Have the ftrace_modify_code return error values: -EFAULT on error of reading the address -EINVAL if what is read does not match what it expected -EPERM if the write fails to update after a successful match. Signed-off-by: Steven Rostedt --- arch/x86/kernel/ftrace.c | 12 +++++++----- include/linux/ftrace.h | 24 ++++++++++++++++++++++-- kernel/trace/ftrace.c | 21 +++++++++++++++------ 3 files changed, 44 insertions(+), 13 deletions(-) Index: linux-compile.git/arch/x86/kernel/ftrace.c =================================================================== --- linux-compile.git.orig/arch/x86/kernel/ftrace.c 2008-10-22 16:30:39.000000000 -0400 +++ linux-compile.git/arch/x86/kernel/ftrace.c 2008-10-22 16:30:45.000000000 -0400 @@ -71,14 +71,16 @@ ftrace_modify_code(unsigned long ip, uns * No real locking needed, this code is run through * kstop_machine, or before SMP starts. */ - if (__copy_from_user_inatomic(replaced, (char __user *)ip, MCOUNT_INSN_SIZE)) - return 1; + if (__copy_from_user_inatomic(replaced, (char __user *)ip, + MCOUNT_INSN_SIZE)) + return -EFAULT; if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) - return 2; + return -EINVAL; - WARN_ON_ONCE(__copy_to_user_inatomic((char __user *)ip, new_code, - MCOUNT_INSN_SIZE)); + if (__copy_to_user_inatomic((char __user *)ip, new_code, + MCOUNT_INSN_SIZE)) + return -EPERM; sync_core(); Index: linux-compile.git/kernel/trace/ftrace.c =================================================================== --- linux-compile.git.orig/kernel/trace/ftrace.c 2008-10-22 16:30:39.000000000 -0400 +++ linux-compile.git/kernel/trace/ftrace.c 2008-10-22 16:30:45.000000000 -0400 @@ -591,22 +591,22 @@ ftrace_code_disable(struct dyn_ftrace *r { unsigned long ip; unsigned char *nop, *call; - int failed; + int ret; ip = rec->ip; nop = ftrace_nop_replace(); call = ftrace_call_replace(ip, mcount_addr); - failed = ftrace_modify_code(ip, call, nop); - if (failed) { - switch (failed) { - case 1: + ret = ftrace_modify_code(ip, call, nop); + if (ret) { + switch (ret) { + case -EFAULT: WARN_ON_ONCE(1); pr_info("ftrace faulted on modifying "); print_ip_sym(ip); break; - case 2: + case -EINVAL: WARN_ON_ONCE(1); pr_info("ftrace failed to modify "); print_ip_sym(ip); @@ -615,6 +615,15 @@ ftrace_code_disable(struct dyn_ftrace *r print_ip_ins(" replace: ", nop); printk(KERN_CONT "\n"); break; + case -EPERM: + WARN_ON_ONCE(1); + pr_info("ftrace faulted on writing "); + print_ip_sym(ip); + break; + default: + WARN_ON_ONCE(1); + pr_info("ftrace faulted on unknown error "); + print_ip_sym(ip); } rec->flags |= FTRACE_FL_FAILED; Index: linux-compile.git/include/linux/ftrace.h =================================================================== --- linux-compile.git.orig/include/linux/ftrace.h 2008-10-22 16:30:39.000000000 -0400 +++ linux-compile.git/include/linux/ftrace.h 2008-10-22 16:31:37.000000000 -0400 @@ -72,13 +72,33 @@ extern unsigned char *ftrace_nop_replace extern unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr); extern int ftrace_dyn_arch_init(void *data); extern int ftrace_mcount_set(unsigned long *data); -extern int ftrace_modify_code(unsigned long ip, unsigned char *old_code, - unsigned char *new_code); extern int ftrace_update_ftrace_func(ftrace_func_t func); extern void ftrace_caller(void); extern void ftrace_call(void); extern void mcount_call(void); +/** + * ftrace_modify_code - modify code segment + * @ip: the address of the code segment + * @old_code: the contents of what is expected to be there + * @new_code: the code to patch in + * + * This is a very sensitive operatation and great care needs + * to be taken by the arch. The operation should carefully + * read the location, check to see if what is read is indeed + * what we expect it to be, and then on success of the compare, + * it should write to the location. + * + * Return must be: + * 0 on success + * -EFAULT on error reading the location + * -EINVAL on a failed compare of the contents + * -EPERM on error writing to the location + * Any other value will be considered a failure. + */ +extern int ftrace_modify_code(unsigned long ip, unsigned char *old_code, + unsigned char *new_code); + extern int skip_trace(unsigned long ip); extern void ftrace_release(void *start, unsigned long size); -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/