mirror of https://gitee.com/openkylin/linux.git
arm64: prep stack walkers for THREAD_INFO_IN_TASK
When CONFIG_THREAD_INFO_IN_TASK is selected, task stacks may be freed before a task is destroyed. To account for this, the stacks are refcounted, and when manipulating the stack of another task, it is necessary to get/put the stack to ensure it isn't freed and/or re-used while we do so. This patch reworks the arm64 stack walking code to account for this. When CONFIG_THREAD_INFO_IN_TASK is not selected these perform no refcounting, and this should only be a structural change that does not affect behaviour. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: AKASHI Takahiro <takahiro.akashi@linaro.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: James Morse <james.morse@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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parent
2020a5ae7c
commit
9bbd4c56b0
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@ -350,27 +350,35 @@ struct task_struct *__switch_to(struct task_struct *prev,
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unsigned long get_wchan(struct task_struct *p)
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{
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struct stackframe frame;
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unsigned long stack_page;
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unsigned long stack_page, ret = 0;
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int count = 0;
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if (!p || p == current || p->state == TASK_RUNNING)
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return 0;
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stack_page = (unsigned long)try_get_task_stack(p);
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if (!stack_page)
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return 0;
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frame.fp = thread_saved_fp(p);
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frame.sp = thread_saved_sp(p);
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frame.pc = thread_saved_pc(p);
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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frame.graph = p->curr_ret_stack;
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#endif
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stack_page = (unsigned long)task_stack_page(p);
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do {
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if (frame.sp < stack_page ||
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frame.sp >= stack_page + THREAD_SIZE ||
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unwind_frame(p, &frame))
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return 0;
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if (!in_sched_functions(frame.pc))
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return frame.pc;
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goto out;
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if (!in_sched_functions(frame.pc)) {
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ret = frame.pc;
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goto out;
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}
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} while (count ++ < 16);
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return 0;
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out:
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put_task_stack(p);
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return ret;
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}
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unsigned long arch_align_stack(unsigned long sp)
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@ -181,6 +181,9 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
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struct stack_trace_data data;
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struct stackframe frame;
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if (!try_get_task_stack(tsk))
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return;
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data.trace = trace;
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data.skip = trace->skip;
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@ -202,6 +205,8 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
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walk_stackframe(tsk, &frame, save_trace, &data);
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if (trace->nr_entries < trace->max_entries)
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trace->entries[trace->nr_entries++] = ULONG_MAX;
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put_task_stack(tsk);
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}
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void save_stack_trace(struct stack_trace *trace)
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@ -148,6 +148,9 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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if (!tsk)
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tsk = current;
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if (!try_get_task_stack(tsk))
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return;
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/*
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* Switching between stacks is valid when tracing current and in
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* non-preemptible context.
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@ -213,6 +216,8 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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stack + sizeof(struct pt_regs));
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}
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}
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put_task_stack(tsk);
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}
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void show_stack(struct task_struct *tsk, unsigned long *sp)
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