From dcdc7a53a890218a16cd6e2a69e526bd96eb9399 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Patrick=20St=C3=A4hlin?= Date: Thu, 17 Dec 2020 16:01:37 +0000 Subject: [PATCH] RISC-V: Implement ptrace regs and stack API MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Needed for kprobes support. Copied and adapted from arm64 code. Guo Ren fixup pt_regs type for linux-5.8-rc1. Signed-off-by: Patrick Stählin Signed-off-by: Guo Ren Reviewed-by: Pekka Enberg Reviewed-by: Zong Li Reviewed-by: Masami Hiramatsu Signed-off-by: Palmer Dabbelt --- arch/riscv/Kconfig | 1 + arch/riscv/include/asm/ptrace.h | 29 ++++++++++++ arch/riscv/kernel/ptrace.c | 99 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 129 insertions(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 2ef05ef..1027384 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -75,6 +75,7 @@ config RISCV select HAVE_PERF_EVENTS select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP + select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_STACKPROTECTOR select HAVE_SYSCALL_TRACEPOINTS select IRQ_DOMAIN diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h index ee49f80..23372bb 100644 --- a/arch/riscv/include/asm/ptrace.h +++ b/arch/riscv/include/asm/ptrace.h @@ -8,6 +8,7 @@ #include #include +#include #ifndef __ASSEMBLY__ @@ -60,6 +61,7 @@ struct pt_regs { #define user_mode(regs) (((regs)->status & SR_PP) == 0) +#define MAX_REG_OFFSET offsetof(struct pt_regs, orig_a0) /* Helpers for working with the instruction pointer */ static inline unsigned long instruction_pointer(struct pt_regs *regs) @@ -85,6 +87,12 @@ static inline void user_stack_pointer_set(struct pt_regs *regs, regs->sp = val; } +/* Valid only for Kernel mode traps. */ +static inline unsigned long kernel_stack_pointer(struct pt_regs *regs) +{ + return regs->sp; +} + /* Helpers for working with the frame pointer */ static inline unsigned long frame_pointer(struct pt_regs *regs) { @@ -101,6 +109,27 @@ static inline unsigned long regs_return_value(struct pt_regs *regs) return regs->a0; } +extern int regs_query_register_offset(const char *name); +extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, + unsigned int n); + +/** + * regs_get_register() - get register value from its offset + * @regs: pt_regs from which register value is gotten + * @offset: offset of the register. + * + * regs_get_register returns the value of a register whose offset from @regs. + * The @offset is the offset of the register in struct pt_regs. + * If @offset is bigger than MAX_REG_OFFSET, this returns 0. + */ +static inline unsigned long regs_get_register(struct pt_regs *regs, + unsigned int offset) +{ + if (unlikely(offset > MAX_REG_OFFSET)) + return 0; + + return *(unsigned long *)((unsigned long)regs + offset); +} #endif /* __ASSEMBLY__ */ #endif /* _ASM_RISCV_PTRACE_H */ diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c index 2d6395f..1a85305 100644 --- a/arch/riscv/kernel/ptrace.c +++ b/arch/riscv/kernel/ptrace.c @@ -114,6 +114,105 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task) return &riscv_user_native_view; } +struct pt_regs_offset { + const char *name; + int offset; +}; + +#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)} +#define REG_OFFSET_END {.name = NULL, .offset = 0} + +static const struct pt_regs_offset regoffset_table[] = { + REG_OFFSET_NAME(epc), + REG_OFFSET_NAME(ra), + REG_OFFSET_NAME(sp), + REG_OFFSET_NAME(gp), + REG_OFFSET_NAME(tp), + REG_OFFSET_NAME(t0), + REG_OFFSET_NAME(t1), + REG_OFFSET_NAME(t2), + REG_OFFSET_NAME(s0), + REG_OFFSET_NAME(s1), + REG_OFFSET_NAME(a0), + REG_OFFSET_NAME(a1), + REG_OFFSET_NAME(a2), + REG_OFFSET_NAME(a3), + REG_OFFSET_NAME(a4), + REG_OFFSET_NAME(a5), + REG_OFFSET_NAME(a6), + REG_OFFSET_NAME(a7), + REG_OFFSET_NAME(s2), + REG_OFFSET_NAME(s3), + REG_OFFSET_NAME(s4), + REG_OFFSET_NAME(s5), + REG_OFFSET_NAME(s6), + REG_OFFSET_NAME(s7), + REG_OFFSET_NAME(s8), + REG_OFFSET_NAME(s9), + REG_OFFSET_NAME(s10), + REG_OFFSET_NAME(s11), + REG_OFFSET_NAME(t3), + REG_OFFSET_NAME(t4), + REG_OFFSET_NAME(t5), + REG_OFFSET_NAME(t6), + REG_OFFSET_NAME(status), + REG_OFFSET_NAME(badaddr), + REG_OFFSET_NAME(cause), + REG_OFFSET_NAME(orig_a0), + REG_OFFSET_END, +}; + +/** + * regs_query_register_offset() - query register offset from its name + * @name: the name of a register + * + * regs_query_register_offset() returns the offset of a register in struct + * pt_regs from its name. If the name is invalid, this returns -EINVAL; + */ +int regs_query_register_offset(const char *name) +{ + const struct pt_regs_offset *roff; + + for (roff = regoffset_table; roff->name != NULL; roff++) + if (!strcmp(roff->name, name)) + return roff->offset; + return -EINVAL; +} + +/** + * regs_within_kernel_stack() - check the address in the stack + * @regs: pt_regs which contains kernel stack pointer. + * @addr: address which is checked. + * + * regs_within_kernel_stack() checks @addr is within the kernel stack page(s). + * If @addr is within the kernel stack, it returns true. If not, returns false. + */ +static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr) +{ + return (addr & ~(THREAD_SIZE - 1)) == + (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)); +} + +/** + * regs_get_kernel_stack_nth() - get Nth entry of the stack + * @regs: pt_regs which contains kernel stack pointer. + * @n: stack entry number. + * + * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which + * is specified by @regs. If the @n th entry is NOT in the kernel stack, + * this returns 0. + */ +unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n) +{ + unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs); + + addr += n; + if (regs_within_kernel_stack(regs, (unsigned long)addr)) + return *addr; + else + return 0; +} + void ptrace_disable(struct task_struct *child) { clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); -- 2.7.4