88b604263f
current_stack_pointer() simply returns current value of %r15. If current_stack_pointer() caller allocates stack (which is the case in unwind code) %r15 points to a stack frame allocated for callees, meaning current_stack_pointer() caller (e.g. stack_trace_save) will end up in the stacktrace. This is not expected by stack_trace_save*() callers and causes problems. current_frame_address() on the other hand returns function stack frame address, which matches %r15 upon function invocation. Using it in get_stack_pointer() makes it more aligned with x86 implementation (according to BACKTRACE_SELF_TEST output) and meets stack_trace_save*() caller's expectations, notably KCSAN. Also make sure unwind_start is always inlined. Reported-by: Nathan Chancellor <nathan@kernel.org> Suggested-by: Marco Elver <elver@google.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Tested-by: Marco Elver <elver@google.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/patch.git-04dd26be3043.your-ad-here.call-01630504868-ext-6188@work.hours Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
84 lines
2.8 KiB
C
84 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_S390_UNWIND_H
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#define _ASM_S390_UNWIND_H
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#include <linux/sched.h>
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#include <linux/ftrace.h>
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#include <asm/ptrace.h>
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#include <asm/stacktrace.h>
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/*
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* To use the stack unwinder it has to be initialized with unwind_start.
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* There four combinations for task and regs:
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* 1) task==NULL, regs==NULL: the unwind starts for the task that is currently
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* running, sp/ip picked up from the CPU registers
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* 2) task==NULL, regs!=NULL: the unwind starts from the sp/ip found in
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* the struct pt_regs of an interrupt frame for the current task
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* 3) task!=NULL, regs==NULL: the unwind starts for an inactive task with
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* the sp picked up from task->thread.ksp and the ip picked up from the
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* return address stored by __switch_to
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* 4) task!=NULL, regs!=NULL: the sp/ip are picked up from the interrupt
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* frame 'regs' of a inactive task
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* If 'first_frame' is not zero unwind_start skips unwind frames until it
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* reaches the specified stack pointer.
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* The end of the unwinding is indicated with unwind_done, this can be true
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* right after unwind_start, e.g. with first_frame!=0 that can not be found.
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* unwind_next_frame skips to the next frame.
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* Once the unwind is completed unwind_error() can be used to check if there
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* has been a situation where the unwinder could not correctly understand
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* the tasks call chain.
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*/
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struct unwind_state {
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struct stack_info stack_info;
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unsigned long stack_mask;
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struct task_struct *task;
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struct pt_regs *regs;
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unsigned long sp, ip;
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int graph_idx;
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bool reliable;
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bool error;
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};
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void __unwind_start(struct unwind_state *state, struct task_struct *task,
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struct pt_regs *regs, unsigned long first_frame);
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bool unwind_next_frame(struct unwind_state *state);
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unsigned long unwind_get_return_address(struct unwind_state *state);
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static inline bool unwind_done(struct unwind_state *state)
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{
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return state->stack_info.type == STACK_TYPE_UNKNOWN;
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}
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static inline bool unwind_error(struct unwind_state *state)
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{
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return state->error;
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}
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static __always_inline void unwind_start(struct unwind_state *state,
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struct task_struct *task,
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struct pt_regs *regs,
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unsigned long first_frame)
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{
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task = task ?: current;
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first_frame = first_frame ?: get_stack_pointer(task, regs);
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__unwind_start(state, task, regs, first_frame);
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}
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static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
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{
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return unwind_done(state) ? NULL : state->regs;
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}
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#define unwind_for_each_frame(state, task, regs, first_frame) \
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for (unwind_start(state, task, regs, first_frame); \
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!unwind_done(state); \
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unwind_next_frame(state))
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static inline void unwind_init(void) {}
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static inline void unwind_module_init(struct module *mod, void *orc_ip,
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size_t orc_ip_size, void *orc,
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size_t orc_size) {}
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#endif /* _ASM_S390_UNWIND_H */
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