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a9cdbe72c4
The show_regs_safe() logic is wrong. When there's an iret stack frame, it prints the entire pt_regs -- most of which is random stack data -- instead of just the five registers at the end. show_regs_safe() is also poorly named: the on_stack() checks aren't for safety. Rename the function to show_regs_if_on_stack() and add a comment to explain why the checks are needed. These issues were introduced with the "partial register dump" feature of the following commit:b02fcf9ba1("x86/unwinder: Handle stack overflows more gracefully") That patch had gone through a few iterations of development, and the above issues were artifacts from a previous iteration of the patch where 'regs' pointed directly to the iret frame rather than to the (partially empty) pt_regs. Tested-by: Alexander Tsoy <alexander@tsoy.me> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Toralf Förster <toralf.foerster@gmx.de> Cc: stable@vger.kernel.org Fixes:b02fcf9ba1("x86/unwinder: Handle stack overflows more gracefully") Link: http://lkml.kernel.org/r/5b05b8b344f59db2d3d50dbdeba92d60f2304c54.1514736742.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
120 lines
2.9 KiB
C
120 lines
2.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_UNWIND_H
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#define _ASM_X86_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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#define IRET_FRAME_OFFSET (offsetof(struct pt_regs, ip))
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#define IRET_FRAME_SIZE (sizeof(struct pt_regs) - IRET_FRAME_OFFSET)
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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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int graph_idx;
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bool error;
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#if defined(CONFIG_UNWINDER_ORC)
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bool signal, full_regs;
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unsigned long sp, bp, ip;
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struct pt_regs *regs;
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#elif defined(CONFIG_UNWINDER_FRAME_POINTER)
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bool got_irq;
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unsigned long *bp, *orig_sp, ip;
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struct pt_regs *regs;
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#else
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unsigned long *sp;
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#endif
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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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unsigned long *unwind_get_return_address_ptr(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 inline
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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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{
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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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#if defined(CONFIG_UNWINDER_ORC) || defined(CONFIG_UNWINDER_FRAME_POINTER)
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/*
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* If 'partial' returns true, only the iret frame registers are valid.
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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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bool *partial)
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{
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if (unwind_done(state))
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return NULL;
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if (partial) {
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#ifdef CONFIG_UNWINDER_ORC
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*partial = !state->full_regs;
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#else
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*partial = false;
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#endif
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}
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return state->regs;
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}
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#else
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static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
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bool *partial)
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{
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return NULL;
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}
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#endif
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#ifdef CONFIG_UNWINDER_ORC
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void unwind_init(void);
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void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
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void *orc, size_t orc_size);
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#else
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static inline void unwind_init(void) {}
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static inline
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void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
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void *orc, size_t orc_size) {}
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#endif
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/*
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* This disables KASAN checking when reading a value from another task's stack,
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* since the other task could be running on another CPU and could have poisoned
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* the stack in the meantime.
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*/
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#define READ_ONCE_TASK_STACK(task, x) \
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({ \
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unsigned long val; \
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if (task == current) \
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val = READ_ONCE(x); \
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else \
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val = READ_ONCE_NOCHECK(x); \
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val; \
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})
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static inline bool task_on_another_cpu(struct task_struct *task)
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{
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#ifdef CONFIG_SMP
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return task != current && task->on_cpu;
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#else
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return false;
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#endif
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}
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#endif /* _ASM_X86_UNWIND_H */
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