diff options
Diffstat (limited to 'arch/s390/kernel/ftrace.c')
| -rw-r--r-- | arch/s390/kernel/ftrace.c | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index 0b81a784e03..c92a1095327 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -7,13 +7,17 @@ * */ +#include <linux/hardirq.h> #include <linux/uaccess.h> #include <linux/ftrace.h> #include <linux/kernel.h> #include <linux/types.h> #include <asm/lowcore.h> +#ifdef CONFIG_DYNAMIC_FTRACE + void ftrace_disable_code(void); +void ftrace_disable_return(void); void ftrace_call_code(void); void ftrace_nop_code(void); @@ -28,6 +32,7 @@ asm( " .word 0x0024\n" " lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n" " basr %r14,%r1\n" + "ftrace_disable_return:\n" " lg %r14,8(15)\n" " lgr %r0,%r0\n" "0:\n"); @@ -50,6 +55,7 @@ asm( " j 0f\n" " l %r1,"__stringify(__LC_FTRACE_FUNC)"\n" " basr %r14,%r1\n" + "ftrace_disable_return:\n" " l %r14,4(%r15)\n" " j 0f\n" " bcr 0,%r7\n" @@ -130,3 +136,69 @@ int __init ftrace_dyn_arch_init(void *data) *(unsigned long *)data = 0; return 0; } + +#endif /* CONFIG_DYNAMIC_FTRACE */ + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +#ifdef CONFIG_DYNAMIC_FTRACE +/* + * Patch the kernel code at ftrace_graph_caller location: + * The instruction there is branch relative on condition. The condition mask + * is either all ones (always branch aka disable ftrace_graph_caller) or all + * zeroes (nop aka enable ftrace_graph_caller). + * Instruction format for brc is a7m4xxxx where m is the condition mask. + */ +int ftrace_enable_ftrace_graph_caller(void) +{ + unsigned short opcode = 0xa704; + + return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode)); +} + +int ftrace_disable_ftrace_graph_caller(void) +{ + unsigned short opcode = 0xa7f4; + + return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode)); +} + +static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr) +{ + return addr - (ftrace_disable_return - ftrace_disable_code); +} + +#else /* CONFIG_DYNAMIC_FTRACE */ + +static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr) +{ + return addr - MCOUNT_OFFSET_RET; +} + +#endif /* CONFIG_DYNAMIC_FTRACE */ + +/* + * Hook the return address and push it in the stack of return addresses + * in current thread info. + */ +unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent) +{ + struct ftrace_graph_ent trace; + + /* Nmi's are currently unsupported. */ + if (unlikely(in_nmi())) + goto out; + if (unlikely(atomic_read(¤t->tracing_graph_pause))) + goto out; + if (ftrace_push_return_trace(parent, ip, &trace.depth) == -EBUSY) + goto out; + trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN; + /* Only trace if the calling function expects to. */ + if (!ftrace_graph_entry(&trace)) { + current->curr_ret_stack--; + goto out; + } + parent = (unsigned long)return_to_handler; +out: + return parent; +} +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |