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SubjectRe: [PATCH FIX] traps: x86: correct copy/paste bug: a trap is a GATE_TRAP

* Alexander van Heukelum <heukelum@mailshack.com> wrote:

> > > > This series unifies traps_32.c and traps_64.c.
> > >
> > > wow, very nice! I've applied them to tip/x86/traps:
> > >
> > > f58f3d5: traps: x86: finalize unification of traps.c
> > > bf395d6: traps: x86: make traps_32.c and traps_64.c equal
> > > f156f35: traps: x86: various noop-changes preparing for unification of traps_xx.c
> > > 70cfe30: traps: x86_64: use task_pid_nr(tsk) instead of tsk->pid in do_general_protection
> > > dc89ce0: traps: i386: expand clear_mem_error and remove from mach_traps.h
> > > 6f8063f: traps: x86_64: make io_check_error equal to the one on i386
> > > d025445: traps: i386: use preempt_conditional_sti/cli in do_int3
> > > 2180afa: traps: x86_64: make math_state_restore more like i386
> > > 686cc4a: traps: x86: converge trap_init functions
> >
> > -tip testing found a spontaneus reboot bug on two 32-bit systems (one
> > Intel and one AMD testbox), and i've bisected it down to:
> >
> > | 686cc4a0c1ca92bffbc22a897c3b433dadbbf444 is first bad commit
> > | commit 686cc4a0c1ca92bffbc22a897c3b433dadbbf444
> > | Author: Alexander van Heukelum <heukelum@fastmail.fm>
> > | Date: Fri Oct 3 22:00:32 2008 +0200
> > |
> > | traps: x86: converge trap_init functions
> >
> > config attached. The bisection log:
> >
> > # bad: [a229a9da] Merge branch 'timers/urgent'
> > # good: [27de5e39] Merge branch 'out-of-tree'
> > # good: [8e9cb9db] Merge branch 'tracing/ring-buffer'
> > # bad: [70cfe30f] traps: x86_64: use task_pid_nr(tsk) instead of tsk
> > # bad: [d0254456] traps: i386: use preempt_conditional_sti/cli in do
> > # bad: [2180afaf] traps: x86_64: make math_state_restore more like i
> > # bad: [686cc4a0] traps: x86: converge trap_init functions
> >
> > so i've excluded these commits from tip/master for now.
> >
> > there's no serial log entry visible - the spontaneous reboot happens at
> > around when we hit user-space.
> >
> > I suspect syscall entry setup might be borked - the stack frames of call
> > gates versus interrupt gates are different and it's easy to make a small
> > mistake there with such effects.
> >
> > Ingo
>
> *blush*
>
> You were so right. I have no idea how this has slipped
> through testing. Could you see if this on top of the
> traps branch makes things go again? I'll get you some
> replacement patches to make the whole thing bisectable
> again.

> static inline void set_system_trap_gate(unsigned int n, void *addr)
> {
> BUG_ON((unsigned)n > 0xFF);
> - _set_gate(n, GATE_INTERRUPT, addr, 0x3, 0, __KERNEL_CS);
> + _set_gate(n, GATE_TRAP, addr, 0x3, 0, __KERNEL_CS);
> }

indeed, that would explain it :)

i've added your delta fix, and will propagate/squash it back to 1/9 if
it tests out fine. (it's worth having this series fully bisectable)

Ingo


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