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94b07c1f8c
Stateful CPU architecture extensions may require the signal frame to grow to a size that exceeds the arch's MINSIGSTKSZ #define. However, changing this #define is an ABI break. To allow userspace the option of determining the signal frame size in a more forwards-compatible way, this patch adds a new auxv entry tagged with AT_MINSIGSTKSZ, which provides the maximum signal frame size that the process can observe during its lifetime. If AT_MINSIGSTKSZ is absent from the aux vector, the caller can assume that the MINSIGSTKSZ #define is sufficient. This allows for a consistent interface with older kernels that do not provide AT_MINSIGSTKSZ. The idea is that libc could expose this via sysconf() or some similar mechanism. There is deliberately no AT_SIGSTKSZ. The kernel knows nothing about userspace's own stack overheads and should not pretend to know. For arm64: The primary motivation for this interface is the Scalable Vector Extension, which can require at least 4KB or so of extra space in the signal frame for the largest hardware implementations. To determine the correct value, a "Christmas tree" mode (via the add_all argument) is added to setup_sigframe_layout(), to simulate addition of all possible records to the signal frame at maximum possible size. If this procedure goes wrong somehow, resulting in a stupidly large frame layout and hence failure of sigframe_alloc() to allocate a record to the frame, then this is indicative of a kernel bug. In this case, we WARN() and no attempt is made to populate AT_MINSIGSTKSZ for userspace. For arm64 SVE: The SVE context block in the signal frame needs to be considered too when computing the maximum possible signal frame size. Because the size of this block depends on the vector length, this patch computes the size based not on the thread's current vector length but instead on the maximum possible vector length: this determines the maximum size of SVE context block that can be observed in any signal frame for the lifetime of the process. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
258 lines
6.7 KiB
C
258 lines
6.7 KiB
C
/*
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* Based on arch/arm/include/asm/processor.h
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*
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* Copyright (C) 1995-1999 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_PROCESSOR_H
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#define __ASM_PROCESSOR_H
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#define TASK_SIZE_64 (UL(1) << VA_BITS)
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#define KERNEL_DS UL(-1)
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#define USER_DS (TASK_SIZE_64 - 1)
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#ifndef __ASSEMBLY__
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/*
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* Default implementation of macro that returns current
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* instruction pointer ("program counter").
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*/
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#define current_text_addr() ({ __label__ _l; _l: &&_l;})
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#ifdef __KERNEL__
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#include <linux/build_bug.h>
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#include <linux/cache.h>
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#include <linux/init.h>
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#include <linux/stddef.h>
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#include <linux/string.h>
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#include <asm/alternative.h>
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#include <asm/cpufeature.h>
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#include <asm/hw_breakpoint.h>
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#include <asm/lse.h>
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#include <asm/pgtable-hwdef.h>
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#include <asm/ptrace.h>
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#include <asm/types.h>
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/*
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* TASK_SIZE - the maximum size of a user space task.
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* TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.
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*/
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#ifdef CONFIG_COMPAT
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#define TASK_SIZE_32 UL(0x100000000)
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#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
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TASK_SIZE_32 : TASK_SIZE_64)
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#define TASK_SIZE_OF(tsk) (test_tsk_thread_flag(tsk, TIF_32BIT) ? \
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TASK_SIZE_32 : TASK_SIZE_64)
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#else
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#define TASK_SIZE TASK_SIZE_64
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#endif /* CONFIG_COMPAT */
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#define TASK_UNMAPPED_BASE (PAGE_ALIGN(TASK_SIZE / 4))
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#define STACK_TOP_MAX TASK_SIZE_64
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#ifdef CONFIG_COMPAT
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#define AARCH32_VECTORS_BASE 0xffff0000
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#define STACK_TOP (test_thread_flag(TIF_32BIT) ? \
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AARCH32_VECTORS_BASE : STACK_TOP_MAX)
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#else
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#define STACK_TOP STACK_TOP_MAX
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#endif /* CONFIG_COMPAT */
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extern phys_addr_t arm64_dma_phys_limit;
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#define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit - 1)
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struct debug_info {
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#ifdef CONFIG_HAVE_HW_BREAKPOINT
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/* Have we suspended stepping by a debugger? */
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int suspended_step;
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/* Allow breakpoints and watchpoints to be disabled for this thread. */
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int bps_disabled;
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int wps_disabled;
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/* Hardware breakpoints pinned to this task. */
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struct perf_event *hbp_break[ARM_MAX_BRP];
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struct perf_event *hbp_watch[ARM_MAX_WRP];
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#endif
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};
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struct cpu_context {
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unsigned long x19;
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unsigned long x20;
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unsigned long x21;
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unsigned long x22;
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unsigned long x23;
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unsigned long x24;
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unsigned long x25;
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unsigned long x26;
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unsigned long x27;
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unsigned long x28;
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unsigned long fp;
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unsigned long sp;
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unsigned long pc;
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};
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struct thread_struct {
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struct cpu_context cpu_context; /* cpu context */
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/*
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* Whitelisted fields for hardened usercopy:
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* Maintainers must ensure manually that this contains no
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* implicit padding.
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*/
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struct {
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unsigned long tp_value; /* TLS register */
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unsigned long tp2_value;
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struct user_fpsimd_state fpsimd_state;
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} uw;
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unsigned int fpsimd_cpu;
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void *sve_state; /* SVE registers, if any */
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unsigned int sve_vl; /* SVE vector length */
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unsigned int sve_vl_onexec; /* SVE vl after next exec */
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unsigned long fault_address; /* fault info */
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unsigned long fault_code; /* ESR_EL1 value */
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struct debug_info debug; /* debugging */
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};
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static inline void arch_thread_struct_whitelist(unsigned long *offset,
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unsigned long *size)
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{
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/* Verify that there is no padding among the whitelisted fields: */
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BUILD_BUG_ON(sizeof_field(struct thread_struct, uw) !=
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sizeof_field(struct thread_struct, uw.tp_value) +
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sizeof_field(struct thread_struct, uw.tp2_value) +
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sizeof_field(struct thread_struct, uw.fpsimd_state));
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*offset = offsetof(struct thread_struct, uw);
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*size = sizeof_field(struct thread_struct, uw);
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}
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#ifdef CONFIG_COMPAT
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#define task_user_tls(t) \
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({ \
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unsigned long *__tls; \
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if (is_compat_thread(task_thread_info(t))) \
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__tls = &(t)->thread.uw.tp2_value; \
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else \
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__tls = &(t)->thread.uw.tp_value; \
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__tls; \
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})
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#else
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#define task_user_tls(t) (&(t)->thread.uw.tp_value)
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#endif
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/* Sync TPIDR_EL0 back to thread_struct for current */
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void tls_preserve_current_state(void);
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#define INIT_THREAD { }
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static inline void start_thread_common(struct pt_regs *regs, unsigned long pc)
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{
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memset(regs, 0, sizeof(*regs));
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forget_syscall(regs);
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regs->pc = pc;
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}
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static inline void start_thread(struct pt_regs *regs, unsigned long pc,
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unsigned long sp)
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{
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start_thread_common(regs, pc);
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regs->pstate = PSR_MODE_EL0t;
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regs->sp = sp;
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}
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#ifdef CONFIG_COMPAT
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static inline void compat_start_thread(struct pt_regs *regs, unsigned long pc,
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unsigned long sp)
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{
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start_thread_common(regs, pc);
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regs->pstate = COMPAT_PSR_MODE_USR;
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if (pc & 1)
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regs->pstate |= COMPAT_PSR_T_BIT;
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#ifdef __AARCH64EB__
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regs->pstate |= COMPAT_PSR_E_BIT;
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#endif
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regs->compat_sp = sp;
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}
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#endif
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/* Forward declaration, a strange C thing */
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struct task_struct;
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/* Free all resources held by a thread. */
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extern void release_thread(struct task_struct *);
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unsigned long get_wchan(struct task_struct *p);
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static inline void cpu_relax(void)
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{
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asm volatile("yield" ::: "memory");
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}
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/* Thread switching */
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extern struct task_struct *cpu_switch_to(struct task_struct *prev,
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struct task_struct *next);
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#define task_pt_regs(p) \
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((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1)
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#define KSTK_EIP(tsk) ((unsigned long)task_pt_regs(tsk)->pc)
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#define KSTK_ESP(tsk) user_stack_pointer(task_pt_regs(tsk))
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/*
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* Prefetching support
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*/
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#define ARCH_HAS_PREFETCH
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static inline void prefetch(const void *ptr)
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{
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asm volatile("prfm pldl1keep, %a0\n" : : "p" (ptr));
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}
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#define ARCH_HAS_PREFETCHW
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static inline void prefetchw(const void *ptr)
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{
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asm volatile("prfm pstl1keep, %a0\n" : : "p" (ptr));
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}
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#define ARCH_HAS_SPINLOCK_PREFETCH
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static inline void spin_lock_prefetch(const void *ptr)
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{
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asm volatile(ARM64_LSE_ATOMIC_INSN(
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"prfm pstl1strm, %a0",
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"nop") : : "p" (ptr));
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}
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#define HAVE_ARCH_PICK_MMAP_LAYOUT
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#endif
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void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused);
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void cpu_enable_cache_maint_trap(const struct arm64_cpu_capabilities *__unused);
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void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused);
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extern unsigned long __ro_after_init signal_minsigstksz; /* sigframe size */
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extern void __init minsigstksz_setup(void);
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/* Userspace interface for PR_SVE_{SET,GET}_VL prctl()s: */
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#define SVE_SET_VL(arg) sve_set_current_vl(arg)
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#define SVE_GET_VL() sve_get_current_vl()
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_PROCESSOR_H */
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