| Message ID | 1562820438-30328-1-git-send-email-zhenzhong.duan@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xen/pv: Fix a boot up hang triggered by int3 self test | expand |
Sorry for the noise, it looks description is wrong. This is not a double pop, but xen pv taking the path with create_gap=0, I'll send a v2. Zhenzhong On 2019/7/11 12:47, Zhenzhong Duan wrote: > Commit 7457c0da024b ("x86/alternatives: Add int3_emulate_call() > selftest") reveals a bug in XEN PV int3 assemble code. There is > a double pop of register R11 and RCX currupting the exception > frame, one in xen_int3 and the other in xen_xenint3. > > We see below hang at bootup: > > general protection fault: 0000 [#1] SMP NOPTI > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.2.0+ #6 > RIP: e030:int3_magic+0x0/0x7 > Call Trace: > alternative_instructions+0x3d/0x12e > check_bugs+0x7c9/0x887 > ?__get_locked_pte+0x178/0x1f0 > start_kernel+0x4ff/0x535 > ?set_init_arg+0x55/0x55 > xen_start_kernel+0x571/0x57a > > Fix it by removing xen_xenint3. > > Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: Juergen Gross <jgross@suse.com> > Cc: Stefano Stabellini <sstabellini@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Borislav Petkov <bp@alien8.de> > --- > arch/x86/include/asm/traps.h | 2 +- > arch/x86/xen/enlighten_pv.c | 2 +- > arch/x86/xen/xen-asm_64.S | 1 - > 3 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h > index 7d6f3f3..f2bd284 100644 > --- a/arch/x86/include/asm/traps.h > +++ b/arch/x86/include/asm/traps.h > @@ -40,7 +40,7 @@ > asmlinkage void xen_divide_error(void); > asmlinkage void xen_xennmi(void); > asmlinkage void xen_xendebug(void); > -asmlinkage void xen_xenint3(void); > +asmlinkage void xen_int3(void); > asmlinkage void xen_overflow(void); > asmlinkage void xen_bounds(void); > asmlinkage void xen_invalid_op(void); > diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c > index 4722ba2..2138d69 100644 > --- a/arch/x86/xen/enlighten_pv.c > +++ b/arch/x86/xen/enlighten_pv.c > @@ -596,7 +596,7 @@ struct trap_array_entry { > > static struct trap_array_entry trap_array[] = { > { debug, xen_xendebug, true }, > - { int3, xen_xenint3, true }, > + { int3, xen_int3, true }, > { double_fault, xen_double_fault, true }, > #ifdef CONFIG_X86_MCE > { machine_check, xen_machine_check, true }, > diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S > index 1e9ef0b..ebf610b 100644 > --- a/arch/x86/xen/xen-asm_64.S > +++ b/arch/x86/xen/xen-asm_64.S > @@ -32,7 +32,6 @@ xen_pv_trap divide_error > xen_pv_trap debug > xen_pv_trap xendebug > xen_pv_trap int3 > -xen_pv_trap xenint3 > xen_pv_trap xennmi > xen_pv_trap overflow > xen_pv_trap bounds
diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index 7d6f3f3..f2bd284 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -40,7 +40,7 @@ asmlinkage void xen_divide_error(void); asmlinkage void xen_xennmi(void); asmlinkage void xen_xendebug(void); -asmlinkage void xen_xenint3(void); +asmlinkage void xen_int3(void); asmlinkage void xen_overflow(void); asmlinkage void xen_bounds(void); asmlinkage void xen_invalid_op(void); diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 4722ba2..2138d69 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -596,7 +596,7 @@ struct trap_array_entry { static struct trap_array_entry trap_array[] = { { debug, xen_xendebug, true }, - { int3, xen_xenint3, true }, + { int3, xen_int3, true }, { double_fault, xen_double_fault, true }, #ifdef CONFIG_X86_MCE { machine_check, xen_machine_check, true }, diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index 1e9ef0b..ebf610b 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -32,7 +32,6 @@ xen_pv_trap divide_error xen_pv_trap debug xen_pv_trap xendebug xen_pv_trap int3 -xen_pv_trap xenint3 xen_pv_trap xennmi xen_pv_trap overflow xen_pv_trap bounds
Commit 7457c0da024b ("x86/alternatives: Add int3_emulate_call() selftest") reveals a bug in XEN PV int3 assemble code. There is a double pop of register R11 and RCX currupting the exception frame, one in xen_int3 and the other in xen_xenint3. We see below hang at bootup: general protection fault: 0000 [#1] SMP NOPTI CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.2.0+ #6 RIP: e030:int3_magic+0x0/0x7 Call Trace: alternative_instructions+0x3d/0x12e check_bugs+0x7c9/0x887 ?__get_locked_pte+0x178/0x1f0 start_kernel+0x4ff/0x535 ?set_init_arg+0x55/0x55 xen_start_kernel+0x571/0x57a Fix it by removing xen_xenint3. Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Juergen Gross <jgross@suse.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> --- arch/x86/include/asm/traps.h | 2 +- arch/x86/xen/enlighten_pv.c | 2 +- arch/x86/xen/xen-asm_64.S | 1 - 3 files changed, 2 insertions(+), 3 deletions(-)