From b1cf540f0e5278ecfe8532557e547d833ed269d7 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 13 Aug 2009 16:34:44 -0400 Subject: x86: Add pt_regs register and stack access APIs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add following APIs for accessing registers and stack entries from pt_regs. These APIs are required by kprobes-based event tracer on ftrace. Some other debugging tools might be able to use it too. - regs_query_register_offset(const char *name) Query the offset of "name" register. - regs_query_register_name(unsigned int offset) Query the name of register by its offset. - regs_get_register(struct pt_regs *regs, unsigned int offset) Get the value of a register by its offset. - regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr) Check the address is in the kernel stack. - regs_get_kernel_stack_nth(struct pt_regs *reg, unsigned int nth) Get Nth entry of the kernel stack. (N >= 0) - regs_get_argument_nth(struct pt_regs *reg, unsigned int nth) Get Nth argument at function call. (N >= 0) Signed-off-by: Masami Hiramatsu Cc: linux-arch@vger.kernel.org Cc: Ananth N Mavinakayanahalli Cc: Avi Kivity Cc: Andi Kleen Cc: Christoph Hellwig Cc: Frank Ch. Eigler Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Jason Baron Cc: Jim Keniston Cc: K.Prasad Cc: Lai Jiangshan Cc: Li Zefan Cc: Przemysław Pawełczyk Cc: Roland McGrath Cc: Sam Ravnborg Cc: Srikar Dronamraju Cc: Steven Rostedt Cc: Tom Zanussi Cc: Vegard Nossum LKML-Reference: <20090813203444.31965.26374.stgit@localhost.localdomain> Signed-off-by: Frederic Weisbecker --- arch/x86/kernel/ptrace.c | 112 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 112 insertions(+) (limited to 'arch/x86/kernel/ptrace.c') diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 8d7d5c9c1be3..a33a17d5d5c8 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -49,6 +49,118 @@ enum x86_regset { REGSET_IOPERM32, }; +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[] = { +#ifdef CONFIG_X86_64 + REG_OFFSET_NAME(r15), + REG_OFFSET_NAME(r14), + REG_OFFSET_NAME(r13), + REG_OFFSET_NAME(r12), + REG_OFFSET_NAME(r11), + REG_OFFSET_NAME(r10), + REG_OFFSET_NAME(r9), + REG_OFFSET_NAME(r8), +#endif + REG_OFFSET_NAME(bx), + REG_OFFSET_NAME(cx), + REG_OFFSET_NAME(dx), + REG_OFFSET_NAME(si), + REG_OFFSET_NAME(di), + REG_OFFSET_NAME(bp), + REG_OFFSET_NAME(ax), +#ifdef CONFIG_X86_32 + REG_OFFSET_NAME(ds), + REG_OFFSET_NAME(es), + REG_OFFSET_NAME(fs), + REG_OFFSET_NAME(gs), +#endif + REG_OFFSET_NAME(orig_ax), + REG_OFFSET_NAME(ip), + REG_OFFSET_NAME(cs), + REG_OFFSET_NAME(flags), + REG_OFFSET_NAME(sp), + REG_OFFSET_NAME(ss), + 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_query_register_name() - query register name from its offset + * @offset: the offset of a register in struct pt_regs. + * + * regs_query_register_name() returns the name of a register from its + * offset in struct pt_regs. If the @offset is invalid, this returns NULL; + */ +const char *regs_query_register_name(unsigned int offset) +{ + const struct pt_regs_offset *roff; + for (roff = regoffset_table; roff->name != NULL; roff++) + if (roff->offset == offset) + return roff->name; + return NULL; +} + +static const int arg_offs_table[] = { +#ifdef CONFIG_X86_32 + [0] = offsetof(struct pt_regs, ax), + [1] = offsetof(struct pt_regs, dx), + [2] = offsetof(struct pt_regs, cx) +#else /* CONFIG_X86_64 */ + [0] = offsetof(struct pt_regs, di), + [1] = offsetof(struct pt_regs, si), + [2] = offsetof(struct pt_regs, dx), + [3] = offsetof(struct pt_regs, cx), + [4] = offsetof(struct pt_regs, r8), + [5] = offsetof(struct pt_regs, r9) +#endif +}; + +/** + * regs_get_argument_nth() - get Nth argument at function call + * @regs: pt_regs which contains registers at function entry. + * @n: argument number. + * + * regs_get_argument_nth() returns @n th argument of a function call. + * Since usually the kernel stack will be changed right after function entry, + * you must use this at function entry. If the @n th entry is NOT in the + * kernel stack or pt_regs, this returns 0. + */ +unsigned long regs_get_argument_nth(struct pt_regs *regs, unsigned int n) +{ + if (n < ARRAY_SIZE(arg_offs_table)) + return *((unsigned long *)regs + arg_offs_table[n]); + else { + /* + * The typical case: arg n is on the stack. + * (Note: stack[0] = return address, so skip it) + */ + n -= ARRAY_SIZE(arg_offs_table); + return regs_get_kernel_stack_nth(regs, 1 + n); + } +} + /* * does not yet catch signals sent when the child dies. * in exit.c or in signal.c. -- cgit v1.2.2