From a30b5b03047602be56c5b8ffc3a0e4cfed17561c Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 6 Oct 2021 11:59:29 +0200 Subject: [PATCH] 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 a823c35ff2ed ("arm64: ptrace: Add function argument access API"). Acked-by: Ilya Leoshkevich Reviewed-by: Steffen Maier Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- arch/s390/Kconfig | 1 + arch/s390/include/asm/ptrace.h | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 03eb3ec..c35c98e 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -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 diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h index 662ee21..82fc119 100644 --- a/arch/s390/include/asm/ptrace.h +++ b/arch/s390/include/asm/ptrace.h @@ -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]; -- 2.7.4