Commit a30b5b03 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/ptrace: add function argument access API 



Add regs_get_kernel_argument() which returns Nth argument of a
function call.

This enables ftrace kprobe events to access kernel function arguments
via $argN syntax.

This is the s390 variant of commit a823c35f ("arm64: ptrace: Add
function argument access API").

Acked-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: default avatarSteffen Maier <maier@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 3990b5ba

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -160,6 +160,7 @@ config S390 
	select HAVE_FAST_GUP

	select HAVE_FENTRY

	select HAVE_FTRACE_MCOUNT_RECORD

	select HAVE_FUNCTION_ARG_ACCESS_API

	select HAVE_FUNCTION_ERROR_INJECTION

	select HAVE_FUNCTION_GRAPH_TRACER

	select HAVE_FUNCTION_TRACER

arch/s390/include/asm/ptrace.h

+19 −0
Original line number Diff line number Diff line
@@ -196,6 +196,25 @@ const char *regs_query_register_name(unsigned int offset); 
unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset);

unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n);



/**

 * 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_kernel_argument() returns @n th argument of the function call.

 */

static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,

						     unsigned int n)

{

	unsigned int argoffset = STACK_FRAME_OVERHEAD / sizeof(long);



#define NR_REG_ARGUMENTS 5

	if (n < NR_REG_ARGUMENTS)

		return regs_get_register(regs, 2 + n);

	n -= NR_REG_ARGUMENTS;

	return regs_get_kernel_stack_nth(regs, argoffset + n);

}



static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)

{

	return regs->gprs[15];