#include <linux/spinlock.h>
#include <linux/hardirq.h>
+#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/percpu.h>
+#include <linux/sched.h>
#include <linux/init.h>
#include <linux/list.h>
-#include <asm/alternative.h>
+#include <trace/syscall.h>
-#define CALL_BACK 5
+#include <asm/cacheflush.h>
+#include <asm/ftrace.h>
+#include <asm/nops.h>
+#include <asm/nmi.h>
-/* Long is fine, even if it is only 4 bytes ;-) */
-static long *ftrace_nop;
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+int ftrace_arch_code_modify_prepare(void)
+{
+ set_kernel_text_rw();
+ return 0;
+}
+
+int ftrace_arch_code_modify_post_process(void)
+{
+ set_kernel_text_ro();
+ return 0;
+}
union ftrace_code_union {
- char code[5];
+ char code[MCOUNT_INSN_SIZE];
struct {
char e8;
int offset;
} __attribute__((packed));
};
-static int notrace ftrace_calc_offset(long ip, long addr)
+static int ftrace_calc_offset(long ip, long addr)
{
return (int)(addr - ip);
}
-notrace unsigned char *ftrace_nop_replace(void)
-{
- return (char *)ftrace_nop;
-}
-
-notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
{
static union ftrace_code_union calc;
calc.e8 = 0xe8;
- calc.offset = ftrace_calc_offset(ip, addr);
+ calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
/*
* No locking needed, this must be called via kstop_machine
return calc.code;
}
-notrace int
+/*
+ * Modifying code must take extra care. On an SMP machine, if
+ * the code being modified is also being executed on another CPU
+ * that CPU will have undefined results and possibly take a GPF.
+ * We use kstop_machine to stop other CPUS from exectuing code.
+ * But this does not stop NMIs from happening. We still need
+ * to protect against that. We separate out the modification of
+ * the code to take care of this.
+ *
+ * Two buffers are added: An IP buffer and a "code" buffer.
+ *
+ * 1) Put the instruction pointer into the IP buffer
+ * and the new code into the "code" buffer.
+ * 2) Wait for any running NMIs to finish and set a flag that says
+ * we are modifying code, it is done in an atomic operation.
+ * 3) Write the code
+ * 4) clear the flag.
+ * 5) Wait for any running NMIs to finish.
+ *
+ * If an NMI is executed, the first thing it does is to call
+ * "ftrace_nmi_enter". This will check if the flag is set to write
+ * and if it is, it will write what is in the IP and "code" buffers.
+ *
+ * The trick is, it does not matter if everyone is writing the same
+ * content to the code location. Also, if a CPU is executing code
+ * it is OK to write to that code location if the contents being written
+ * are the same as what exists.
+ */
+
+#define MOD_CODE_WRITE_FLAG (1 << 31) /* set when NMI should do the write */
+static atomic_t nmi_running = ATOMIC_INIT(0);
+static int mod_code_status; /* holds return value of text write */
+static void *mod_code_ip; /* holds the IP to write to */
+static void *mod_code_newcode; /* holds the text to write to the IP */
+
+static unsigned nmi_wait_count;
+static atomic_t nmi_update_count = ATOMIC_INIT(0);
+
+int ftrace_arch_read_dyn_info(char *buf, int size)
+{
+ int r;
+
+ r = snprintf(buf, size, "%u %u",
+ nmi_wait_count,
+ atomic_read(&nmi_update_count));
+ return r;
+}
+
+static void clear_mod_flag(void)
+{
+ int old = atomic_read(&nmi_running);
+
+ for (;;) {
+ int new = old & ~MOD_CODE_WRITE_FLAG;
+
+ if (old == new)
+ break;
+
+ old = atomic_cmpxchg(&nmi_running, old, new);
+ }
+}
+
+static void ftrace_mod_code(void)
+{
+ /*
+ * Yes, more than one CPU process can be writing to mod_code_status.
+ * (and the code itself)
+ * But if one were to fail, then they all should, and if one were
+ * to succeed, then they all should.
+ */
+ mod_code_status = probe_kernel_write(mod_code_ip, mod_code_newcode,
+ MCOUNT_INSN_SIZE);
+
+ /* if we fail, then kill any new writers */
+ if (mod_code_status)
+ clear_mod_flag();
+}
+
+void ftrace_nmi_enter(void)
+{
+ if (atomic_inc_return(&nmi_running) & MOD_CODE_WRITE_FLAG) {
+ smp_rmb();
+ ftrace_mod_code();
+ atomic_inc(&nmi_update_count);
+ }
+ /* Must have previous changes seen before executions */
+ smp_mb();
+}
+
+void ftrace_nmi_exit(void)
+{
+ /* Finish all executions before clearing nmi_running */
+ smp_mb();
+ atomic_dec(&nmi_running);
+}
+
+static void wait_for_nmi_and_set_mod_flag(void)
+{
+ if (!atomic_cmpxchg(&nmi_running, 0, MOD_CODE_WRITE_FLAG))
+ return;
+
+ do {
+ cpu_relax();
+ } while (atomic_cmpxchg(&nmi_running, 0, MOD_CODE_WRITE_FLAG));
+
+ nmi_wait_count++;
+}
+
+static void wait_for_nmi(void)
+{
+ if (!atomic_read(&nmi_running))
+ return;
+
+ do {
+ cpu_relax();
+ } while (atomic_read(&nmi_running));
+
+ nmi_wait_count++;
+}
+
+static int
+do_ftrace_mod_code(unsigned long ip, void *new_code)
+{
+ mod_code_ip = (void *)ip;
+ mod_code_newcode = new_code;
+
+ /* The buffers need to be visible before we let NMIs write them */
+ smp_mb();
+
+ wait_for_nmi_and_set_mod_flag();
+
+ /* Make sure all running NMIs have finished before we write the code */
+ smp_mb();
+
+ ftrace_mod_code();
+
+ /* Make sure the write happens before clearing the bit */
+ smp_mb();
+
+ clear_mod_flag();
+ wait_for_nmi();
+
+ return mod_code_status;
+}
+
+
+
+
+static unsigned char ftrace_nop[MCOUNT_INSN_SIZE];
+
+static unsigned char *ftrace_nop_replace(void)
+{
+ return ftrace_nop;
+}
+
+static int
ftrace_modify_code(unsigned long ip, unsigned char *old_code,
unsigned char *new_code)
{
- unsigned replaced;
- unsigned old = *(unsigned *)old_code; /* 4 bytes */
- unsigned new = *(unsigned *)new_code; /* 4 bytes */
- unsigned char newch = new_code[4];
- int faulted = 0;
-
- /* move the IP back to the start of the call */
- ip -= CALL_BACK;
+ unsigned char replaced[MCOUNT_INSN_SIZE];
/*
* Note: Due to modules and __init, code can
* disappear and change, we need to protect against faulting
- * as well as code changing.
+ * as well as code changing. We do this by using the
+ * probe_kernel_* functions.
*
* No real locking needed, this code is run through
- * kstop_machine.
+ * kstop_machine, or before SMP starts.
*/
- asm volatile (
- "1: lock\n"
- " cmpxchg %3, (%2)\n"
- " jnz 2f\n"
- " movb %b4, 4(%2)\n"
- "2:\n"
- ".section .fixup, \"ax\"\n"
- "3: movl $1, %0\n"
- " jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b)
- : "=r"(faulted), "=a"(replaced)
- : "r"(ip), "r"(new), "c"(newch),
- "0"(faulted), "a"(old)
- : "memory");
+
+ /* read the text we want to modify */
+ if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+ return -EFAULT;
+
+ /* Make sure it is what we expect it to be */
+ if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+ return -EINVAL;
+
+ /* replace the text with the new text */
+ if (do_ftrace_mod_code(ip, new_code))
+ return -EPERM;
+
sync_core();
- if (replaced != old && replaced != new)
- faulted = 2;
+ return 0;
+}
+
+int ftrace_make_nop(struct module *mod,
+ struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned char *new, *old;
+ unsigned long ip = rec->ip;
+
+ old = ftrace_call_replace(ip, addr);
+ new = ftrace_nop_replace();
- return faulted;
+ return ftrace_modify_code(rec->ip, old, new);
}
-notrace int ftrace_update_ftrace_func(ftrace_func_t func)
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned char *new, *old;
+ unsigned long ip = rec->ip;
+
+ old = ftrace_nop_replace();
+ new = ftrace_call_replace(ip, addr);
+
+ return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
- unsigned char old[5], *new;
+ unsigned char old[MCOUNT_INSN_SIZE], *new;
int ret;
- ip += CALL_BACK;
-
- memcpy(old, &ftrace_call, 5);
+ memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
new = ftrace_call_replace(ip, (unsigned long)func);
ret = ftrace_modify_code(ip, old, new);
return ret;
}
-notrace int ftrace_mcount_set(unsigned long *data)
+int __init ftrace_dyn_arch_init(void *data)
{
- unsigned long ip = (long)(&mcount_call);
- unsigned long *addr = data;
- unsigned char old[5], *new;
-
- /* ip is at the location, but modify code will subtact this */
- ip += CALL_BACK;
+ extern const unsigned char ftrace_test_p6nop[];
+ extern const unsigned char ftrace_test_nop5[];
+ extern const unsigned char ftrace_test_jmp[];
+ int faulted = 0;
/*
- * Replace the mcount stub with a pointer to the
- * ip recorder function.
+ * There is no good nop for all x86 archs.
+ * We will default to using the P6_NOP5, but first we
+ * will test to make sure that the nop will actually
+ * work on this CPU. If it faults, we will then
+ * go to a lesser efficient 5 byte nop. If that fails
+ * we then just use a jmp as our nop. This isn't the most
+ * efficient nop, but we can not use a multi part nop
+ * since we would then risk being preempted in the middle
+ * of that nop, and if we enabled tracing then, it might
+ * cause a system crash.
+ *
+ * TODO: check the cpuid to determine the best nop.
*/
- memcpy(old, &mcount_call, 5);
- new = ftrace_call_replace(ip, *addr);
- *addr = ftrace_modify_code(ip, old, new);
+ asm volatile (
+ "ftrace_test_jmp:"
+ "jmp ftrace_test_p6nop\n"
+ "nop\n"
+ "nop\n"
+ "nop\n" /* 2 byte jmp + 3 bytes */
+ "ftrace_test_p6nop:"
+ P6_NOP5
+ "jmp 1f\n"
+ "ftrace_test_nop5:"
+ ".byte 0x66,0x66,0x66,0x66,0x90\n"
+ "1:"
+ ".section .fixup, \"ax\"\n"
+ "2: movl $1, %0\n"
+ " jmp ftrace_test_nop5\n"
+ "3: movl $2, %0\n"
+ " jmp 1b\n"
+ ".previous\n"
+ _ASM_EXTABLE(ftrace_test_p6nop, 2b)
+ _ASM_EXTABLE(ftrace_test_nop5, 3b)
+ : "=r"(faulted) : "0" (faulted));
+
+ switch (faulted) {
+ case 0:
+ pr_info("ftrace: 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");
+ memcpy(ftrace_nop, ftrace_test_nop5, MCOUNT_INSN_SIZE);
+ break;
+ case 2:
+ pr_info("ftrace: converting mcount calls to jmp . + 5\n");
+ memcpy(ftrace_nop, ftrace_test_jmp, MCOUNT_INSN_SIZE);
+ break;
+ }
+
+ /* The return code is retured via data */
+ *(unsigned long *)data = 0;
return 0;
}
+#endif
-int __init ftrace_dyn_arch_init(void *data)
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern void ftrace_graph_call(void);
+
+static int ftrace_mod_jmp(unsigned long ip,
+ int old_offset, int new_offset)
{
- const unsigned char *const *noptable = find_nop_table();
+ unsigned char code[MCOUNT_INSN_SIZE];
+
+ if (probe_kernel_read(code, (void *)ip, MCOUNT_INSN_SIZE))
+ return -EFAULT;
- /* This is running in kstop_machine */
+ if (code[0] != 0xe9 || old_offset != *(int *)(&code[1]))
+ return -EINVAL;
- ftrace_mcount_set(data);
+ *(int *)(&code[1]) = new_offset;
- ftrace_nop = (unsigned long *)noptable[CALL_BACK];
+ if (do_ftrace_mod_code(ip, &code))
+ return -EPERM;
return 0;
}
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ unsigned long ip = (unsigned long)(&ftrace_graph_call);
+ int old_offset, new_offset;
+
+ old_offset = (unsigned long)(&ftrace_stub) - (ip + MCOUNT_INSN_SIZE);
+ new_offset = (unsigned long)(&ftrace_graph_caller) - (ip + MCOUNT_INSN_SIZE);
+
+ return ftrace_mod_jmp(ip, old_offset, new_offset);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ unsigned long ip = (unsigned long)(&ftrace_graph_call);
+ int old_offset, new_offset;
+
+ old_offset = (unsigned long)(&ftrace_graph_caller) - (ip + MCOUNT_INSN_SIZE);
+ new_offset = (unsigned long)(&ftrace_stub) - (ip + MCOUNT_INSN_SIZE);
+
+ return ftrace_mod_jmp(ip, old_offset, new_offset);
+}
+
+#endif /* !CONFIG_DYNAMIC_FTRACE */
+
+/*
+ * 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,
+ unsigned long frame_pointer)
+{
+ unsigned long old;
+ 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;
+
+ /*
+ * Protect against fault, even if it shouldn't
+ * happen. This tool is too much intrusive to
+ * ignore such a protection.
+ */
+ asm volatile(
+ "1: " _ASM_MOV " (%[parent]), %[old]\n"
+ "2: " _ASM_MOV " %[return_hooker], (%[parent])\n"
+ " movl $0, %[faulted]\n"
+ "3:\n"
+
+ ".section .fixup, \"ax\"\n"
+ "4: movl $1, %[faulted]\n"
+ " jmp 3b\n"
+ ".previous\n"
+
+ _ASM_EXTABLE(1b, 4b)
+ _ASM_EXTABLE(2b, 4b)
+
+ : [old] "=&r" (old), [faulted] "=r" (faulted)
+ : [parent] "r" (parent), [return_hooker] "r" (return_hooker)
+ : "memory"
+ );
+
+ if (unlikely(faulted)) {
+ ftrace_graph_stop();
+ WARN_ON(1);
+ return;
+ }
+
+ if (ftrace_push_return_trace(old, self_addr, &trace.depth,
+ frame_pointer) == -EBUSY) {
+ *parent = old;
+ return;
+ }
+
+ trace.func = self_addr;
+
+ /* Only trace if the calling function expects to */
+ if (!ftrace_graph_entry(&trace)) {
+ current->curr_ret_stack--;
+ *parent = old;
+ }
+}
+#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
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff