Merge tag 'trace-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...

[sfrench/cifs-2.6.git] / arch / x86 / include / asm / ptrace.h

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 143c99499531cc1b0f7d50a7190d211664b7bd8b..8a7fc0cca2d17fde3258d00326327f9ec765c969 100644 (file)
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -286,6 +286,44 @@ static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
        return 0;
 }
 
+/**
+ * regs_get_kernel_argument() - get Nth function argument in kernel
+ * @regs:      pt_regs of that context
+ * @n:         function argument number (start from 0)
+ *
+ * regs_get_argument() returns @n th argument of the function call.
+ * Note that this chooses most probably assignment, in some case
+ * it can be incorrect.
+ * This is expected to be called from kprobes or ftrace with regs
+ * where the top of stack is the return address.
+ */
+static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
+                                                    unsigned int n)
+{
+       static const unsigned int argument_offs[] = {
+#ifdef __i386__
+               offsetof(struct pt_regs, ax),
+               offsetof(struct pt_regs, cx),
+               offsetof(struct pt_regs, dx),
+#define NR_REG_ARGUMENTS 3
+#else
+               offsetof(struct pt_regs, di),
+               offsetof(struct pt_regs, si),
+               offsetof(struct pt_regs, dx),
+               offsetof(struct pt_regs, cx),
+               offsetof(struct pt_regs, r8),
+               offsetof(struct pt_regs, r9),
+#define NR_REG_ARGUMENTS 6
+#endif
+       };
+
+       if (n >= NR_REG_ARGUMENTS) {
+               n -= NR_REG_ARGUMENTS - 1;
+               return regs_get_kernel_stack_nth(regs, n);
+       } else
+               return regs_get_register(regs, argument_offs[n]);
+}
+
 #define arch_has_single_step() (1)
 #ifdef CONFIG_X86_DEBUGCTLMSR
 #define arch_has_block_step()  (1)