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    Subject[tip:x86/asm] x86/dumpstack: Fix occasionally missing registers
    Commit-ID:  b0529becebde629ff6abf2afdca6def6824f4fa9
    Gitweb: http://git.kernel.org/tip/b0529becebde629ff6abf2afdca6def6824f4fa9
    Author: Josh Poimboeuf <jpoimboe@redhat.com>
    AuthorDate: Tue, 11 Jul 2017 10:33:40 -0500
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Tue, 18 Jul 2017 10:56:23 +0200

    x86/dumpstack: Fix occasionally missing registers

    If two consecutive stack frames have pt_regs, the oops dump code fails
    to print the second frame's registers. Fix that.

    Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Jiri Slaby <jslaby@suse.cz>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: live-patching@vger.kernel.org
    Fixes: 3b3fa11bc700 ("x86/dumpstack: Print any pt_regs found on the stack")
    Link: http://lkml.kernel.org/r/269c5c00c7d45c699f3dcea42a3a594c6cf7a9a3.1499786555.git.jpoimboe@redhat.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    arch/x86/kernel/dumpstack.c | 12 +++++++-----
    1 file changed, 7 insertions(+), 5 deletions(-)

    diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
    index dbce3cc..bd265a4 100644
    --- a/arch/x86/kernel/dumpstack.c
    +++ b/arch/x86/kernel/dumpstack.c
    @@ -94,6 +94,9 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
    if (stack_name)
    printk("%s <%s>\n", log_lvl, stack_name);

    + if (regs && on_stack(&stack_info, regs, sizeof(*regs)))
    + __show_regs(regs, 0);
    +
    /*
    * Scan the stack, printing any text addresses we find. At the
    * same time, follow proper stack frames with the unwinder.
    @@ -118,10 +121,8 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
    * Don't print regs->ip again if it was already printed
    * by __show_regs() below.
    */
    - if (regs && stack == &regs->ip) {
    - unwind_next_frame(&state);
    - continue;
    - }
    + if (regs && stack == &regs->ip)
    + goto next;

    if (stack == ret_addr_p)
    reliable = 1;
    @@ -144,6 +145,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
    if (!reliable)
    continue;

    +next:
    /*
    * Get the next frame from the unwinder. No need to
    * check for an error: if anything goes wrong, the rest
    @@ -153,7 +155,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,

    /* if the frame has entry regs, print them */
    regs = unwind_get_entry_regs(&state);
    - if (regs)
    + if (regs && on_stack(&stack_info, regs, sizeof(*regs)))
    __show_regs(regs, 0);
    }

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