPROTECTOR - OFFSET(FIXED_stack_canary, fixed_percpu_data, stack_canary); - BLANK(); -#endif return 0; } diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 7cce91b19fb2..b71178f0ed6c 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2089,8 +2089,7 @@ void syscall_init(void) if (!cpu_feature_enabled(X86_FEATURE_FRED)) idt_syscall_init(); } - -#else /* CONFIG_X86_64 */ +#endif /* CONFIG_X86_64 */ #ifdef CONFIG_STACKPROTECTOR DEFINE_PER_CPU(unsigned long, __stack_chk_guard); @@ -2099,8 +2098,6 @@ EXPORT_PER_CPU_SYMBOL(__stack_chk_guard); #endif #endif -#endif /* CONFIG_X86_64 */ - /* * Clear all 6 debug registers: */ diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 31345e0ba006..c3d73c04603f 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -361,8 +361,7 @@ SYM_INNER_LABEL(common_startup_64, SYM_L_LOCAL) /* Set up %gs. * - * The base of %gs always points to fixed_percpu_data. If the - * stack protector canary is enabled, it is located at %gs:40. + * The base of %gs always points to fixed_percpu_data. * Note that, on SMP, the boot cpu uses init data section until * the per cpu areas are set up. */ diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index 894edf8d6d62..a31b057e641e 100644 --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -33,8 +33,7 @@ SYM_CODE_START(startup_xen) /* Set up %gs. * - * The base of %gs always points to fixed_percpu_data. If the - * stack protector canary is enabled, it is located at %gs:40. + * The base of %gs always points to fixed_percpu_data. * Note that, on SMP, the boot cpu uses init data section until * the per cpu areas are set up. */ |