Commit-ID: 548c3050ea8d16997ae27f9e080a8338a606fc93
Gitweb: https://git.kernel.org/tip/548c3050ea8d16997ae27f9e080a8338a606fc93
Author: Andy Lutomirski <l...@kernel.org>
AuthorDate: Tue, 21 Nov 2017 20:43:56 -0800
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Wed, 22 Nov 2017 06:35:48 +0100
x86/entry/64: Fix entry_SYSCALL_64_after_hwframe() IRQ tracing
When I added entry_SYSCALL_64_after_hwframe(), I left TRACE_IRQS_OFF
before it. This means that users of entry_SYSCALL_64_after_hwframe()
were responsible for invoking TRACE_IRQS_OFF, and the one and only
user (Xen, added in the same commit) got it wrong.
I think this would manifest as a warning if a Xen PV guest with
CONFIG_DEBUG_LOCKDEP=y were used with context tracking. (The
context tracking bit is to cause lockdep to get invoked before we
turn IRQs back on.) I haven't tested that for real yet because I
can't get a kernel configured like that to boot at all on Xen PV.
Move TRACE_IRQS_OFF below the label.
Signed-off-by: Andy Lutomirski <l...@kernel.org>
Cc: Boris Ostrovsky <boris.ostrov...@oracle.com>
Cc: Borislav Petkov <bpet...@suse.de>
Cc: Brian Gerst <brge...@gmail.com>
Cc: Dave Hansen <dave.han...@intel.com>
Cc: Josh Poimboeuf <jpoim...@redhat.com>
Cc: Juergen Gross <jgr...@suse.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: sta...@vger.kernel.org
Fixes: 8a9949bc71a7 ("x86/xen/64: Rearrange the SYSCALL entries")
Link:
http://lkml.kernel.org/r/9150aac013b7b95d62c2336751d5b6e91d2722aa.1511325444.git.l...@kernel.org
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
arch/x86/entry/entry_64.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index a2b30ec..5063ed1 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -148,8 +148,6 @@ ENTRY(entry_SYSCALL_64)
movq %rsp, PER_CPU_VAR(rsp_scratch)
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
- TRACE_IRQS_OFF
-
/* Construct struct pt_regs on stack */
pushq $__USER_DS /* pt_regs->ss */
pushq PER_CPU_VAR(rsp_scratch) /* pt_regs->sp */
@@ -170,6 +168,8 @@ GLOBAL(entry_SYSCALL_64_after_hwframe)
sub $(6*8), %rsp /* pt_regs->bp, bx, r12-15 not
saved */
UNWIND_HINT_REGS extra=0
+ TRACE_IRQS_OFF
+
/*
* If we need to do entry work or if we guess we'll need to do
* exit work, go straight to the slow path.
