diff options
author | Heiko Carstens | 2009-06-12 10:26:44 +0200 |
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committer | Martin Schwidefsky | 2009-06-12 10:27:38 +0200 |
commit | dfd9f7abc0fb67b5781f340d982384cea53b2884 (patch) | |
tree | 850baae88167699f45ba1dea1765b9156373db72 /arch/s390/kernel/ftrace.c | |
parent | a2b53673fae14601bb520acf6a6f154463994565 (diff) |
[S390] ftrace: add dynamic ftrace support
Dynamic ftrace support for s390.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/ftrace.c')
-rw-r--r-- | arch/s390/kernel/ftrace.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c new file mode 100644 index 000000000000..0b81a784e039 --- /dev/null +++ b/arch/s390/kernel/ftrace.c @@ -0,0 +1,132 @@ +/* + * Dynamic function tracer architecture backend. + * + * Copyright IBM Corp. 2009 + * + * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>, + * + */ + +#include <linux/uaccess.h> +#include <linux/ftrace.h> +#include <linux/kernel.h> +#include <linux/types.h> +#include <asm/lowcore.h> + +void ftrace_disable_code(void); +void ftrace_call_code(void); +void ftrace_nop_code(void); + +#define FTRACE_INSN_SIZE 4 + +#ifdef CONFIG_64BIT + +asm( + " .align 4\n" + "ftrace_disable_code:\n" + " j 0f\n" + " .word 0x0024\n" + " lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n" + " basr %r14,%r1\n" + " lg %r14,8(15)\n" + " lgr %r0,%r0\n" + "0:\n"); + +asm( + " .align 4\n" + "ftrace_nop_code:\n" + " j .+"__stringify(MCOUNT_INSN_SIZE)"\n"); + +asm( + " .align 4\n" + "ftrace_call_code:\n" + " stg %r14,8(%r15)\n"); + +#else /* CONFIG_64BIT */ + +asm( + " .align 4\n" + "ftrace_disable_code:\n" + " j 0f\n" + " l %r1,"__stringify(__LC_FTRACE_FUNC)"\n" + " basr %r14,%r1\n" + " l %r14,4(%r15)\n" + " j 0f\n" + " bcr 0,%r7\n" + " bcr 0,%r7\n" + " bcr 0,%r7\n" + " bcr 0,%r7\n" + " bcr 0,%r7\n" + " bcr 0,%r7\n" + "0:\n"); + +asm( + " .align 4\n" + "ftrace_nop_code:\n" + " j .+"__stringify(MCOUNT_INSN_SIZE)"\n"); + +asm( + " .align 4\n" + "ftrace_call_code:\n" + " st %r14,4(%r15)\n"); + +#endif /* CONFIG_64BIT */ + +static int ftrace_modify_code(unsigned long ip, + void *old_code, int old_size, + void *new_code, int new_size) +{ + unsigned char replaced[MCOUNT_INSN_SIZE]; + + /* + * Note: Due to modules code can disappear and change. + * We need to protect against faulting as well as code + * changing. We do this by using the probe_kernel_* + * functions. + * This however is just a simple sanity check. + */ + if (probe_kernel_read(replaced, (void *)ip, old_size)) + return -EFAULT; + if (memcmp(replaced, old_code, old_size) != 0) + return -EINVAL; + if (probe_kernel_write((void *)ip, new_code, new_size)) + return -EPERM; + return 0; +} + +static int ftrace_make_initial_nop(struct module *mod, struct dyn_ftrace *rec, + unsigned long addr) +{ + return ftrace_modify_code(rec->ip, + ftrace_call_code, FTRACE_INSN_SIZE, + ftrace_disable_code, MCOUNT_INSN_SIZE); +} + +int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, + unsigned long addr) +{ + if (addr == MCOUNT_ADDR) + return ftrace_make_initial_nop(mod, rec, addr); + return ftrace_modify_code(rec->ip, + ftrace_call_code, FTRACE_INSN_SIZE, + ftrace_nop_code, FTRACE_INSN_SIZE); +} + +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + return ftrace_modify_code(rec->ip, + ftrace_nop_code, FTRACE_INSN_SIZE, + ftrace_call_code, FTRACE_INSN_SIZE); +} + +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + ftrace_dyn_func = (unsigned long)func; + return 0; +} + +int __init ftrace_dyn_arch_init(void *data) +{ + *(unsigned long *)data = 0; + return 0; +} |