diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 2e060c58b860f4fa1a1b051c8e7b09a7a23abd38..b69795efa2264008a7d168b564e2e9d173606d2d 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -23,25 +23,6 @@ /* Long is fine, even if it is only 4 bytes ;-) */ static long *ftrace_nop; -struct ftrace_record { - struct dyn_ftrace rec; - int failed; -} __attribute__((packed)); - -struct ftrace_page { - struct ftrace_page *next; - int index; - struct ftrace_record records[]; -} __attribute__((packed)); - -#define ENTRIES_PER_PAGE \ - ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct ftrace_record)) - -/* estimate from running different kernels */ -#define NR_TO_INIT 10000 - -#define MCOUNT_ADDR ((long)(&mcount)) - union ftrace_code_union { char code[5]; struct { @@ -50,33 +31,41 @@ union ftrace_code_union { } __attribute__((packed)); }; -static struct ftrace_page *ftrace_pages_start; -static struct ftrace_page *ftrace_pages; - -notrace struct dyn_ftrace *ftrace_alloc_shutdown_node(unsigned long ip) +notrace int ftrace_ip_converted(unsigned long ip) { - struct ftrace_record *rec; unsigned long save; ip -= CALL_BACK; save = *(long *)ip; - /* If this was already converted, skip it */ - if (save == *ftrace_nop) - return NULL; + return save == *ftrace_nop; +} - if (ftrace_pages->index == ENTRIES_PER_PAGE) { - if (!ftrace_pages->next) - return NULL; - ftrace_pages = ftrace_pages->next; - } +static int notrace ftrace_calc_offset(long ip, long addr) +{ + return (int)(addr - ip); +} - rec = &ftrace_pages->records[ftrace_pages->index++]; +notrace unsigned char *ftrace_nop_replace(void) +{ + return (char *)ftrace_nop; +} + +notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) +{ + static union ftrace_code_union calc; - return &rec->rec; + calc.e8 = 0xe8; + calc.offset = ftrace_calc_offset(ip, addr); + + /* + * No locking needed, this must be called via kstop_machine + * which in essence is like running on a uniprocessor machine. + */ + return calc.code; } -static int notrace +notrace int ftrace_modify_code(unsigned long ip, unsigned char *old_code, unsigned char *new_code) { @@ -86,6 +75,9 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code, unsigned char newch = new_code[4]; int faulted = 0; + /* move the IP back to the start of the call */ + ip -= CALL_BACK; + /* * Note: Due to modules and __init, code can * disappear and change, we need to protect against faulting @@ -117,129 +109,12 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code, return faulted; } -static int notrace ftrace_calc_offset(long ip) -{ - return (int)(MCOUNT_ADDR - ip); -} - -notrace void ftrace_code_disable(struct dyn_ftrace *rec) -{ - unsigned long ip; - union ftrace_code_union save; - struct ftrace_record *r = - container_of(rec, struct ftrace_record, rec); - - ip = rec->ip; - - save.e8 = 0xe8; - save.offset = ftrace_calc_offset(ip); - - /* move the IP back to the start of the call */ - ip -= CALL_BACK; - - r->failed = ftrace_modify_code(ip, save.code, (char *)ftrace_nop); -} - -static void notrace ftrace_replace_code(int saved) -{ - unsigned char *new = NULL, *old = NULL; - struct ftrace_record *rec; - struct ftrace_page *pg; - unsigned long ip; - int i; - - if (saved) - old = (char *)ftrace_nop; - else - new = (char *)ftrace_nop; - - for (pg = ftrace_pages_start; pg; pg = pg->next) { - for (i = 0; i < pg->index; i++) { - union ftrace_code_union calc; - rec = &pg->records[i]; - - /* don't modify code that has already faulted */ - if (rec->failed) - continue; - - ip = rec->rec.ip; - - calc.e8 = 0xe8; - calc.offset = ftrace_calc_offset(ip); - - if (saved) - new = calc.code; - else - old = calc.code; - - ip -= CALL_BACK; - - rec->failed = ftrace_modify_code(ip, old, new); - } - } - -} - -notrace void ftrace_startup_code(void) -{ - ftrace_replace_code(1); -} - -notrace void ftrace_shutdown_code(void) -{ - ftrace_replace_code(0); -} - -notrace void ftrace_shutdown_replenish(void) -{ - if (ftrace_pages->next) - return; - - /* allocate another page */ - ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL); -} - -notrace int __init ftrace_shutdown_arch_init(void) +int __init ftrace_dyn_arch_init(void) { const unsigned char *const *noptable = find_nop_table(); - struct ftrace_page *pg; - int cnt; - int i; ftrace_nop = (unsigned long *)noptable[CALL_BACK]; - /* allocate a few pages */ - ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL); - if (!ftrace_pages_start) - return -1; - - /* - * Allocate a few more pages. - * - * TODO: have some parser search vmlinux before - * final linking to find all calls to ftrace. - * Then we can: - * a) know how many pages to allocate. - * and/or - * b) set up the table then. - * - * The dynamic code is still necessary for - * modules. - */ - - pg = ftrace_pages = ftrace_pages_start; - - cnt = NR_TO_INIT / ENTRIES_PER_PAGE; - - for (i = 0; i < cnt; i++) { - pg->next = (void *)get_zeroed_page(GFP_KERNEL); - - /* If we fail, we'll try later anyway */ - if (!pg->next) - break; - - pg = pg->next; - } - return 0; } + diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index ccd8537dbdb76003f96098c96714c1ac579304a3..d509ad6c9cb82413ffbe4302e2177bd9e98d728c 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -42,19 +42,23 @@ extern void mcount(void); # define FTRACE_HASHBITS 10 # define FTRACE_HASHSIZE (1<node, &ftrace_hash[key]); } +static notrace struct dyn_ftrace *ftrace_alloc_shutdown_node(unsigned long ip) +{ + /* If this was already converted, skip it */ + if (ftrace_ip_converted(ip)) + return NULL; + + if (ftrace_pages->index == ENTRIES_PER_PAGE) { + if (!ftrace_pages->next) + return NULL; + ftrace_pages = ftrace_pages->next; + } + + return &ftrace_pages->records[ftrace_pages->index++]; +} + static void notrace ftrace_record_ip(unsigned long ip, unsigned long parent_ip) { @@ -252,6 +282,62 @@ static struct ftrace_ops ftrace_shutdown_ops __read_mostly = .func = ftrace_record_ip, }; +#define MCOUNT_ADDR ((long)(&mcount)) + +static void notrace ftrace_replace_code(int saved) +{ + unsigned char *new = NULL, *old = NULL; + struct dyn_ftrace *rec; + struct ftrace_page *pg; + unsigned long ip; + int failed; + int i; + + if (saved) + old = ftrace_nop_replace(); + else + new = ftrace_nop_replace(); + + for (pg = ftrace_pages_start; pg; pg = pg->next) { + for (i = 0; i < pg->index; i++) { + rec = &pg->records[i]; + + /* don't modify code that has already faulted */ + if (rec->flags & FTRACE_FL_FAILED) + continue; + + ip = rec->ip; + + if (saved) + new = ftrace_call_replace(ip, MCOUNT_ADDR); + else + old = ftrace_call_replace(ip, MCOUNT_ADDR); + + failed = ftrace_modify_code(ip, old, new); + if (failed) + rec->flags |= FTRACE_FL_FAILED; + } + } +} + +static notrace void ftrace_startup_code(void) +{ + ftrace_replace_code(1); +} + +static notrace void ftrace_shutdown_code(void) +{ + ftrace_replace_code(0); +} + +static notrace void ftrace_shutdown_replenish(void) +{ + if (ftrace_pages->next) + return; + + /* allocate another page */ + ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL); +} static int notrace __ftrace_modify_code(void *data) { @@ -261,6 +347,23 @@ static int notrace __ftrace_modify_code(void *data) return 0; } +static notrace void +ftrace_code_disable(struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long ip; + unsigned char *nop, *call; + int failed; + + ip = rec->ip; + + nop = ftrace_nop_replace(); + call = ftrace_call_replace(ip, addr); + + failed = ftrace_modify_code(ip, call, nop); + if (failed) + rec->flags |= FTRACE_FL_FAILED; +} + static void notrace ftrace_run_startup_code(void) { stop_machine_run(__ftrace_modify_code, ftrace_startup_code, NR_CPUS); @@ -346,7 +449,7 @@ static int notrace __ftrace_update_code(void *ignore) /* all CPUS are stopped, we are safe to modify code */ hlist_for_each_entry(p, t, &head, node) { - ftrace_code_disable(p); + ftrace_code_disable(p, MCOUNT_ADDR); ftrace_update_cnt++; } @@ -407,12 +510,59 @@ static int notrace ftraced(void *ignore) return 0; } +static int __init ftrace_dyn_table_alloc(void) +{ + struct ftrace_page *pg; + int cnt; + int i; + int ret; + + ret = ftrace_dyn_arch_init(); + if (ret) + return ret; + + /* allocate a few pages */ + ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL); + if (!ftrace_pages_start) + return -1; + + /* + * Allocate a few more pages. + * + * TODO: have some parser search vmlinux before + * final linking to find all calls to ftrace. + * Then we can: + * a) know how many pages to allocate. + * and/or + * b) set up the table then. + * + * The dynamic code is still necessary for + * modules. + */ + + pg = ftrace_pages = ftrace_pages_start; + + cnt = NR_TO_INIT / ENTRIES_PER_PAGE; + + for (i = 0; i < cnt; i++) { + pg->next = (void *)get_zeroed_page(GFP_KERNEL); + + /* If we fail, we'll try later anyway */ + if (!pg->next) + break; + + pg = pg->next; + } + + return 0; +} + static int __init notrace ftrace_shutdown_init(void) { struct task_struct *p; int ret; - ret = ftrace_shutdown_arch_init(); + ret = ftrace_dyn_table_alloc(); if (ret) return ret;