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d8a7386897
While looking at an objtool UACCESS warning, it suddenly occurred to me
that it is entirely possible to have an OPTPROBE right in the middle of
an UACCESS region.
In this case we must of course clear FLAGS.AC while running the KPROBE.
Luckily the trampoline already saves/restores [ER]FLAGS, so all we need
to do is inject a CLAC. Unfortunately we cannot use ALTERNATIVE() in the
trampoline text, so we have to frob that manually.
Fixes: ca0bbc70f147 ("sched/x86_64: Don't save flags on context switch")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20200305092130.GU2596@hirez.programming.kicks-ass.net
109 lines
3.0 KiB
C
109 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _ASM_X86_KPROBES_H
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#define _ASM_X86_KPROBES_H
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/*
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* Kernel Probes (KProbes)
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*
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* Copyright (C) IBM Corporation, 2002, 2004
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*
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* See arch/x86/kernel/kprobes.c for x86 kprobes history.
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*/
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#include <asm-generic/kprobes.h>
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#ifdef CONFIG_KPROBES
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/percpu.h>
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#include <asm/text-patching.h>
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#include <asm/insn.h>
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#define __ARCH_WANT_KPROBES_INSN_SLOT
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struct pt_regs;
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struct kprobe;
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typedef u8 kprobe_opcode_t;
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#define MAX_STACK_SIZE 64
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#define CUR_STACK_SIZE(ADDR) \
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(current_top_of_stack() - (unsigned long)(ADDR))
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#define MIN_STACK_SIZE(ADDR) \
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(MAX_STACK_SIZE < CUR_STACK_SIZE(ADDR) ? \
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MAX_STACK_SIZE : CUR_STACK_SIZE(ADDR))
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#define flush_insn_slot(p) do { } while (0)
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/* optinsn template addresses */
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extern __visible kprobe_opcode_t optprobe_template_entry[];
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extern __visible kprobe_opcode_t optprobe_template_clac[];
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extern __visible kprobe_opcode_t optprobe_template_val[];
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extern __visible kprobe_opcode_t optprobe_template_call[];
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extern __visible kprobe_opcode_t optprobe_template_end[];
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#define MAX_OPTIMIZED_LENGTH (MAX_INSN_SIZE + DISP32_SIZE)
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#define MAX_OPTINSN_SIZE \
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(((unsigned long)optprobe_template_end - \
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(unsigned long)optprobe_template_entry) + \
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MAX_OPTIMIZED_LENGTH + JMP32_INSN_SIZE)
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extern const int kretprobe_blacklist_size;
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void arch_remove_kprobe(struct kprobe *p);
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asmlinkage void kretprobe_trampoline(void);
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extern void arch_kprobe_override_function(struct pt_regs *regs);
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/* Architecture specific copy of original instruction*/
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struct arch_specific_insn {
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/* copy of the original instruction */
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kprobe_opcode_t *insn;
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/*
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* boostable = false: This instruction type is not boostable.
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* boostable = true: This instruction has been boosted: we have
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* added a relative jump after the instruction copy in insn,
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* so no single-step and fixup are needed (unless there's
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* a post_handler).
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*/
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bool boostable;
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bool if_modifier;
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};
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struct arch_optimized_insn {
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/* copy of the original instructions */
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kprobe_opcode_t copied_insn[DISP32_SIZE];
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/* detour code buffer */
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kprobe_opcode_t *insn;
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/* the size of instructions copied to detour code buffer */
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size_t size;
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};
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/* Return true (!0) if optinsn is prepared for optimization. */
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static inline int arch_prepared_optinsn(struct arch_optimized_insn *optinsn)
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{
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return optinsn->size;
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}
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struct prev_kprobe {
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struct kprobe *kp;
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unsigned long status;
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unsigned long old_flags;
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unsigned long saved_flags;
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};
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/* per-cpu kprobe control block */
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struct kprobe_ctlblk {
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unsigned long kprobe_status;
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unsigned long kprobe_old_flags;
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unsigned long kprobe_saved_flags;
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struct prev_kprobe prev_kprobe;
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};
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extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
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extern int kprobe_exceptions_notify(struct notifier_block *self,
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unsigned long val, void *data);
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extern int kprobe_int3_handler(struct pt_regs *regs);
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extern int kprobe_debug_handler(struct pt_regs *regs);
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#endif /* CONFIG_KPROBES */
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#endif /* _ASM_X86_KPROBES_H */
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