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arm64: entry: Move ct_user_exit before any other exception
When taking an SError or Debug exception from EL0, we run the C
handler for these exceptions before updating the context tracking
code and unmasking lower priority interrupts.
When booting with nohz_full lockdep tells us we got this wrong:
| =============================
| WARNING: suspicious RCU usage
| 5.3.0-rc2-00010-gb4b5e9dcb11b-dirty #11271 Not tainted
| -----------------------------
| include/linux/rcupdate.h:643 rcu_read_unlock() used illegally wh!
|
| other info that might help us debug this:
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|
| RCU used illegally from idle CPU!
| rcu_scheduler_active = 2, debug_locks = 1
| RCU used illegally from extended quiescent state!
| 1 lock held by a.out/432:
| #0: 00000000c7a79515 (rcu_read_lock){....}, at: brk_handler+0x00
|
| stack backtrace:
| CPU: 1 PID: 432 Comm: a.out Not tainted 5.3.0-rc2-00010-gb4b5e9d1
| Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno De8
| Call trace:
| dump_backtrace+0x0/0x140
| show_stack+0x14/0x20
| dump_stack+0xbc/0x104
| lockdep_rcu_suspicious+0xf8/0x108
| brk_handler+0x164/0x1b0
| do_debug_exception+0x11c/0x278
| el0_dbg+0x14/0x20
Moving the ct_user_exit calls to be before do_debug_exception() means
they are also before trace_hardirqs_off() has been updated. Add a new
ct_user_exit_irqoff macro to avoid the context-tracking code using
irqsave/restore before we've updated trace_hardirqs_off(). To be
consistent, do this everywhere.
The C helper is called enter_from_user_mode() to match x86 in the hope
we can merge them into kernel/context_tracking.c later.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 6c81fe7925 ("arm64: enable context tracking")
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
James Morse
Will Deacon
parent
2d12294248
commit
2671828c3f
@ -30,4 +30,6 @@ static inline u32 disr_to_esr(u64 disr)
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return esr;
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}
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asmlinkage void enter_from_user_mode(void);
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#endif /* __ASM_EXCEPTION_H */
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@ -30,9 +30,9 @@
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* Context tracking subsystem. Used to instrument transitions
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* between user and kernel mode.
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*/
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.macro ct_user_exit
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.macro ct_user_exit_irqoff
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#ifdef CONFIG_CONTEXT_TRACKING
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bl context_tracking_user_exit
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bl enter_from_user_mode
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#endif
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.endm
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@ -792,8 +792,8 @@ el0_cp15:
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/*
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* Trapped CP15 (MRC, MCR, MRRC, MCRR) instructions
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*/
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ct_user_exit_irqoff
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enable_daif
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ct_user_exit
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mov x0, x25
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mov x1, sp
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bl do_cp15instr
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@ -805,8 +805,8 @@ el0_da:
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* Data abort handling
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*/
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mrs x26, far_el1
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ct_user_exit_irqoff
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enable_daif
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ct_user_exit
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clear_address_tag x0, x26
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mov x1, x25
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mov x2, sp
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@ -818,11 +818,11 @@ el0_ia:
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*/
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mrs x26, far_el1
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gic_prio_kentry_setup tmp=x0
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ct_user_exit_irqoff
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enable_da_f
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#ifdef CONFIG_TRACE_IRQFLAGS
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bl trace_hardirqs_off
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#endif
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ct_user_exit
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mov x0, x26
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mov x1, x25
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mov x2, sp
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@ -832,8 +832,8 @@ el0_fpsimd_acc:
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/*
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* Floating Point or Advanced SIMD access
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*/
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ct_user_exit_irqoff
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enable_daif
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ct_user_exit
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mov x0, x25
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mov x1, sp
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bl do_fpsimd_acc
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@ -842,8 +842,8 @@ el0_sve_acc:
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/*
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* Scalable Vector Extension access
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*/
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ct_user_exit_irqoff
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enable_daif
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ct_user_exit
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mov x0, x25
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mov x1, sp
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bl do_sve_acc
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@ -852,8 +852,8 @@ el0_fpsimd_exc:
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/*
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* Floating Point, Advanced SIMD or SVE exception
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*/
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ct_user_exit_irqoff
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enable_daif
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ct_user_exit
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mov x0, x25
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mov x1, sp
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bl do_fpsimd_exc
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@ -868,11 +868,11 @@ el0_sp_pc:
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* Stack or PC alignment exception handling
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*/
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gic_prio_kentry_setup tmp=x0
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ct_user_exit_irqoff
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enable_da_f
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#ifdef CONFIG_TRACE_IRQFLAGS
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bl trace_hardirqs_off
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#endif
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ct_user_exit
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mov x0, x26
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mov x1, x25
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mov x2, sp
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@ -882,8 +882,8 @@ el0_undef:
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/*
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* Undefined instruction
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*/
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ct_user_exit_irqoff
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enable_daif
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ct_user_exit
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mov x0, sp
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bl do_undefinstr
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b ret_to_user
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@ -891,8 +891,8 @@ el0_sys:
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/*
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* System instructions, for trapped cache maintenance instructions
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*/
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ct_user_exit_irqoff
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enable_daif
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ct_user_exit
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mov x0, x25
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mov x1, sp
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bl do_sysinstr
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@ -902,17 +902,18 @@ el0_dbg:
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* Debug exception handling
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*/
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tbnz x24, #0, el0_inv // EL0 only
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mrs x24, far_el1
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gic_prio_kentry_setup tmp=x3
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mrs x0, far_el1
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ct_user_exit_irqoff
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mov x0, x24
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mov x1, x25
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mov x2, sp
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bl do_debug_exception
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enable_da_f
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ct_user_exit
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b ret_to_user
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el0_inv:
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ct_user_exit_irqoff
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enable_daif
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ct_user_exit
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mov x0, sp
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mov x1, #BAD_SYNC
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mov x2, x25
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@ -925,13 +926,13 @@ el0_irq:
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kernel_entry 0
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el0_irq_naked:
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gic_prio_irq_setup pmr=x20, tmp=x0
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ct_user_exit_irqoff
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enable_da_f
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#ifdef CONFIG_TRACE_IRQFLAGS
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bl trace_hardirqs_off
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#endif
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ct_user_exit
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#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
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tbz x22, #55, 1f
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bl do_el0_irq_bp_hardening
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@ -958,13 +959,14 @@ ENDPROC(el1_error)
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el0_error:
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kernel_entry 0
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el0_error_naked:
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mrs x1, esr_el1
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mrs x25, esr_el1
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gic_prio_kentry_setup tmp=x2
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ct_user_exit_irqoff
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enable_dbg
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mov x0, sp
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mov x1, x25
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bl do_serror
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enable_da_f
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ct_user_exit
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b ret_to_user
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ENDPROC(el0_error)
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@ -7,9 +7,11 @@
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*/
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#include <linux/bug.h>
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#include <linux/context_tracking.h>
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#include <linux/signal.h>
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#include <linux/personality.h>
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#include <linux/kallsyms.h>
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#include <linux/kprobes.h>
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#include <linux/spinlock.h>
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#include <linux/uaccess.h>
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#include <linux/hardirq.h>
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@ -900,6 +902,13 @@ asmlinkage void do_serror(struct pt_regs *regs, unsigned int esr)
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nmi_exit();
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}
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asmlinkage void enter_from_user_mode(void)
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{
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CT_WARN_ON(ct_state() != CONTEXT_USER);
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user_exit_irqoff();
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}
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NOKPROBE_SYMBOL(enter_from_user_mode);
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void __pte_error(const char *file, int line, unsigned long val)
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{
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pr_err("%s:%d: bad pte %016lx.\n", file, line, val);
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