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| author | Zhenzhong Duan <zhenzhong.duan@oracle.com> | 2019-07-14 17:15:32 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-08-06 19:08:13 +0200 |
| commit | 308f2134d0c5cd85dc9489cadb86ad1982f67eba (patch) | |
| tree | 82940550741f52689fff360a4c9526278731a00b /arch/x86/entry/entry_64.S | |
| parent | b8a98fff64deffe441901b8d7e2b8f6127c68e9e (diff) | |
| download | linux-stable-308f2134d0c5cd85dc9489cadb86ad1982f67eba.tar.gz linux-stable-308f2134d0c5cd85dc9489cadb86ad1982f67eba.tar.bz2 linux-stable-308f2134d0c5cd85dc9489cadb86ad1982f67eba.zip | |
xen/pv: Fix a boot up hang revealed by int3 self test
[ Upstream commit b23e5844dfe78a80ba672793187d3f52e4b528d7 ]
Commit 7457c0da024b ("x86/alternatives: Add int3_emulate_call()
selftest") is used to ensure there is a gap setup in int3 exception stack
which could be used for inserting call return address.
This gap is missed in XEN PV int3 exception entry path, then below panic
triggered:
[ 0.772876] general protection fault: 0000 [#1] SMP NOPTI
[ 0.772886] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.2.0+ #11
[ 0.772893] RIP: e030:int3_magic+0x0/0x7
[ 0.772905] RSP: 3507:ffffffff82203e98 EFLAGS: 00000246
[ 0.773334] Call Trace:
[ 0.773334] alternative_instructions+0x3d/0x12e
[ 0.773334] check_bugs+0x7c9/0x887
[ 0.773334] ? __get_locked_pte+0x178/0x1f0
[ 0.773334] start_kernel+0x4ff/0x535
[ 0.773334] ? set_init_arg+0x55/0x55
[ 0.773334] xen_start_kernel+0x571/0x57a
For 64bit PV guests, Xen's ABI enters the kernel with using SYSRET, with
%rcx/%r11 on the stack. To convert back to "normal" looking exceptions,
the xen thunks do 'xen_*: pop %rcx; pop %r11; jmp *'.
E.g. Extracting 'xen_pv_trap xenint3' we have:
xen_xenint3:
pop %rcx;
pop %r11;
jmp xenint3
As xenint3 and int3 entry code are same except xenint3 doesn't generate
a gap, we can fix it by using int3 and drop useless xenint3.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Andy Lutomirski <luto@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>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/x86/entry/entry_64.S')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 8dbca86c249b..5c033dc0c2c7 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1171,7 +1171,6 @@ idtentry stack_segment do_stack_segment has_error_code=1 #ifdef CONFIG_XEN_PV idtentry xennmi do_nmi has_error_code=0 idtentry xendebug do_debug has_error_code=0 -idtentry xenint3 do_int3 has_error_code=0 #endif idtentry general_protection do_general_protection has_error_code=1 |