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-rw-r--r--arch/Kconfig7
-rw-r--r--arch/x86/Kconfig1
-rw-r--r--arch/x86/include/asm/ptrace.h38
3 files changed, 46 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 9d329608913e..ed27fd262627 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -290,6 +290,13 @@ config HAVE_RSEQ
This symbol should be selected by an architecture if it
supports an implementation of restartable sequences.
+config HAVE_FUNCTION_ARG_ACCESS_API
+ bool
+ help
+ This symbol should be selected by an architecure if it supports
+ the API needed to access function arguments from pt_regs,
+ declared in asm/ptrace.h
+
config HAVE_CLK
bool
help
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cbd5f28ea8e2..ffebfc3f43c1 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -186,6 +186,7 @@ config X86
select HAVE_RCU_TABLE_INVALIDATE if HAVE_RCU_TABLE_FREE
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
+ select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
select HAVE_STACK_VALIDATION if X86_64
select HAVE_RSEQ
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 143c99499531..8a7fc0cca2d1 100644
--- 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)