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c8b06e3fdd
Since its introduction, the UAO enable call was broken, and useless.
commit 2a6dcb2b5f ("arm64: cpufeature: Schedule enable() calls instead
of calling them via IPI"), fixed the framework so that these calls
are scheduled, so that they can modify PSTATE.
Now it is just useless. Remove it. UAO is enabled by the code patching
which causes get_user() and friends to use the 'ldtr' family of
instructions. This relies on the PSTATE.UAO bit being set to match
addr_limit, which we do in uao_thread_switch() called via __switch_to().
All that is needed to enable UAO is patch the code, and call schedule().
__apply_alternatives_multi_stop() calls stop_machine() when it modifies
the kernel text to enable the alternatives, (including the UAO code in
uao_thread_switch()). Once stop_machine() has finished __switch_to() is
called to reschedule the original task, this causes PSTATE.UAO to be set
appropriately. An explicit enable() call is not needed.
Reported-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
193 lines
4.7 KiB
C
193 lines
4.7 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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/*
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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/string.h>
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#include <asm/alternative.h>
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#include <asm/fpsimd.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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#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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/* 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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};
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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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unsigned long tp_value; /* TLS register */
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#ifdef CONFIG_COMPAT
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unsigned long tp2_value;
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#endif
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struct fpsimd_state fpsimd_state;
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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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#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.tp2_value; \
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else \
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__tls = &(t)->thread.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.tp_value)
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#endif
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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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regs->syscallno = ~0UL;
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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_START_SP + 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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int cpu_enable_pan(void *__unused);
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int cpu_enable_cache_maint_trap(void *__unused);
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#endif /* __ASM_PROCESSOR_H */
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