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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 a823c35ff2 ("arm64: ptrace: Add
function argument access API").

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2021-10-06 11:59:29 +02:00 committed by Vasily Gorbik
parent 3990b5baf2
commit a30b5b0304
2 changed files with 20 additions and 0 deletions
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1
arch/s390/Kconfig
View File

@ -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

19
arch/s390/include/asm/ptrace.h
View File

@ -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];