11 files changed, 297 insertions, 39 deletions

diff --git a/Documentation/x86/efi-stub.txt b/Documentation/x86/efi-stub.txt
new file mode 100644
index 000000000000..44e6bb6ead10
--- /dev/null
+++ b/Documentation/x86/efi-stub.txt
@@ -0,0 +1,65 @@
+                          The EFI Boot Stub
+                     ---------------------------
+
+On the x86 platform, a bzImage can masquerade as a PE/COFF image,
+thereby convincing EFI firmware loaders to load it as an EFI
+executable. The code that modifies the bzImage header, along with the
+EFI-specific entry point that the firmware loader jumps to are
+collectively known as the "EFI boot stub", and live in
+arch/x86/boot/header.S and arch/x86/boot/compressed/eboot.c,
+respectively.
+
+By using the EFI boot stub it's possible to boot a Linux kernel
+without the use of a conventional EFI boot loader, such as grub or
+elilo. Since the EFI boot stub performs the jobs of a boot loader, in
+a certain sense it *IS* the boot loader.
+
+The EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option.
+
+
+**** How to install bzImage.efi
+
+The bzImage located in arch/x86/boot/bzImage must be copied to the EFI
+System Partiion (ESP) and renamed with the extension ".efi". Without
+the extension the EFI firmware loader will refuse to execute it. It's
+not possible to execute bzImage.efi from the usual Linux file systems
+because EFI firmware doesn't have support for them.
+
+
+**** Passing kernel parameters from the EFI shell
+
+Arguments to the kernel can be passed after bzImage.efi, e.g.
+
+        fs0:> bzImage.efi console=ttyS0 root=/dev/sda4
+
+
+**** The "initrd=" option
+
+Like most boot loaders, the EFI stub allows the user to specify
+multiple initrd files using the "initrd=" option. This is the only EFI
+stub-specific command line parameter, everything else is passed to the
+kernel when it boots.
+
+The path to the initrd file must be an absolute path from the
+beginning of the ESP, relative path names do not work. Also, the path
+is an EFI-style path and directory elements must be separated with
+backslashes (\). For example, given the following directory layout,
+
+fs0:>
+        Kernels\
+                        bzImage.efi
+                        initrd-large.img
+
+        Ramdisks\
+                        initrd-small.img
+                        initrd-medium.img
+
+to boot with the initrd-large.img file if the current working
+directory is fs0:\Kernels, the following command must be used,
+
+        fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img
+
+Notice how bzImage.efi can be specified with a relative path. That's
+because the image we're executing is interpreted by the EFI shell,
+which understands relative paths, whereas the rest of the command line
+is passed to bzImage.efi.
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d700811785ea..c70684f859e1 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1506,6 +1506,8 @@ config EFI_STUB
           This kernel feature allows a bzImage to be loaded directly
           by EFI firmware without the use of a bootloader.
 
+          See Documentation/x86/efi-stub.txt for more information.
+
 config SECCOMP
         def_bool y
         prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 2c14e76bb4c7..4e85f5f85837 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -16,6 +16,26 @@
 
 static efi_system_table_t *sys_table;
 
+static void efi_printk(char *str)
+{
+        char *s8;
+
+        for (s8 = str; *s8; s8++) {
+                struct efi_simple_text_output_protocol *out;
+                efi_char16_t ch[2] = { 0 };
+
+                ch[0] = *s8;
+                out = (struct efi_simple_text_output_protocol *)sys_table->con_out;
+
+                if (*s8 == '\n') {
+                        efi_char16_t nl[2] = { '\r', 0 };
+                        efi_call_phys2(out->output_string, out, nl);
+                }
+
+                efi_call_phys2(out->output_string, out, ch);
+        }
+}
+
 static efi_status_t __get_map(efi_memory_desc_t **map, unsigned long *map_size,
                               unsigned long *desc_size)
 {
@@ -531,8 +551,10 @@ static efi_status_t handle_ramdisks(efi_loaded_image_t *image,
                                 EFI_LOADER_DATA,
                                 nr_initrds * sizeof(*initrds),
                                 &initrds);
-        if (status != EFI_SUCCESS)
+        if (status != EFI_SUCCESS) {
+                efi_printk("Failed to alloc mem for initrds\n");
                 goto fail;
+        }
 
         str = (char *)(unsigned long)hdr->cmd_line_ptr;
         for (i = 0; i < nr_initrds; i++) {
@@ -575,32 +597,42 @@ static efi_status_t handle_ramdisks(efi_loaded_image_t *image,
 
                         status = efi_call_phys3(boottime->handle_protocol,
                                         image->device_handle, &fs_proto, &io);
-                        if (status != EFI_SUCCESS)
+                        if (status != EFI_SUCCESS) {
+                                efi_printk("Failed to handle fs_proto\n");
                                 goto free_initrds;
+                        }
 
                         status = efi_call_phys2(io->open_volume, io, &fh);
-                        if (status != EFI_SUCCESS)
+                        if (status != EFI_SUCCESS) {
+                                efi_printk("Failed to open volume\n");
                                 goto free_initrds;
+                        }
                 }
 
                 status = efi_call_phys5(fh->open, fh, &h, filename_16,
                                         EFI_FILE_MODE_READ, (u64)0);
-                if (status != EFI_SUCCESS)
+                if (status != EFI_SUCCESS) {
+                        efi_printk("Failed to open initrd file\n");
                         goto close_handles;
+                }
 
                 initrd->handle = h;
 
                 info_sz = 0;
                 status = efi_call_phys4(h->get_info, h, &info_guid,
                                         &info_sz, NULL);
-                if (status != EFI_BUFFER_TOO_SMALL)
+                if (status != EFI_BUFFER_TOO_SMALL) {
+                        efi_printk("Failed to get initrd info size\n");
                         goto close_handles;
+                }
 
 grow:
                 status = efi_call_phys3(sys_table->boottime->allocate_pool,
                                         EFI_LOADER_DATA, info_sz, &info);
-                if (status != EFI_SUCCESS)
+                if (status != EFI_SUCCESS) {
+                        efi_printk("Failed to alloc mem for initrd info\n");
                         goto close_handles;
+                }
 
                 status = efi_call_phys4(h->get_info, h, &info_guid,
                                         &info_sz, info);
@@ -612,8 +644,10 @@ grow:
                 file_sz = info->file_size;
                 efi_call_phys1(sys_table->boottime->free_pool, info);
 
-                if (status != EFI_SUCCESS)
+                if (status != EFI_SUCCESS) {
+                        efi_printk("Failed to get initrd info\n");
                         goto close_handles;
+                }
 
                 initrd->size = file_sz;
                 initrd_total += file_sz;
@@ -629,11 +663,14 @@ grow:
                  */
                 status = high_alloc(initrd_total, 0x1000,
                                    &initrd_addr, hdr->initrd_addr_max);
-                if (status != EFI_SUCCESS)
+                if (status != EFI_SUCCESS) {
+                        efi_printk("Failed to alloc highmem for initrds\n");
                         goto close_handles;
+                }
 
                 /* We've run out of free low memory. */
                 if (initrd_addr > hdr->initrd_addr_max) {
+                        efi_printk("We've run out of free low memory\n");
                         status = EFI_INVALID_PARAMETER;
                         goto free_initrd_total;
                 }
@@ -652,8 +689,10 @@ grow:
                                 status = efi_call_phys3(fh->read,
                                                         initrds[j].handle,
                                                         &chunksize, addr);
-                                if (status != EFI_SUCCESS)
+                                if (status != EFI_SUCCESS) {
+                                        efi_printk("Failed to read initrd\n");
                                         goto free_initrd_total;
+                                }
                                 addr += chunksize;
                                 size -= chunksize;
                         }
@@ -674,7 +713,7 @@ free_initrd_total:
         low_free(initrd_total, initrd_addr);
 
 close_handles:
-        for (k = j; k < nr_initrds; k++)
+        for (k = j; k < i; k++)
                 efi_call_phys1(fh->close, initrds[k].handle);
 free_initrds:
         efi_call_phys1(sys_table->boottime->free_pool, initrds);
@@ -732,8 +771,10 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
                         options_size++; /* NUL termination */
 
                         status = low_alloc(options_size, 1, &cmdline);
-                        if (status != EFI_SUCCESS)
+                        if (status != EFI_SUCCESS) {
+                                efi_printk("Failed to alloc mem for cmdline\n");
                                 goto fail;
+                        }
 
                         s1 = (u8 *)(unsigned long)cmdline;
                         s2 = (u16 *)options;
@@ -895,12 +936,16 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table)
 
         status = efi_call_phys3(sys_table->boottime->handle_protocol,
                                 handle, &proto, (void *)&image);
-        if (status != EFI_SUCCESS)
+        if (status != EFI_SUCCESS) {
+                efi_printk("Failed to get handle for LOADED_IMAGE_PROTOCOL\n");
                 goto fail;
+        }
 
         status = low_alloc(0x4000, 1, (unsigned long *)&boot_params);
-        if (status != EFI_SUCCESS)
+        if (status != EFI_SUCCESS) {
+                efi_printk("Failed to alloc lowmem for boot params\n");
                 goto fail;
+        }
 
         memset(boot_params, 0x0, 0x4000);
 
@@ -933,8 +978,10 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table)
         if (status != EFI_SUCCESS) {
                 status = low_alloc(hdr->init_size, hdr->kernel_alignment,
                                    &start);
-                if (status != EFI_SUCCESS)
+                if (status != EFI_SUCCESS) {
+                        efi_printk("Failed to alloc mem for kernel\n");
                         goto fail;
+                }
         }
 
         hdr->code32_start = (__u32)start;
@@ -945,19 +992,25 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table)
         status = efi_call_phys3(sys_table->boottime->allocate_pool,
                                 EFI_LOADER_DATA, sizeof(*gdt),
                                 (void **)&gdt);
-        if (status != EFI_SUCCESS)
+        if (status != EFI_SUCCESS) {
+                efi_printk("Failed to alloc mem for gdt structure\n");
                 goto fail;
+        }
 
         gdt->size = 0x800;
         status = low_alloc(gdt->size, 8, (unsigned long *)&gdt->address);
-        if (status != EFI_SUCCESS)
+        if (status != EFI_SUCCESS) {
+                efi_printk("Failed to alloc mem for gdt\n");
                 goto fail;
+        }
 
         status = efi_call_phys3(sys_table->boottime->allocate_pool,
                                 EFI_LOADER_DATA, sizeof(*idt),
                                 (void **)&idt);
-        if (status != EFI_SUCCESS)
+        if (status != EFI_SUCCESS) {
+                efi_printk("Failed to alloc mem for idt structure\n");
                 goto fail;
+        }
 
         idt->size = 0;
         idt->address = 0;
diff --git a/arch/x86/boot/compressed/eboot.h b/arch/x86/boot/compressed/eboot.h
index 39251663e65b..3b6e15627c55 100644
--- a/arch/x86/boot/compressed/eboot.h
+++ b/arch/x86/boot/compressed/eboot.h
@@ -58,4 +58,10 @@ struct efi_uga_draw_protocol {
         void *blt;
 };
 
+struct efi_simple_text_output_protocol {
+        void *reset;
+        void *output_string;
+        void *test_string;
+};
+
 #endif /* BOOT_COMPRESSED_EBOOT_H */
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 18d9005d9e4f..b0767bc08740 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -34,7 +34,7 @@
 
 #ifndef __ASSEMBLY__
 extern void mcount(void);
-extern int modifying_ftrace_code;
+extern atomic_t modifying_ftrace_code;
 
 static inline unsigned long ftrace_call_adjust(unsigned long addr)
 {
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 82f29e70d058..6b9333b429ba 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1101,14 +1101,20 @@ int is_debug_stack(unsigned long addr)
                  addr > (__get_cpu_var(debug_stack_addr) - DEBUG_STKSZ));
 }
 
+static DEFINE_PER_CPU(u32, debug_stack_use_ctr);
+
 void debug_stack_set_zero(void)
 {
+        this_cpu_inc(debug_stack_use_ctr);
         load_idt((const struct desc_ptr *)&nmi_idt_descr);
 }
 
 void debug_stack_reset(void)
 {
-        load_idt((const struct desc_ptr *)&idt_descr);
+        if (WARN_ON(!this_cpu_read(debug_stack_use_ctr)))
+                return;
+        if (this_cpu_dec_return(debug_stack_use_ctr) == 0)
+                load_idt((const struct desc_ptr *)&idt_descr);
 }
 
 #else   /* CONFIG_X86_64 */
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 320852d02026..7d65133b51be 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -191,6 +191,44 @@ ENDPROC(native_usergs_sysret64)
 .endm
 
 /*
+ * When dynamic function tracer is enabled it will add a breakpoint
+ * to all locations that it is about to modify, sync CPUs, update
+ * all the code, sync CPUs, then remove the breakpoints. In this time
+ * if lockdep is enabled, it might jump back into the debug handler
+ * outside the updating of the IST protection. (TRACE_IRQS_ON/OFF).
+ *
+ * We need to change the IDT table before calling TRACE_IRQS_ON/OFF to
+ * make sure the stack pointer does not get reset back to the top
+ * of the debug stack, and instead just reuses the current stack.
+ */
+#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_TRACE_IRQFLAGS)
+
+.macro TRACE_IRQS_OFF_DEBUG
+        call debug_stack_set_zero
+        TRACE_IRQS_OFF
+        call debug_stack_reset
+.endm
+
+.macro TRACE_IRQS_ON_DEBUG
+        call debug_stack_set_zero
+        TRACE_IRQS_ON
+        call debug_stack_reset
+.endm
+
+.macro TRACE_IRQS_IRETQ_DEBUG offset=ARGOFFSET
+        bt   $9,EFLAGS-\offset(%rsp)    /* interrupts off? */
+        jnc  1f
+        TRACE_IRQS_ON_DEBUG
+1:
+.endm
+
+#else
+# define TRACE_IRQS_OFF_DEBUG           TRACE_IRQS_OFF
+# define TRACE_IRQS_ON_DEBUG            TRACE_IRQS_ON
+# define TRACE_IRQS_IRETQ_DEBUG         TRACE_IRQS_IRETQ
+#endif
+
+/*
  * C code is not supposed to know about undefined top of stack. Every time
  * a C function with an pt_regs argument is called from the SYSCALL based
  * fast path FIXUP_TOP_OF_STACK is needed.
@@ -1098,7 +1136,7 @@ ENTRY(\sym)
         subq $ORIG_RAX-R15, %rsp
         CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
         call save_paranoid
-        TRACE_IRQS_OFF
+        TRACE_IRQS_OFF_DEBUG
         movq %rsp,%rdi          /* pt_regs pointer */
         xorl %esi,%esi          /* no error code */
         subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
@@ -1393,7 +1431,7 @@ paranoidzeroentry machine_check *machine_check_vector(%rip)
 ENTRY(paranoid_exit)
         DEFAULT_FRAME
         DISABLE_INTERRUPTS(CLBR_NONE)
-        TRACE_IRQS_OFF
+        TRACE_IRQS_OFF_DEBUG
         testl %ebx,%ebx                         /* swapgs needed? */
         jnz paranoid_restore
         testl $3,CS(%rsp)
@@ -1404,7 +1442,7 @@ paranoid_swapgs:
         RESTORE_ALL 8
         jmp irq_return
 paranoid_restore:
-        TRACE_IRQS_IRETQ 0
+        TRACE_IRQS_IRETQ_DEBUG 0
         RESTORE_ALL 8
         jmp irq_return
 paranoid_userspace:
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 32ff36596ab1..c3a7cb4bf6e6 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -100,7 +100,7 @@ static const unsigned char *ftrace_nop_replace(void)
 }
 
 static int
-ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
+ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
                    unsigned const char *new_code)
 {
         unsigned char replaced[MCOUNT_INSN_SIZE];
@@ -141,7 +141,20 @@ int ftrace_make_nop(struct module *mod,
         old = ftrace_call_replace(ip, addr);
         new = ftrace_nop_replace();
 
-        return ftrace_modify_code(rec->ip, old, new);
+        /*
+         * On boot up, and when modules are loaded, the MCOUNT_ADDR
+         * is converted to a nop, and will never become MCOUNT_ADDR
+         * again. This code is either running before SMP (on boot up)
+         * or before the code will ever be executed (module load).
+         * We do not want to use the breakpoint version in this case,
+         * just modify the code directly.
+         */
+        if (addr == MCOUNT_ADDR)
+                return ftrace_modify_code_direct(rec->ip, old, new);
+
+        /* Normal cases use add_brk_on_nop */
+        WARN_ONCE(1, "invalid use of ftrace_make_nop");
+        return -EINVAL;
 }
 
 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
@@ -152,9 +165,47 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
         old = ftrace_nop_replace();
         new = ftrace_call_replace(ip, addr);
 
-        return ftrace_modify_code(rec->ip, old, new);
+        /* Should only be called when module is loaded */
+        return ftrace_modify_code_direct(rec->ip, old, new);
 }
 
+/*
+ * The modifying_ftrace_code is used to tell the breakpoint
+ * handler to call ftrace_int3_handler(). If it fails to
+ * call this handler for a breakpoint added by ftrace, then
+ * the kernel may crash.
+ *
+ * As atomic_writes on x86 do not need a barrier, we do not
+ * need to add smp_mb()s for this to work. It is also considered
+ * that we can not read the modifying_ftrace_code before
+ * executing the breakpoint. That would be quite remarkable if
+ * it could do that. Here's the flow that is required:
+ *
+ *   CPU-0                          CPU-1
+ *
+ * atomic_inc(mfc);
+ * write int3s
+ *                              <trap-int3> // implicit (r)mb
+ *                              if (atomic_read(mfc))
+ *                                      call ftrace_int3_handler()
+ *
+ * Then when we are finished:
+ *
+ * atomic_dec(mfc);
+ *
+ * If we hit a breakpoint that was not set by ftrace, it does not
+ * matter if ftrace_int3_handler() is called or not. It will
+ * simply be ignored. But it is crucial that a ftrace nop/caller
+ * breakpoint is handled. No other user should ever place a
+ * breakpoint on an ftrace nop/caller location. It must only
+ * be done by this code.
+ */
+atomic_t modifying_ftrace_code __read_mostly;
+
+static int
+ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
+                   unsigned const char *new_code);
+
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
         unsigned long ip = (unsigned long)(&ftrace_call);
@@ -163,13 +214,17 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 
         memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
         new = ftrace_call_replace(ip, (unsigned long)func);
+
+        /* See comment above by declaration of modifying_ftrace_code */
+        atomic_inc(&modifying_ftrace_code);
+
         ret = ftrace_modify_code(ip, old, new);
 
+        atomic_dec(&modifying_ftrace_code);
+
         return ret;
 }
 
-int modifying_ftrace_code __read_mostly;
-
 /*
  * A breakpoint was added to the code address we are about to
  * modify, and this is the handle that will just skip over it.
@@ -489,13 +544,46 @@ void ftrace_replace_code(int enable)
         }
 }
 
+static int
+ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
+                   unsigned const char *new_code)
+{
+        int ret;
+
+        ret = add_break(ip, old_code);
+        if (ret)
+                goto out;
+
+        run_sync();
+
+        ret = add_update_code(ip, new_code);
+        if (ret)
+                goto fail_update;
+
+        run_sync();
+
+        ret = ftrace_write(ip, new_code, 1);
+        if (ret) {
+                ret = -EPERM;
+                goto out;
+        }
+        run_sync();
+ out:
+        return ret;
+
+ fail_update:
+        probe_kernel_write((void *)ip, &old_code[0], 1);
+        goto out;
+}
+
 void arch_ftrace_update_code(int command)
 {
-        modifying_ftrace_code++;
+        /* See comment above by declaration of modifying_ftrace_code */
+        atomic_inc(&modifying_ftrace_code);
 
         ftrace_modify_all_code(command);
 
-        modifying_ftrace_code--;
+        atomic_dec(&modifying_ftrace_code);
 }
 
 int __init ftrace_dyn_arch_init(void *data)
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 90875279ef3d..a0b2f84457be 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -444,14 +444,16 @@ static inline void nmi_nesting_preprocess(struct pt_regs *regs)
          */
         if (unlikely(is_debug_stack(regs->sp))) {
                 debug_stack_set_zero();
-                __get_cpu_var(update_debug_stack) = 1;
+                this_cpu_write(update_debug_stack, 1);
         }
 }
 
 static inline void nmi_nesting_postprocess(void)
 {
-        if (unlikely(__get_cpu_var(update_debug_stack)))
+        if (unlikely(this_cpu_read(update_debug_stack))) {
                 debug_stack_reset();
+                this_cpu_write(update_debug_stack, 0);
+        }
 }
 #endif
 
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 13b1990c7c58..c4c6a5c2bf0f 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1211,12 +1211,6 @@ static long x32_arch_ptrace(struct task_struct *child,
                                              0, sizeof(struct user_i387_struct),
                                              datap);
 
-                /* normal 64bit interface to access TLS data.
-                   Works just like arch_prctl, except that the arguments
-                   are reversed. */
-        case PTRACE_ARCH_PRCTL:
-                return do_arch_prctl(child, data, addr);
-
         default:
                 return compat_ptrace_request(child, request, addr, data);
         }
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index ff08457a025d..05b31d92f69c 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -303,8 +303,12 @@ gp_in_kernel:
 dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code)
 {
 #ifdef CONFIG_DYNAMIC_FTRACE
-        /* ftrace must be first, everything else may cause a recursive crash */
-        if (unlikely(modifying_ftrace_code) && ftrace_int3_handler(regs))
+        /*
+         * ftrace must be first, everything else may cause a recursive crash.
+         * See note by declaration of modifying_ftrace_code in ftrace.c
+         */
+        if (unlikely(atomic_read(&modifying_ftrace_code)) &&
+            ftrace_int3_handler(regs))
                 return;
 #endif
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP