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50596b7559
Now that the user space TLS register is assigned on every return to user
space, we can use it to keep the 'current' pointer while running in the
kernel. This removes the need to access it via thread_info, which is
located at the base of the stack, but will be moved out of there in a
subsequent patch.
Use the __builtin_thread_pointer() helper when available - this will
help GCC understand that reloading the value within the same function is
not necessary, even when using the per-task stack protector (which also
generates accesses via the TLS register). For example, the generated
code below loads TPIDRURO only once, and uses it to access both the
stack canary and the preempt_count fields.
<do_one_initcall>:
e92d 41f0 stmdb sp!, {r4, r5, r6, r7, r8, lr}
ee1d 4f70 mrc 15, 0, r4, cr13, cr0, {3}
4606 mov r6, r0
b094 sub sp, #80 ; 0x50
f8d4 34e8 ldr.w r3, [r4, #1256] ; 0x4e8 <- stack canary
9313 str r3, [sp, #76] ; 0x4c
f8d4 8004 ldr.w r8, [r4, #4] <- preempt count
Co-developed-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
164 lines
4.8 KiB
C
164 lines
4.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* arch/arm/include/asm/thread_info.h
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*
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* Copyright (C) 2002 Russell King.
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*/
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#ifndef __ASM_ARM_THREAD_INFO_H
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#define __ASM_ARM_THREAD_INFO_H
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#ifdef __KERNEL__
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#include <linux/compiler.h>
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#include <asm/fpstate.h>
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#include <asm/page.h>
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#ifdef CONFIG_KASAN
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/*
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* KASan uses a lot of extra stack space so the thread size order needs to
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* be increased.
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*/
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#define THREAD_SIZE_ORDER 2
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#else
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#define THREAD_SIZE_ORDER 1
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#endif
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#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
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#define THREAD_START_SP (THREAD_SIZE - 8)
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#ifndef __ASSEMBLY__
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struct task_struct;
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DECLARE_PER_CPU(struct task_struct *, __entry_task);
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#include <asm/types.h>
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struct cpu_context_save {
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__u32 r4;
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__u32 r5;
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__u32 r6;
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__u32 r7;
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__u32 r8;
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__u32 r9;
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__u32 sl;
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__u32 fp;
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__u32 sp;
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__u32 pc;
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__u32 extra[2]; /* Xscale 'acc' register, etc */
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};
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/*
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* low level task data that entry.S needs immediate access to.
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* __switch_to() assumes cpu_context follows immediately after cpu_domain.
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*/
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struct thread_info {
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unsigned long flags; /* low level flags */
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int preempt_count; /* 0 => preemptable, <0 => bug */
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struct task_struct *task; /* main task structure */
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__u32 cpu; /* cpu */
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__u32 cpu_domain; /* cpu domain */
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struct cpu_context_save cpu_context; /* cpu context */
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__u32 abi_syscall; /* ABI type and syscall nr */
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__u8 used_cp[16]; /* thread used copro */
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unsigned long tp_value[2]; /* TLS registers */
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union fp_state fpstate __attribute__((aligned(8)));
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union vfp_state vfpstate;
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#ifdef CONFIG_ARM_THUMBEE
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unsigned long thumbee_state; /* ThumbEE Handler Base register */
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#endif
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};
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#define INIT_THREAD_INFO(tsk) \
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{ \
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.task = &tsk, \
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.flags = 0, \
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.preempt_count = INIT_PREEMPT_COUNT, \
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}
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/*
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* how to get the thread information struct from C
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*/
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static inline struct thread_info *current_thread_info(void) __attribute_const__;
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static inline struct thread_info *current_thread_info(void)
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{
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return (struct thread_info *)
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(current_stack_pointer & ~(THREAD_SIZE - 1));
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}
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#define thread_saved_pc(tsk) \
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((unsigned long)(task_thread_info(tsk)->cpu_context.pc))
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#define thread_saved_sp(tsk) \
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((unsigned long)(task_thread_info(tsk)->cpu_context.sp))
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#ifndef CONFIG_THUMB2_KERNEL
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#define thread_saved_fp(tsk) \
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((unsigned long)(task_thread_info(tsk)->cpu_context.fp))
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#else
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#define thread_saved_fp(tsk) \
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((unsigned long)(task_thread_info(tsk)->cpu_context.r7))
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#endif
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extern void iwmmxt_task_disable(struct thread_info *);
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extern void iwmmxt_task_copy(struct thread_info *, void *);
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extern void iwmmxt_task_restore(struct thread_info *, void *);
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extern void iwmmxt_task_release(struct thread_info *);
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extern void iwmmxt_task_switch(struct thread_info *);
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extern void vfp_sync_hwstate(struct thread_info *);
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extern void vfp_flush_hwstate(struct thread_info *);
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struct user_vfp;
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struct user_vfp_exc;
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extern int vfp_preserve_user_clear_hwstate(struct user_vfp *,
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struct user_vfp_exc *);
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extern int vfp_restore_user_hwstate(struct user_vfp *,
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struct user_vfp_exc *);
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#endif
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/*
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* thread information flags:
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* TIF_USEDFPU - FPU was used by this task this quantum (SMP)
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* TIF_POLLING_NRFLAG - true if poll_idle() is polling TIF_NEED_RESCHED
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*
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* Any bit in the range of 0..15 will cause do_work_pending() to be invoked.
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*/
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#define TIF_SIGPENDING 0 /* signal pending */
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#define TIF_NEED_RESCHED 1 /* rescheduling necessary */
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#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
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#define TIF_UPROBE 3 /* breakpointed or singlestepping */
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#define TIF_SYSCALL_TRACE 4 /* syscall trace active */
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#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
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#define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
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#define TIF_SECCOMP 7 /* seccomp syscall filtering active */
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#define TIF_NOTIFY_SIGNAL 8 /* signal notifications exist */
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#define TIF_USING_IWMMXT 17
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#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
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#define TIF_RESTORE_SIGMASK 20
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#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
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#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
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#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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#define _TIF_UPROBE (1 << TIF_UPROBE)
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#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
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#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
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#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
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#define _TIF_SECCOMP (1 << TIF_SECCOMP)
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#define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL)
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#define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT)
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/* Checks for any syscall work in entry-common.S */
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#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
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_TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP)
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/*
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* Change these and you break ASM code in entry-common.S
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*/
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#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
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_TIF_NOTIFY_RESUME | _TIF_UPROBE | \
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_TIF_NOTIFY_SIGNAL)
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#endif /* __KERNEL__ */
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#endif /* __ASM_ARM_THREAD_INFO_H */
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