* the dangers of modifying code on the run.
*/
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/spinlock.h>
#include <linux/hardirq.h>
#include <linux/uaccess.h>
#include <linux/init.h>
#include <linux/list.h>
+#include <trace/syscall.h>
+
#include <asm/cacheflush.h>
#include <asm/ftrace.h>
-#include <linux/ftrace.h>
#include <asm/nops.h>
#include <asm/nmi.h>
#ifdef CONFIG_DYNAMIC_FTRACE
+/*
+ * modifying_code is set to notify NMIs that they need to use
+ * memory barriers when entering or exiting. But we don't want
+ * to burden NMIs with unnecessary memory barriers when code
+ * modification is not being done (which is most of the time).
+ *
+ * A mutex is already held when ftrace_arch_code_modify_prepare
+ * and post_process are called. No locks need to be taken here.
+ *
+ * Stop machine will make sure currently running NMIs are done
+ * and new NMIs will see the updated variable before we need
+ * to worry about NMIs doing memory barriers.
+ */
+static int modifying_code __read_mostly;
+static DEFINE_PER_CPU(int, save_modifying_code);
+
int ftrace_arch_code_modify_prepare(void)
{
set_kernel_text_rw();
+ modifying_code = 1;
return 0;
}
int ftrace_arch_code_modify_post_process(void)
{
+ modifying_code = 0;
set_kernel_text_ro();
return 0;
}
void ftrace_nmi_enter(void)
{
+ __get_cpu_var(save_modifying_code) = modifying_code;
+
+ if (!__get_cpu_var(save_modifying_code))
+ return;
+
if (atomic_inc_return(&nmi_running) & MOD_CODE_WRITE_FLAG) {
smp_rmb();
ftrace_mod_code();
void ftrace_nmi_exit(void)
{
+ if (!__get_cpu_var(save_modifying_code))
+ return;
+
/* Finish all executions before clearing nmi_running */
smp_mb();
atomic_dec(&nmi_running);
nmi_wait_count++;
}
+static inline int
+within(unsigned long addr, unsigned long start, unsigned long end)
+{
+ return addr >= start && addr < end;
+}
+
static int
do_ftrace_mod_code(unsigned long ip, void *new_code)
{
+ /*
+ * On x86_64, kernel text mappings are mapped read-only with
+ * CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead
+ * of the kernel text mapping to modify the kernel text.
+ *
+ * For 32bit kernels, these mappings are same and we can use
+ * kernel identity mapping to modify code.
+ */
+ if (within(ip, (unsigned long)_text, (unsigned long)_etext))
+ ip = (unsigned long)__va(__pa(ip));
+
mod_code_ip = (void *)ip;
mod_code_newcode = new_code;
switch (faulted) {
case 0:
- pr_info("ftrace: converting mcount calls to 0f 1f 44 00 00\n");
+ pr_info("converting mcount calls to 0f 1f 44 00 00\n");
memcpy(ftrace_nop, ftrace_test_p6nop, MCOUNT_INSN_SIZE);
break;
case 1:
- pr_info("ftrace: converting mcount calls to 66 66 66 66 90\n");
+ pr_info("converting mcount calls to 66 66 66 66 90\n");
memcpy(ftrace_nop, ftrace_test_nop5, MCOUNT_INSN_SIZE);
break;
case 2:
- pr_info("ftrace: converting mcount calls to jmp . + 5\n");
+ pr_info("converting mcount calls to jmp . + 5\n");
memcpy(ftrace_nop, ftrace_test_jmp, MCOUNT_INSN_SIZE);
break;
}
* Hook the return address and push it in the stack of return addrs
* in current thread info.
*/
-void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+ unsigned long frame_pointer)
{
unsigned long old;
- unsigned long long calltime;
int faulted;
struct ftrace_graph_ent trace;
unsigned long return_hooker = (unsigned long)
&return_to_handler;
- /* Nmi's are currently unsupported */
- if (unlikely(in_nmi()))
- return;
-
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
_ASM_EXTABLE(1b, 4b)
_ASM_EXTABLE(2b, 4b)
- : [old] "=r" (old), [faulted] "=r" (faulted)
+ : [old] "=&r" (old), [faulted] "=r" (faulted)
: [parent] "r" (parent), [return_hooker] "r" (return_hooker)
: "memory"
);
return;
}
- calltime = trace_clock_local();
-
- if (ftrace_push_return_trace(old, calltime,
- self_addr, &trace.depth) == -EBUSY) {
+ if (ftrace_push_return_trace(old, self_addr, &trace.depth,
+ frame_pointer) == -EBUSY) {
*parent = old;
return;
}
}
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-
-#ifdef CONFIG_FTRACE_SYSCALLS
-
-extern unsigned long __start_syscalls_metadata[];
-extern unsigned long __stop_syscalls_metadata[];
-extern unsigned long *sys_call_table;
-
-static struct syscall_metadata **syscalls_metadata;
-
-static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
-{
- struct syscall_metadata *start;
- struct syscall_metadata *stop;
- char str[KSYM_SYMBOL_LEN];
-
-
- start = (struct syscall_metadata *)__start_syscalls_metadata;
- stop = (struct syscall_metadata *)__stop_syscalls_metadata;
- kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
-
- for ( ; start < stop; start++) {
- if (start->name && !strcmp(start->name, str))
- return start;
- }
- return NULL;
-}
-
-struct syscall_metadata *syscall_nr_to_meta(int nr)
-{
- if (!syscalls_metadata || nr >= FTRACE_SYSCALL_MAX || nr < 0)
- return NULL;
-
- return syscalls_metadata[nr];
-}
-
-void arch_init_ftrace_syscalls(void)
-{
- int i;
- struct syscall_metadata *meta;
- unsigned long **psys_syscall_table = &sys_call_table;
- static atomic_t refs;
-
- if (atomic_inc_return(&refs) != 1)
- goto end;
-
- syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
- FTRACE_SYSCALL_MAX, GFP_KERNEL);
- if (!syscalls_metadata) {
- WARN_ON(1);
- return;
- }
-
- for (i = 0; i < FTRACE_SYSCALL_MAX; i++) {
- meta = find_syscall_meta(psys_syscall_table[i]);
- syscalls_metadata[i] = meta;
- }
- return;
-
- /* Paranoid: avoid overflow */
-end:
- atomic_dec(&refs);
-}
-#endif