[PATCH -tip v5 6/7] x86: add pt_regs register and stack access APIs

Masami Hiramatsu
2009-05-09T00:47:19Z

Add following APIs for accessing registers and stack entries from pt_regs.

- query_register_offset(const char *name)
Query the offset of "name" register.

- query_register_name(unsigned offset)
Query the name of register by its offset.

- get_register(struct pt_regs *regs, unsigned offset)
Get the value of a register by its offset.

- valid_stack_address(struct pt_regs *regs, unsigned long addr)
Check the address is in the stack.

- get_stack_nth(struct pt_regs *reg, unsigned nth)
Get Nth entry of the stack. (N >= 0)

- get_argument_nth(struct pt_regs *reg, unsigned nth)
Get Nth argument at function call. (N >= 0)

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Roland McGrath <roland@redhat.com>
---

arch/x86/include/asm/ptrace.h | 66 +++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/ptrace.c | 60 +++++++++++++++++++++++++++++++++++++
2 files changed, 126 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 90b76b3..c316b85 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -7,6 +7,7 @@

#ifdef __KERNEL__
#include <asm/segment.h>
+#include <asm/page_types.h>
#endif

#ifndef __ASSEMBLY__
@@ -215,6 +216,71 @@ static inline unsigned long user_stack_pointer(struct pt_regs *regs)
return regs->sp;
}

+/* Query offset/name of register from its name/offset */
+extern int query_register_offset(const char *name);
+extern const char *query_register_name(unsigned offset);
+#define MAX_REG_OFFSET (offsetof(struct pt_regs, ss))
+
+/* Get register value from its offset */
+static inline unsigned long get_register(struct pt_regs *regs, unsigned offset)
+{
+ if (unlikely(offset > MAX_REG_OFFSET))
+ return 0;
+ return *(unsigned long *)((unsigned long)regs + offset);
+}
+
+/* Check the address in the stack */
+static inline int valid_stack_address(struct pt_regs *regs, unsigned long addr)
+{
+ return ((addr & ~(THREAD_SIZE - 1)) ==
+ (kernel_trap_sp(regs) & ~(THREAD_SIZE - 1)));
+}
+
+/* Get Nth entry of the stack */
+static inline unsigned long get_stack_nth(struct pt_regs *regs, unsigned n)
+{
+ unsigned long *addr = (unsigned long *)kernel_trap_sp(regs);
+ addr += n;
+ if (valid_stack_address(regs, (unsigned long)addr))
+ return *addr;
+ else
+ return 0;
+}
+
+/* Get Nth argument at function call */
+static inline unsigned long get_argument_nth(struct pt_regs *regs, unsigned n)
+{
+#ifdef CONFIG_X86_32
+#define NR_REGPARMS 3
+ if (n < NR_REGPARMS) {
+ switch (n) {
+ case 0: return regs->ax;
+ case 1: return regs->dx;
+ case 2: return regs->cx;
+ }
+ return 0;
+#else /* CONFIG_X86_64 */
+#define NR_REGPARMS 6
+ if (n < NR_REGPARMS) {
+ switch (n) {
+ case 0: return regs->di;
+ case 1: return regs->si;
+ case 2: return regs->dx;
+ case 3: return regs->cx;
+ case 4: return regs->r8;
+ case 5: return regs->r9;
+ }
+ return 0;
+#endif
+ } else {
+ /*
+ * The typical case: arg n is on the stack.
+ * (Note: stack[0] = return address, so skip it)
+ */
+ return get_stack_nth(regs, 1 + n - NR_REGPARMS);
+ }
+}
+
/*
* These are defined as per linux/ptrace.h, which see.
*/
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 09ecbde..00eb9d7 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -48,6 +48,66 @@ enum x86_regset {
REGSET_IOPERM32,
};

+struct pt_regs_offset {
+ const char *name;
+ int offset;
+};
+
+#define REG_OFFSET(r) offsetof(struct pt_regs, r)
+#define REG_OFFSET_NAME(r) {.name = #r, .offset = REG_OFFSET(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,
+};
+
+int 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;
+}
+
+const char *query_register_name(unsigned offset)
+{
+ const struct pt_regs_offset *roff;
+ for (roff = regoffset_table; roff->name != NULL; roff++)
+ if (roff->offset == offset)
+ return roff->name;
+ return NULL;
+}
+
/*
* does not yet catch signals sent when the child dies.
* in exit.c or in signal.c.