From ed1cd6deb013a11959d17a94e35ce159197632da Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Thu, 31 Jan 2019 10:08:58 +0000 Subject: powerpc: Activate CONFIG_THREAD_INFO_IN_TASK This patch activates CONFIG_THREAD_INFO_IN_TASK which moves the thread_info into task_struct. Moving thread_info into task_struct has the following advantages: - It protects thread_info from corruption in the case of stack overflows. - Its address is harder to determine if stack addresses are leaked, making a number of attacks more difficult. This has the following consequences: - thread_info is now located at the beginning of task_struct. - The 'cpu' field is now in task_struct, and only exists when CONFIG_SMP is active. - thread_info doesn't have anymore the 'task' field. This patch: - Removes all recopy of thread_info struct when the stack changes. - Changes the CURRENT_THREAD_INFO() macro to point to current. - Selects CONFIG_THREAD_INFO_IN_TASK. - Modifies raw_smp_processor_id() to get ->cpu from current without including linux/sched.h to avoid circular inclusion and without including asm/asm-offsets.h to avoid symbol names duplication between ASM constants and C constants. - Modifies klp_init_thread_info() to take a task_struct pointer argument. Signed-off-by: Christophe Leroy Reviewed-by: Nicholas Piggin [mpe: Add task_stack.h to livepatch.h to fix build fails] Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/irq.h | 4 ---- arch/powerpc/include/asm/livepatch.h | 7 ++++--- arch/powerpc/include/asm/smp.h | 17 ++++++++++++++++- arch/powerpc/include/asm/thread_info.h | 17 ++--------------- 4 files changed, 22 insertions(+), 23 deletions(-) (limited to 'arch/powerpc/include') diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h index 2efbae8d93be..28a7ace0a1b9 100644 --- a/arch/powerpc/include/asm/irq.h +++ b/arch/powerpc/include/asm/irq.h @@ -51,9 +51,6 @@ struct pt_regs; extern struct thread_info *critirq_ctx[NR_CPUS]; extern struct thread_info *dbgirq_ctx[NR_CPUS]; extern struct thread_info *mcheckirq_ctx[NR_CPUS]; -extern void exc_lvl_ctx_init(void); -#else -#define exc_lvl_ctx_init() #endif /* @@ -62,7 +59,6 @@ extern void exc_lvl_ctx_init(void); extern struct thread_info *hardirq_ctx[NR_CPUS]; extern struct thread_info *softirq_ctx[NR_CPUS]; -extern void irq_ctx_init(void); void call_do_softirq(void *sp); void call_do_irq(struct pt_regs *regs, void *sp); extern void do_IRQ(struct pt_regs *regs); diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h index 47a03b9b528b..5070df19d463 100644 --- a/arch/powerpc/include/asm/livepatch.h +++ b/arch/powerpc/include/asm/livepatch.h @@ -21,6 +21,7 @@ #include #include +#include #ifdef CONFIG_LIVEPATCH static inline int klp_check_compiler_support(void) @@ -43,13 +44,13 @@ static inline unsigned long klp_get_ftrace_location(unsigned long faddr) return ftrace_location_range(faddr, faddr + 16); } -static inline void klp_init_thread_info(struct thread_info *ti) +static inline void klp_init_thread_info(struct task_struct *p) { /* + 1 to account for STACK_END_MAGIC */ - ti->livepatch_sp = (unsigned long *)(ti + 1) + 1; + task_thread_info(p)->livepatch_sp = end_of_stack(p) + 1; } #else -static void klp_init_thread_info(struct thread_info *ti) { } +static inline void klp_init_thread_info(struct task_struct *p) { } #endif /* CONFIG_LIVEPATCH */ #endif /* _ASM_POWERPC_LIVEPATCH_H */ diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h index 41695745032c..0de717e16dd6 100644 --- a/arch/powerpc/include/asm/smp.h +++ b/arch/powerpc/include/asm/smp.h @@ -83,7 +83,22 @@ int is_cpu_dead(unsigned int cpu); /* 32-bit */ extern int smp_hw_index[]; -#define raw_smp_processor_id() (current_thread_info()->cpu) +/* + * This is particularly ugly: it appears we can't actually get the definition + * of task_struct here, but we need access to the CPU this task is running on. + * Instead of using task_struct we're using _TASK_CPU which is extracted from + * asm-offsets.h by kbuild to get the current processor ID. + * + * This also needs to be safeguarded when building asm-offsets.s because at + * that time _TASK_CPU is not defined yet. It could have been guarded by + * _TASK_CPU itself, but we want the build to fail if _TASK_CPU is missing + * when building something else than asm-offsets.s + */ +#ifdef GENERATING_ASM_OFFSETS +#define raw_smp_processor_id() (0) +#else +#define raw_smp_processor_id() (*(unsigned int *)((void *)current + _TASK_CPU)) +#endif #define hard_smp_processor_id() (smp_hw_index[smp_processor_id()]) static inline int get_hard_smp_processor_id(int cpu) diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h index 544cac0474cb..d91523c2c7d8 100644 --- a/arch/powerpc/include/asm/thread_info.h +++ b/arch/powerpc/include/asm/thread_info.h @@ -18,9 +18,9 @@ #define THREAD_SIZE (1 << THREAD_SHIFT) #ifdef CONFIG_PPC64 -#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(clrrdi dest, sp, THREAD_SHIFT) +#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(ld dest, PACACURRENT(r13)) #else -#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(rlwinm dest, sp, 0, 0, 31-THREAD_SHIFT) +#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(mr dest, r2) #endif #ifndef __ASSEMBLY__ @@ -34,8 +34,6 @@ * low level task data. */ struct thread_info { - struct task_struct *task; /* main task structure */ - int cpu; /* cpu we're on */ int preempt_count; /* 0 => preemptable, <0 => BUG */ unsigned long local_flags; /* private flags for thread */ @@ -58,8 +56,6 @@ struct thread_info { */ #define INIT_THREAD_INFO(tsk) \ { \ - .task = &tsk, \ - .cpu = 0, \ .preempt_count = INIT_PREEMPT_COUNT, \ .flags = 0, \ } @@ -67,15 +63,6 @@ struct thread_info { #define THREAD_SIZE_ORDER (THREAD_SHIFT - PAGE_SHIFT) /* how to get the thread information struct from C */ -static inline struct thread_info *current_thread_info(void) -{ - unsigned long val; - - asm (CURRENT_THREAD_INFO(%0,1) : "=r" (val)); - - return (struct thread_info *)val; -} - extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); #ifdef CONFIG_PPC_BOOK3S_64 -- cgit v1.2.3