1 files changed, 152 insertions, 2 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d3de37299ba4..f6d9af3bf66b 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -156,6 +156,21 @@ static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
 static DEFINE_SPINLOCK(ftrace_shutdown_lock);
 static DEFINE_MUTEX(ftraced_lock);
 
+struct ftrace_page {
+        struct ftrace_page      *next;
+        int                     index;
+        struct dyn_ftrace       records[];
+} __attribute__((packed));
+
+#define ENTRIES_PER_PAGE \
+  ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
+
+/* estimate from running different kernels */
+#define NR_TO_INIT              10000
+
+static struct ftrace_page       *ftrace_pages_start;
+static struct ftrace_page       *ftrace_pages;
+
 static int ftraced_trigger;
 static int ftraced_suspend;
 
@@ -184,6 +199,21 @@ ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
         hlist_add_head(&node->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;