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Subject[PATCH v2 03/31] arm64: Exception handling
Date
The patch contains the exception entry code (kernel/entry.S), pt_regs
structure and related accessors, undefined instruction trapping and
stack tracing.

AArch64 Linux kernel (including kernel threads) runs in EL1 mode using
the SP1 stack. The vectors don't have a fixed address, only alignment
(2^11) requirements.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/include/asm/ptrace.h | 206 +++++++++++
arch/arm64/include/asm/stacktrace.h | 29 ++
arch/arm64/include/asm/traps.h | 30 ++
arch/arm64/kernel/entry.S | 695 +++++++++++++++++++++++++++++++++++
arch/arm64/kernel/stacktrace.c | 127 +++++++
arch/arm64/kernel/traps.c | 357 ++++++++++++++++++
6 files changed, 1444 insertions(+), 0 deletions(-)
create mode 100644 arch/arm64/include/asm/ptrace.h
create mode 100644 arch/arm64/include/asm/stacktrace.h
create mode 100644 arch/arm64/include/asm/traps.h
create mode 100644 arch/arm64/kernel/entry.S
create mode 100644 arch/arm64/kernel/stacktrace.c
create mode 100644 arch/arm64/kernel/traps.c

diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
new file mode 100644
index 0000000..a9abace
--- /dev/null
+++ b/arch/arm64/include/asm/ptrace.h
@@ -0,0 +1,206 @@
+/*
+ * Based on arch/arm/include/asm/ptrace.h
+ *
+ * Copyright (C) 1996-2003 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_PTRACE_H
+#define __ASM_PTRACE_H
+
+#include <linux/types.h>
+
+#include <asm/hwcap.h>
+
+#define PTRACE_GETREGS 12
+#define PTRACE_SETREGS 13
+#define PTRACE_GETFPSIMDREGS 14
+#define PTRACE_SETFPSIMDREGS 15
+/* PTRACE_ATTACH is 16 */
+/* PTRACE_DETACH is 17 */
+#define PTRACE_GET_THREAD_AREA 22
+#define PTRACE_SET_SYSCALL 23
+#define PTRACE_GETHBPREGS 29
+#define PTRACE_SETHBPREGS 30
+
+/* AArch32-specific ptrace requests */
+#define COMPAT_PTRACE_GETVFPREGS 27
+#define COMPAT_PTRACE_SETVFPREGS 28
+
+/*
+ * PSR bits
+ */
+#define PSR_MODE_EL0t 0x00000000
+#define PSR_MODE_EL1t 0x00000004
+#define PSR_MODE_EL1h 0x00000005
+#define PSR_MODE_EL2t 0x00000008
+#define PSR_MODE_EL2h 0x00000009
+#define PSR_MODE_EL3t 0x0000000c
+#define PSR_MODE_EL3h 0x0000000d
+#define PSR_MODE_MASK 0x0000000f
+
+/* AArch32 CPSR bits */
+#define PSR_MODE32_BIT 0x00000010
+#define COMPAT_PSR_MODE_USR 0x00000010
+#define COMPAT_PSR_T_BIT 0x00000020
+#define COMPAT_PSR_IT_MASK 0x0600fc00 /* If-Then execution state mask */
+
+/* AArch64 SPSR bits */
+#define PSR_F_BIT 0x00000040
+#define PSR_I_BIT 0x00000080
+#define PSR_A_BIT 0x00000100
+#define PSR_D_BIT 0x00000200
+#define PSR_Q_BIT 0x08000000
+#define PSR_V_BIT 0x10000000
+#define PSR_C_BIT 0x20000000
+#define PSR_Z_BIT 0x40000000
+#define PSR_N_BIT 0x80000000
+
+/*
+ * Groups of PSR bits
+ */
+#define PSR_f 0xff000000 /* Flags */
+#define PSR_s 0x00ff0000 /* Status */
+#define PSR_x 0x0000ff00 /* Extension */
+#define PSR_c 0x000000ff /* Control */
+
+/*
+ * These are 'magic' values for PTRACE_PEEKUSR that return info about where a
+ * process is located in memory.
+ */
+#define PT_TEXT_ADDR 0x10000
+#define PT_DATA_ADDR 0x10004
+#define PT_TEXT_END_ADDR 0x10008
+
+#ifndef __ASSEMBLY__
+
+/*
+ * User structures for general purpose and floating point registers.
+ */
+struct user_pt_regs {
+ __u64 regs[31];
+ __u64 sp;
+ __u64 pc;
+ __u64 pstate;
+};
+
+struct user_fpsimd_state {
+ __uint128_t vregs[32];
+ __u32 fpsr;
+ __u32 fpcr;
+};
+
+#ifdef __KERNEL__
+
+#ifdef CONFIG_AARCH32_EMULATION
+/* sizeof(struct user) for AArch32 */
+#define COMPAT_USER_SZ 296
+/* AArch32 uses x13 as the stack pointer... */
+#define compat_sp regs[13]
+/* ... and x14 as the link register. */
+#define compat_lr regs[14]
+#endif
+
+/*
+ * This struct defines the way the registers are stored on the stack during an
+ * exception. Note that sizeof(struct pt_regs) has to be a multiple of 16 (for
+ * stack alignment). struct user_pt_regs must form a prefix of struct pt_regs.
+ */
+struct pt_regs {
+ union {
+ struct user_pt_regs user_regs;
+ struct {
+ u64 regs[31];
+ u64 sp;
+ u64 pc;
+ u64 pstate;
+ };
+ };
+ u64 orig_x0;
+ u64 syscallno;
+};
+
+#define arch_has_single_step() (1)
+
+#ifdef CONFIG_AARCH32_EMULATION
+#define compat_thumb_mode(regs) \
+ (((regs)->pstate & COMPAT_PSR_T_BIT))
+#else
+#define compat_thumb_mode(regs) (0)
+#endif
+
+#define user_mode(regs) \
+ (((regs)->pstate & PSR_MODE_MASK) == PSR_MODE_EL0t)
+
+#define compat_user_mode(regs) \
+ (((regs)->pstate & (PSR_MODE32_BIT | PSR_MODE_MASK)) == \
+ (PSR_MODE32_BIT | PSR_MODE_EL0t))
+
+#define processor_mode(regs) \
+ ((regs)->pstate & PSR_MODE_MASK)
+
+#define interrupts_enabled(regs) \
+ (!((regs)->pstate & PSR_I_BIT))
+
+#define fast_interrupts_enabled(regs) \
+ (!((regs)->pstate & PSR_F_BIT))
+
+#define user_stack_pointer(regs) \
+ ((regs)->sp)
+
+/*
+ * Are the current registers suitable for user mode? (used to maintain
+ * security in signal handlers)
+ */
+static inline int valid_user_regs(struct user_pt_regs *regs)
+{
+ if (user_mode(regs) && (regs->pstate & PSR_I_BIT) == 0) {
+ regs->pstate &= ~(PSR_F_BIT | PSR_A_BIT);
+
+ /* The T bit is reserved for AArch64 */
+ if (!(regs->pstate & PSR_MODE32_BIT))
+ regs->pstate &= ~COMPAT_PSR_T_BIT;
+
+ return 1;
+ }
+
+ /*
+ * Force PSR to something logical...
+ */
+ regs->pstate &= PSR_f | PSR_s | (PSR_x & ~PSR_A_BIT) | \
+ COMPAT_PSR_T_BIT | PSR_MODE32_BIT;
+
+ if (!(regs->pstate & PSR_MODE32_BIT)) {
+ regs->pstate &= ~COMPAT_PSR_T_BIT;
+ regs->pstate |= PSR_MODE_EL0t;
+ }
+
+ return 0;
+}
+
+#define instruction_pointer(regs) (regs)->pc
+
+#ifdef CONFIG_SMP
+extern unsigned long profile_pc(struct pt_regs *regs);
+#else
+#define profile_pc(regs) instruction_pointer(regs)
+#endif
+
+extern int aarch32_break_trap(struct pt_regs *regs);
+
+#endif /* __KERNEL__ */
+
+#endif /* __ASSEMBLY__ */
+
+#endif
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
new file mode 100644
index 0000000..7318f6d
--- /dev/null
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_STACKTRACE_H
+#define __ASM_STACKTRACE_H
+
+struct stackframe {
+ unsigned long fp;
+ unsigned long sp;
+ unsigned long pc;
+};
+
+extern int unwind_frame(struct stackframe *frame);
+extern void walk_stackframe(struct stackframe *frame,
+ int (*fn)(struct stackframe *, void *), void *data);
+
+#endif /* __ASM_STACKTRACE_H */
diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
new file mode 100644
index 0000000..10ca8ff
--- /dev/null
+++ b/arch/arm64/include/asm/traps.h
@@ -0,0 +1,30 @@
+/*
+ * Based on arch/arm/include/asm/traps.h
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_TRAP_H
+#define __ASM_TRAP_H
+
+static inline int in_exception_text(unsigned long ptr)
+{
+ extern char __exception_text_start[];
+ extern char __exception_text_end[];
+
+ return ptr >= (unsigned long)&__exception_text_start &&
+ ptr < (unsigned long)&__exception_text_end;
+}
+
+#endif
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
new file mode 100644
index 0000000..32b96ab
--- /dev/null
+++ b/arch/arm64/kernel/entry.S
@@ -0,0 +1,695 @@
+/*
+ * Low-level exception handling code
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Authors: Catalin Marinas <catalin.marinas@arm.com>
+ * Will Deacon <will.deacon@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+
+#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
+#include <asm/errno.h>
+#include <asm/thread_info.h>
+#include <asm/unistd.h>
+
+/*
+ * Bad Abort numbers
+ *-----------------
+ */
+#define BAD_SYNC 0
+#define BAD_IRQ 1
+#define BAD_FIQ 2
+#define BAD_ERROR 3
+
+ .macro kernel_entry, el, regsize = 64
+ sub sp, sp, #S_FRAME_SIZE - S_LR // room for LR, SP, SPSR, ELR
+ .if \regsize == 32
+ mov w0, w0 // zero upper 32 bits of x0
+ .endif
+ push x28, x29
+ push x26, x27
+ push x24, x25
+ push x22, x23
+ push x20, x21
+ push x18, x19
+ push x16, x17
+ push x14, x15
+ push x12, x13
+ push x10, x11
+ push x8, x9
+ push x6, x7
+ push x4, x5
+ push x2, x3
+ push x0, x1
+ .if \el == 0
+ mrs x21, sp_el0
+ .else
+ add x21, sp, #S_FRAME_SIZE
+ .endif
+ mrs x22, elr_el1
+ mrs x23, spsr_el1
+ stp lr, x21, [sp, #S_LR]
+ stp x22, x23, [sp, #S_PC]
+
+ /*
+ * Set syscallno to -1 by default (overridden later if real syscall).
+ */
+ .if \el == 0
+ mvn x21, xzr
+ str x21, [sp, #S_SYSCALLNO]
+ .endif
+
+ /*
+ * Registers that may be useful after this macro is invoked:
+ *
+ * x21 - aborted SP
+ * x22 - aborted PC
+ * x23 - aborted PSTATE
+ */
+ .endm
+
+ .macro kernel_exit, el, ret = 0
+ ldp x21, x22, [sp, #S_PC] // load ELR, SPSR
+ .if \el == 0
+ ldr x23, [sp, #S_SP] // load return stack pointer
+ .endif
+ .if \ret
+ ldr x1, [sp, #S_X1] // preserve x0 (syscall return)
+ add sp, sp, S_X2
+ .else
+ pop x0, x1
+ .endif
+ pop x2, x3 // load the rest of the registers
+ pop x4, x5
+ pop x6, x7
+ pop x8, x9
+ msr elr_el1, x21 // set up the return data
+ msr spsr_el1, x22
+ .if \el == 0
+ msr sp_el0, x23
+ .endif
+ pop x10, x11
+ pop x12, x13
+ pop x14, x15
+ pop x16, x17
+ pop x18, x19
+ pop x20, x21
+ pop x22, x23
+ pop x24, x25
+ pop x26, x27
+ pop x28, x29
+ ldr lr, [sp], #S_FRAME_SIZE - S_LR // load LR and restore SP
+ eret // return to kernel
+ .endm
+
+ .macro get_thread_info, rd
+ mov \rd, sp
+ and \rd, \rd, #~((1 << 13) - 1) // top of 8K stack
+ .endm
+
+/*
+ * These are the registers used in the syscall handler, and allow us to
+ * have in theory up to 7 arguments to a function - x0 to x6.
+ *
+ * x7 is reserved for the system call number in 32-bit mode.
+ */
+sc_nr .req x25 // number of system calls
+scno .req x26 // syscall number
+stbl .req x27 // syscall table pointer
+tsk .req x28 // current thread_info
+
+/*
+ * Interrupt handling.
+ */
+ .macro irq_handler
+ ldr x1, handle_arch_irq
+ mov x0, sp
+ blr x1
+ .endm
+
+ .text
+
+/*
+ * Exception vectors.
+ */
+ .macro ventry label
+ .align 7
+ b \label
+ .endm
+
+ .align 11
+ENTRY(vectors)
+ ventry el1_sync_invalid // Synchronous EL1t
+ ventry el1_irq_invalid // IRQ EL1t
+ ventry el1_fiq_invalid // FIQ EL1t
+ ventry el1_error_invalid // Error EL1t
+
+ ventry el1_sync // Synchronous EL1h
+ ventry el1_irq // IRQ EL1h
+ ventry el1_fiq_invalid // FIQ EL1h
+ ventry el1_error_invalid // Error EL1h
+
+ ventry el0_sync // Synchronous 64-bit EL0
+ ventry el0_irq // IRQ 64-bit EL0
+ ventry el0_fiq_invalid // FIQ 64-bit EL0
+ ventry el0_error_invalid // Error 64-bit EL0
+
+#ifdef CONFIG_AARCH32_EMULATION
+ ventry el0_sync_compat // Synchronous 32-bit EL0
+ ventry el0_irq_compat // IRQ 32-bit EL0
+ ventry el0_fiq_invalid_compat // FIQ 32-bit EL0
+ ventry el0_error_invalid_compat // Error 32-bit EL0
+#else
+ ventry el0_sync_invalid // Synchronous 32-bit EL0
+ ventry el0_irq_invalid // IRQ 32-bit EL0
+ ventry el0_fiq_invalid // FIQ 32-bit EL0
+ ventry el0_error_invalid // Error 32-bit EL0
+#endif
+END(vectors)
+
+/*
+ * Invalid mode handlers
+ */
+ .macro inv_entry, el, reason, regsize = 64
+ kernel_entry el, \regsize
+ mov x0, sp
+ mov x1, #\reason
+ mrs x2, esr_el1
+ b bad_mode
+ .endm
+
+el0_sync_invalid:
+ inv_entry 0, BAD_SYNC
+ENDPROC(el0_sync_invalid)
+
+el0_irq_invalid:
+ inv_entry 0, BAD_IRQ
+ENDPROC(el0_irq_invalid)
+
+el0_fiq_invalid:
+ inv_entry 0, BAD_FIQ
+ENDPROC(el0_fiq_invalid)
+
+el0_error_invalid:
+ inv_entry 0, BAD_ERROR
+ENDPROC(el0_error_invalid)
+
+#ifdef CONFIG_AARCH32_EMULATION
+el0_fiq_invalid_compat:
+ inv_entry 0, BAD_FIQ, 32
+ENDPROC(el0_fiq_invalid_compat)
+
+el0_error_invalid_compat:
+ inv_entry 0, BAD_ERROR, 32
+ENDPROC(el0_error_invalid_compat)
+#endif
+
+el1_sync_invalid:
+ inv_entry 1, BAD_SYNC
+ENDPROC(el1_sync_invalid)
+
+el1_irq_invalid:
+ inv_entry 1, BAD_IRQ
+ENDPROC(el1_irq_invalid)
+
+el1_fiq_invalid:
+ inv_entry 1, BAD_FIQ
+ENDPROC(el1_fiq_invalid)
+
+el1_error_invalid:
+ inv_entry 1, BAD_ERROR
+ENDPROC(el1_error_invalid)
+
+/*
+ * EL1 mode handlers.
+ */
+ .align 6
+el1_sync:
+ kernel_entry 1
+ mrs x1, esr_el1 // read the syndrome register
+ lsr x24, x1, #26 // exception class
+ cmp x24, #0x25 // data abort in EL1
+ b.eq el1_da
+ cmp x24, #0x18 // configurable trap
+ b.eq el1_undef
+ cmp x24, #0x26 // stack alignment exception
+ b.eq el1_sp_pc
+ cmp x24, #0x22 // pc alignment exception
+ b.eq el1_sp_pc
+ cmp x24, #0x00 // unknown exception in EL1
+ b.eq el1_undef
+ cmp x24, #0x30 // debug exception in EL1
+ b.ge el1_dbg
+ b el1_inv
+el1_da:
+ /*
+ * Data abort handling
+ */
+ mrs x0, far_el1
+ enable_dbg_if_not_stepping x2
+ // re-enable interrupts if they were enabled in the aborted context
+ tbnz x23, #7, 1f // PSR_I_BIT
+ enable_irq
+1:
+ mov x2, sp // struct pt_regs
+ bl do_mem_abort
+
+ // disable interrupts before pulling preserved data off the stack
+ disable_irq
+ kernel_exit 1
+el1_sp_pc:
+ /*
+ *Stack or PC alignment exception handling
+ */
+ mrs x0, far_el1
+ mov x1, x25
+ mov x2, sp
+ b do_sp_pc_abort
+el1_undef:
+ /*
+ *Undefined instruction
+ */
+ mov x0, sp
+ b do_undefinstr
+el1_dbg:
+ /*
+ * Debug exception handling
+ */
+ tbz x24, #0, el1_inv // EL1 only
+ mrs x0, far_el1
+ mov x2, sp // struct pt_regs
+ bl do_debug_exception
+
+ kernel_exit 1
+el1_inv:
+ // TODO: add support for undefined instructions in kernel mode
+ mov x0, sp
+ mov x1, #BAD_SYNC
+ mrs x2, esr_el1
+ b bad_mode
+ENDPROC(el1_sync)
+
+ .align 6
+el1_irq:
+ kernel_entry 1
+ enable_dbg_if_not_stepping x0
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_off
+#endif
+#ifdef CONFIG_PREEMPT
+ get_thread_info tsk
+ ldr x24, [tsk, #TI_PREEMPT] // get preempt count
+ add x0, x24, #1 // increment it
+ str x0, [tsk, #TI_PREEMPT]
+#endif
+ irq_handler
+#ifdef CONFIG_PREEMPT
+ str x24, [tsk, #TI_PREEMPT] // restore preempt count
+ cbnz x24, 1f // preempt count != 0
+ ldr x0, [tsk, #TI_FLAGS] // get flags
+ tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
+ bl el1_preempt
+1:
+#endif
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_on
+#endif
+ kernel_exit 1
+ENDPROC(el1_irq)
+
+#ifdef CONFIG_PREEMPT
+el1_preempt:
+ mov x24, lr
+1: enable_dbg
+ bl preempt_schedule_irq // irq en/disable is done inside
+ ldr x0, [tsk, #TI_FLAGS] // get new tasks TI_FLAGS
+ tbnz x0, #TIF_NEED_RESCHED, 1b // needs rescheduling?
+ ret x24
+#endif
+
+/*
+ * EL0 mode handlers.
+ */
+ .align 6
+el0_sync:
+ kernel_entry 0
+ mrs x25, esr_el1 // read the syndrome register
+ lsr x24, x25, #26 // exception class
+ cmp x24, #0x15 // SVC in 64-bit state
+ b.eq el0_svc
+ adr lr, ret_from_exception
+ cmp x24, #0x24 // data abort in EL0
+ b.eq el0_da
+ cmp x24, #0x20 // instruction abort in EL0
+ b.eq el0_ia
+ cmp x24, #0x07 // FP/ASIMD access
+ b.eq el0_fpsimd_acc
+ cmp x24, #0x2c // FP/ASIMD exception
+ b.eq el0_fpsimd_exc
+ cmp x24, #0x18 // configurable trap
+ b.eq el0_undef
+ cmp x24, #0x26 // stack alignment exception
+ b.eq el0_sp_pc
+ cmp x24, #0x22 // pc alignment exception
+ b.eq el0_sp_pc
+ cmp x24, #0x00 // unknown exception in EL0
+ b.eq el0_undef
+ cmp x24, #0x30 // debug exception in EL0
+ b.ge el0_dbg
+ b el0_inv
+
+#ifdef CONFIG_AARCH32_EMULATION
+ .align 6
+el0_sync_compat:
+ kernel_entry 0, 32
+ mrs x25, esr_el1 // read the syndrome register
+ lsr x24, x25, #26 // exception class
+ cmp x24, #0x11 // SVC in 32-bit state
+ b.eq el0_svc_compat
+ adr lr, ret_from_exception
+ cmp x24, #0x24 // data abort in EL0
+ b.eq el0_da
+ cmp x24, #0x20 // instruction abort in EL0
+ b.eq el0_ia
+ cmp x24, #0x07 // FP/ASIMD access
+ b.eq el0_fpsimd_acc
+ cmp x24, #0x28 // FP/ASIMD exception
+ b.eq el0_fpsimd_exc
+ cmp x24, #0x00 // unknown exception in EL0
+ b.eq el0_undef
+ cmp x24, #0x30 // debug exception in EL0
+ b.ge el0_dbg
+ b el0_inv
+el0_svc_compat:
+ /*
+ * AArch32 syscall handling
+ */
+ adr stbl, compat_sys_call_table // load compat syscall table pointer
+ uxtw scno, w7 // syscall number in w7 (r7)
+ mov sc_nr, #__NR_compat_syscalls
+ b el0_svc_naked
+
+ .align 6
+el0_irq_compat:
+ kernel_entry 0, 32
+ b el0_irq_naked
+#endif
+
+el0_da:
+ /*
+ * Data abort handling
+ */
+ mrs x0, far_el1
+ disable_step x1
+ isb
+ enable_dbg
+ // enable interrupts before calling the main handler
+ enable_irq
+ mov x1, x25
+ mov x2, sp
+ b do_mem_abort
+el0_ia:
+ /*
+ * Instruction abort handling
+ */
+ mrs x0, far_el1
+ disable_step x1
+ isb
+ enable_dbg
+ // enable interrupts before calling the main handler
+ enable_irq
+ orr x1, x25, #1 << 24 // use reserved ISS bit for instruction aborts
+ mov x2, sp
+ b do_mem_abort
+el0_fpsimd_acc:
+ /*
+ * Floating Point or Advanced SIMD access
+ */
+ mov x0, x25
+ mov x1, sp
+ b do_fpsimd_acc
+el0_fpsimd_exc:
+ /*
+ * Floating Point or Advanced SIMD exception
+ */
+ mov x0, x25
+ mov x1, sp
+ b do_fpsimd_exc
+el0_sp_pc:
+ /*
+ * Stack or PC alignment exception handling
+ */
+ mrs x0, far_el1
+ disable_step x1
+ isb
+ enable_dbg
+ // enable interrupts before calling the main handler
+ enable_irq
+ mov x1, x25
+ mov x2, sp
+ b do_sp_pc_abort
+el0_undef:
+ /*
+ *Undefined instruction
+ */
+ mov x0, sp
+ b do_undefinstr
+el0_dbg:
+ /*
+ * Debug exception handling
+ */
+ tbnz x24, #0, el0_inv // EL0 only
+ mrs x0, far_el1
+ disable_step x1
+ mov x1, x25
+ mov x2, sp
+ b do_debug_exception
+el0_inv:
+ mov x0, sp
+ mov x1, #BAD_SYNC
+ mrs x2, esr_el1
+ b bad_mode
+ENDPROC(el0_sync)
+
+ .align 6
+el0_irq:
+ kernel_entry 0
+el0_irq_naked:
+ disable_step x1
+ isb
+ enable_dbg
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_off
+#endif
+ get_thread_info tsk
+#ifdef CONFIG_PREEMPT
+ ldr x24, [tsk, #TI_PREEMPT] // get preempt count
+ add x23, x24, #1 // increment it
+ str x23, [tsk, #TI_PREEMPT]
+#endif
+ irq_handler
+#ifdef CONFIG_PREEMPT
+ ldr x0, [tsk, #TI_PREEMPT]
+ str x24, [tsk, #TI_PREEMPT]
+ cmp x0, x23
+ b.eq 1f
+ mov x1, #0
+ str x1, [x1] // BUG
+1:
+#endif
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_on
+#endif
+ b ret_to_user
+ENDPROC(el0_irq)
+
+/*
+ * This is the return code to user mode for abort handlers
+ */
+ENTRY(ret_from_exception)
+ get_thread_info tsk
+ b ret_to_user
+ENDPROC(ret_from_exception)
+
+/*
+ * Register switch for AArch64. The callee-saved registers need to be saved
+ * and restored. On entry:
+ * x0 = previous task_struct (must be preserved across the switch)
+ * x1 = next task_struct
+ * Previous and next are guaranteed not to be the same.
+ *
+ */
+ENTRY(cpu_switch_to)
+ add x8, x0, #THREAD_CPU_CONTEXT
+ mov x9, sp
+ stp x19, x20, [x8], #16 // store callee-saved registers
+ stp x21, x22, [x8], #16
+ stp x23, x24, [x8], #16
+ stp x25, x26, [x8], #16
+ stp x27, x28, [x8], #16
+ stp x29, x9, [x8], #16
+ str lr, [x8]
+ add x8, x1, #THREAD_CPU_CONTEXT
+ ldp x19, x20, [x8], #16 // restore callee-saved registers
+ ldp x21, x22, [x8], #16
+ ldp x23, x24, [x8], #16
+ ldp x25, x26, [x8], #16
+ ldp x27, x28, [x8], #16
+ ldp x29, x9, [x8], #16
+ ldr lr, [x8]
+ mov sp, x9
+ ret
+ENDPROC(cpu_switch_to)
+
+/*
+ * This is the fast syscall return path. We do as little as possible here,
+ * and this includes saving x0 back into the kernel stack.
+ */
+ret_fast_syscall:
+ disable_irq // disable interrupts
+ ldr x1, [tsk, #TI_FLAGS]
+ and x2, x1, #_TIF_WORK_MASK
+ cbnz x2, fast_work_pending
+ tbz x1, #TIF_SINGLESTEP, fast_exit
+ disable_dbg
+ enable_step x2
+fast_exit:
+ kernel_exit 0, ret = 1
+
+/*
+ * Ok, we need to do extra processing, enter the slow path.
+ */
+fast_work_pending:
+ str x0, [sp, #S_X0] // returned x0
+work_pending:
+ tbnz x1, #TIF_NEED_RESCHED, work_resched
+ /* TIF_SIGPENDING or TIF_NOTIFY_RESUME case */
+ ldr x2, [sp, #S_PSTATE]
+ mov x0, sp // 'regs'
+ tst x2, #PSR_MODE_MASK // user mode regs?
+ b.ne no_work_pending // returning to kernel
+ bl do_notify_resume
+ b ret_to_user
+work_resched:
+ enable_dbg
+ bl schedule
+
+/*
+ * "slow" syscall return path.
+ */
+ENTRY(ret_to_user)
+ disable_irq // disable interrupts
+ ldr x1, [tsk, #TI_FLAGS]
+ and x2, x1, #_TIF_WORK_MASK
+ cbnz x2, work_pending
+ tbz x1, #TIF_SINGLESTEP, no_work_pending
+ disable_dbg
+ enable_step x2
+no_work_pending:
+ kernel_exit 0, ret = 0
+ENDPROC(ret_to_user)
+
+/*
+ * This is how we return from a fork.
+ */
+ENTRY(ret_from_fork)
+ bl schedule_tail
+ get_thread_info tsk
+ b ret_to_user
+ENDPROC(ret_from_fork)
+
+/*
+ * SVC handler.
+ */
+ .align 6
+ENTRY(el0_svc)
+ adrp stbl, sys_call_table // load syscall table pointer
+ uxtw scno, w8 // syscall number in w8
+ mov sc_nr, #__NR_syscalls
+el0_svc_naked: // compat entry point
+ stp x0, scno, [sp, #S_ORIG_X0] // save the original x0 and syscall number
+ disable_step x16
+ isb
+ enable_dbg
+ enable_irq
+
+ get_thread_info tsk
+ ldr x16, [tsk, #TI_FLAGS] // check for syscall tracing
+ tbnz x16, #TIF_SYSCALL_TRACE, __sys_trace // are we tracing syscalls?
+ adr lr, ret_fast_syscall // return address
+ cmp scno, sc_nr // check upper syscall limit
+ b.hs ni_sys
+ ldr x16, [stbl, scno, lsl #3] // address in the syscall table
+ br x16 // call sys_* routine
+ni_sys:
+ mov x0, sp
+ b do_ni_syscall
+ENDPROC(el0_svc)
+
+ /*
+ * This is the really slow path. We're going to be doing context
+ * switches, and waiting for our parent to respond.
+ */
+__sys_trace:
+ mov x1, sp
+ mov w0, #0 // trace entry
+ bl syscall_trace
+ adr lr, __sys_trace_return // return address
+ uxtw scno, w0 // syscall number (possibly new)
+ mov x1, sp // pointer to regs
+ cmp scno, sc_nr // check upper syscall limit
+ b.hs ni_sys
+ ldp x0, x1, [sp] // restore the syscall args
+ ldp x2, x3, [sp, #S_X2]
+ ldp x4, x5, [sp, #S_X4]
+ ldp x6, x7, [sp, #S_X6]
+ ldr x16, [stbl, scno, lsl #3] // address in the syscall table
+ br x16 // call sys_* routine
+
+__sys_trace_return:
+ str x0, [sp] // save returned x0
+ mov x1, sp
+ mov w0, #1 // trace exit
+ bl syscall_trace
+ b ret_to_user
+
+/*
+ * Special system call wrappers.
+ */
+ENTRY(sys_execve_wrapper)
+ mov x3, sp
+ b sys_execve
+ENDPROC(sys_execve_wrapper)
+
+ENTRY(sys_clone_wrapper)
+ mov x5, sp
+ b sys_clone
+ENDPROC(sys_clone_wrapper)
+
+ENTRY(sys_rt_sigreturn_wrapper)
+ mov x0, sp
+ b sys_rt_sigreturn
+ENDPROC(sys_rt_sigreturn_wrapper)
+
+ENTRY(sys_sigaltstack_wrapper)
+ ldr x2, [sp, #S_SP]
+ b sys_sigaltstack
+ENDPROC(sys_sigaltstack_wrapper)
+
+ENTRY(handle_arch_irq)
+ .quad 0
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
new file mode 100644
index 0000000..d25459f
--- /dev/null
+++ b/arch/arm64/kernel/stacktrace.c
@@ -0,0 +1,127 @@
+/*
+ * Stack tracing support
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+
+#include <asm/stacktrace.h>
+
+/*
+ * AArch64 PCS assigns the frame pointer to x29.
+ *
+ * A simple function prologue looks like this:
+ * sub sp, sp, #0x10
+ * stp x29, x30, [sp]
+ * mov x29, sp
+ *
+ * A simple function epilogue looks like this:
+ * mov sp, x29
+ * ldp x29, x30, [sp]
+ * add sp, sp, #0x10
+ */
+int unwind_frame(struct stackframe *frame)
+{
+ unsigned long high, low;
+ unsigned long fp = frame->fp;
+
+ low = frame->sp;
+ high = ALIGN(low, THREAD_SIZE);
+
+ if (fp < low || fp > high || fp & 0xf)
+ return -EINVAL;
+
+ frame->sp = fp + 0x10;
+ frame->fp = *(unsigned long *)(fp);
+ frame->pc = *(unsigned long *)(fp + 8);
+
+ return 0;
+}
+
+void notrace walk_stackframe(struct stackframe *frame,
+ int (*fn)(struct stackframe *, void *), void *data)
+{
+ while (1) {
+ int ret;
+
+ if (fn(frame, data))
+ break;
+ ret = unwind_frame(frame);
+ if (ret < 0)
+ break;
+ }
+}
+EXPORT_SYMBOL(walk_stackframe);
+
+#ifdef CONFIG_STACKTRACE
+struct stack_trace_data {
+ struct stack_trace *trace;
+ unsigned int no_sched_functions;
+ unsigned int skip;
+};
+
+static int save_trace(struct stackframe *frame, void *d)
+{
+ struct stack_trace_data *data = d;
+ struct stack_trace *trace = data->trace;
+ unsigned long addr = frame->pc;
+
+ if (data->no_sched_functions && in_sched_functions(addr))
+ return 0;
+ if (data->skip) {
+ data->skip--;
+ return 0;
+ }
+
+ trace->entries[trace->nr_entries++] = addr;
+
+ return trace->nr_entries >= trace->max_entries;
+}
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+ struct stack_trace_data data;
+ struct stackframe frame;
+
+ data.trace = trace;
+ data.skip = trace->skip;
+
+ if (tsk != current) {
+ data.no_sched_functions = 1;
+ frame.fp = thread_saved_fp(tsk);
+ frame.sp = thread_saved_sp(tsk);
+ frame.pc = thread_saved_pc(tsk);
+ } else {
+ register unsigned long current_sp asm("sp");
+ data.no_sched_functions = 0;
+ frame.fp = (unsigned long)__builtin_frame_address(0);
+ frame.sp = current_sp;
+ frame.pc = (unsigned long)save_stack_trace_tsk;
+ }
+
+ walk_stackframe(&frame, save_trace, &data);
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ save_stack_trace_tsk(current, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+#endif
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
new file mode 100644
index 0000000..8712a8e
--- /dev/null
+++ b/arch/arm64/kernel/traps.c
@@ -0,0 +1,357 @@
+/*
+ * Based on arch/arm/kernel/traps.c
+ *
+ * Copyright (C) 1995-2009 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/signal.h>
+#include <linux/personality.h>
+#include <linux/kallsyms.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/hardirq.h>
+#include <linux/kdebug.h>
+#include <linux/module.h>
+#include <linux/kexec.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+
+#include <asm/atomic.h>
+#include <asm/traps.h>
+#include <asm/stacktrace.h>
+#include <asm/exception.h>
+#include <asm/system_misc.h>
+
+static const char *handler[]= {
+ "Synchronous Abort",
+ "IRQ",
+ "FIQ",
+ "Error"
+};
+
+int show_unhandled_signals = 1;
+
+/*
+ * Dump out the contents of some memory nicely...
+ */
+static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
+ unsigned long top)
+{
+ unsigned long first;
+ mm_segment_t fs;
+ int i;
+
+ /*
+ * We need to switch to kernel mode so that we can use __get_user
+ * to safely read from kernel space. Note that we now dump the
+ * code first, just in case the backtrace kills us.
+ */
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+
+ printk("%s%s(0x%016lx to 0x%016lx)\n", lvl, str, bottom, top);
+
+ for (first = bottom & ~31; first < top; first += 32) {
+ unsigned long p;
+ char str[sizeof(" 12345678") * 8 + 1];
+
+ memset(str, ' ', sizeof(str));
+ str[sizeof(str) - 1] = '\0';
+
+ for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
+ if (p >= bottom && p < top) {
+ unsigned int val;
+ if (__get_user(val, (unsigned int *)p) == 0)
+ sprintf(str + i * 9, " %08x", val);
+ else
+ sprintf(str + i * 9, " ????????");
+ }
+ }
+ printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
+ }
+
+ set_fs(fs);
+}
+
+static void dump_backtrace_entry(unsigned long where, unsigned long stack)
+{
+ print_ip_sym(where);
+ if (in_exception_text(where))
+ dump_mem("", "Exception stack", stack,
+ stack + sizeof(struct pt_regs));
+}
+
+static void dump_instr(const char *lvl, struct pt_regs *regs)
+{
+ unsigned long addr = instruction_pointer(regs);
+ mm_segment_t fs;
+ char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
+ int i;
+
+ /*
+ * We need to switch to kernel mode so that we can use __get_user
+ * to safely read from kernel space. Note that we now dump the
+ * code first, just in case the backtrace kills us.
+ */
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+
+ for (i = -4; i < 1; i++) {
+ unsigned int val, bad;
+
+ bad = __get_user(val, &((u32 *)addr)[i]);
+
+ if (!bad)
+ p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
+ else {
+ p += sprintf(p, "bad PC value");
+ break;
+ }
+ }
+ printk("%sCode: %s\n", lvl, str);
+
+ set_fs(fs);
+}
+
+static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
+{
+ struct stackframe frame;
+ const register unsigned long current_sp asm ("sp");
+
+ pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
+
+ if (!tsk)
+ tsk = current;
+
+ if (regs) {
+ frame.fp = regs->regs[29];
+ frame.sp = regs->sp;
+ frame.pc = regs->pc;
+ } else if (tsk == current) {
+ frame.fp = (unsigned long)__builtin_frame_address(0);
+ frame.sp = current_sp;
+ frame.pc = (unsigned long)dump_backtrace;
+ } else {
+ /*
+ * task blocked in __switch_to
+ */
+ frame.fp = thread_saved_fp(tsk);
+ frame.sp = thread_saved_sp(tsk);
+ frame.pc = thread_saved_pc(tsk);
+ }
+
+ printk("Call trace:\n");
+ while (1) {
+ unsigned long where = frame.pc;
+ int ret;
+
+ ret = unwind_frame(&frame);
+ if (ret < 0)
+ break;
+ dump_backtrace_entry(where, frame.sp);
+ }
+}
+
+void dump_stack(void)
+{
+ dump_backtrace(NULL, NULL);
+}
+
+EXPORT_SYMBOL(dump_stack);
+
+void show_stack(struct task_struct *tsk, unsigned long *sp)
+{
+ dump_backtrace(NULL, tsk);
+ barrier();
+}
+
+#ifdef CONFIG_PREEMPT
+#define S_PREEMPT " PREEMPT"
+#else
+#define S_PREEMPT ""
+#endif
+#ifdef CONFIG_SMP
+#define S_SMP " SMP"
+#else
+#define S_SMP ""
+#endif
+
+static int __die(const char *str, int err, struct thread_info *thread,
+ struct pt_regs *regs)
+{
+ struct task_struct *tsk = thread->task;
+ static int die_counter;
+ int ret;
+
+ pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
+ str, err, ++die_counter);
+
+ /* trap and error numbers are mostly meaningless on ARM */
+ ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
+ if (ret == NOTIFY_STOP)
+ return ret;
+
+ print_modules();
+ __show_regs(regs);
+ pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
+ TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
+
+ if (!user_mode(regs) || in_interrupt()) {
+ dump_mem(KERN_EMERG, "Stack: ", regs->sp,
+ THREAD_SIZE + (unsigned long)task_stack_page(tsk));
+ dump_backtrace(regs, tsk);
+ dump_instr(KERN_EMERG, regs);
+ }
+
+ return ret;
+}
+
+DEFINE_SPINLOCK(die_lock);
+
+/*
+ * This function is protected against re-entrancy.
+ */
+void die(const char *str, struct pt_regs *regs, int err)
+{
+ struct thread_info *thread = current_thread_info();
+ int ret;
+
+ oops_enter();
+
+ spin_lock_irq(&die_lock);
+ console_verbose();
+ bust_spinlocks(1);
+ ret = __die(str, err, thread, regs);
+
+ if (regs && kexec_should_crash(thread->task))
+ crash_kexec(regs);
+
+ bust_spinlocks(0);
+ add_taint(TAINT_DIE);
+ spin_unlock_irq(&die_lock);
+ oops_exit();
+
+ if (in_interrupt())
+ panic("Fatal exception in interrupt");
+ if (panic_on_oops)
+ panic("Fatal exception");
+ if (ret != NOTIFY_STOP)
+ do_exit(SIGSEGV);
+}
+
+void arm64_notify_die(const char *str, struct pt_regs *regs,
+ struct siginfo *info, int err)
+{
+ if (user_mode(regs))
+ force_sig_info(info->si_signo, info, current);
+ else
+ die(str, regs, err);
+}
+
+asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
+{
+ siginfo_t info;
+ void __user *pc = (void __user *)instruction_pointer(regs);
+
+#ifdef CONFIG_AARCH32_EMULATION
+ /* check for AArch32 breakpoint instructions */
+ if (compat_user_mode(regs) && aarch32_break_trap(regs) == 0)
+ return;
+#endif
+
+ if (show_unhandled_signals) {
+ pr_info("%s[%d]: undefined instruction: pc=%p\n",
+ current->comm, task_pid_nr(current), pc);
+ dump_instr(KERN_INFO, regs);
+ }
+
+ info.si_signo = SIGILL;
+ info.si_errno = 0;
+ info.si_code = ILL_ILLOPC;
+ info.si_addr = pc;
+
+ arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
+}
+
+long compat_arm_syscall(struct pt_regs *regs);
+
+asmlinkage long do_ni_syscall(struct pt_regs *regs)
+{
+#ifdef CONFIG_AARCH32_EMULATION
+ long ret;
+ if (is_compat_task()) {
+ ret = compat_arm_syscall(regs);
+ if (ret != -ENOSYS)
+ return ret;
+ }
+#endif
+
+ if (show_unhandled_signals) {
+ pr_info("%s[%d]: syscall %d\n", current->comm,
+ task_pid_nr(current), (int)regs->syscallno);
+ dump_instr("", regs);
+ if (user_mode(regs))
+ __show_regs(regs);
+ }
+
+ return sys_ni_syscall();
+}
+
+/*
+ * bad_mode handles the impossible case in the exception vector.
+ */
+asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
+{
+ console_verbose();
+
+ pr_crit("Bad mode in %s handler detected, code 0x%08x\n",
+ handler[reason], esr);
+
+ die("Oops - bad mode", regs, 0);
+ local_irq_disable();
+ panic("bad mode");
+}
+
+
+void __bad_xchg(volatile void *ptr, int size)
+{
+ printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
+ __builtin_return_address(0), ptr, size);
+ BUG();
+}
+EXPORT_SYMBOL(__bad_xchg);
+
+void __pte_error(const char *file, int line, unsigned long val)
+{
+ printk("%s:%d: bad pte %016lx.\n", file, line, val);
+}
+
+void __pmd_error(const char *file, int line, unsigned long val)
+{
+ printk("%s:%d: bad pmd %016lx.\n", file, line, val);
+}
+
+void __pgd_error(const char *file, int line, unsigned long val)
+{
+ printk("%s:%d: bad pgd %016lx.\n", file, line, val);
+}
+
+void __init trap_init(void)
+{
+ return;
+}


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