From 7cb3e16466fc1f9cb5724da048d0e13613bb84a2 Mon Sep 17 00:00:00 2001
From: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Date: Sun, 14 Jul 2019 17:15:32 +0800
Subject: 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>
---
 arch/x86/xen/xen-asm_64.S | 1 -
 1 file changed, 1 deletion(-)

(limited to 'arch/x86/xen/xen-asm_64.S')

diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index 417b339e5c8e..3a6feed76dfc 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -30,7 +30,6 @@ 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
-- 
cgit v1.2.3


From e8113c362adcb8735c81f80cf24d781708047ce1 Mon Sep 17 00:00:00 2001
From: Andrea Righi <righi.andrea@gmail.com>
Date: Mon, 10 Dec 2018 16:12:57 +0100
Subject: kprobes/x86/xen: blacklist non-attachable xen interrupt functions

[ Upstream commit bf9445a33ae6ac2f0822d2f1ce1365408387d568 ]

Blacklist symbols in Xen probe-prohibited areas, so that user can see
these prohibited symbols in debugfs.

See also: a50480cb6d61.

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/xen/xen-asm_64.S | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'arch/x86/xen/xen-asm_64.S')

diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index 3a6feed76dfc..a93d8a7cef26 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -12,6 +12,7 @@
 #include <asm/segment.h>
 #include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
+#include <asm/asm.h>
 
 #include <xen/interface/xen.h>
 
@@ -24,6 +25,7 @@ ENTRY(xen_\name)
 	pop %r11
 	jmp  \name
 END(xen_\name)
+_ASM_NOKPROBE(xen_\name)
 .endm
 
 xen_pv_trap divide_error
-- 
cgit v1.2.3