From 548c3050ea8d16997ae27f9e080a8338a606fc93 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 21 Nov 2017 20:43:56 -0800 Subject: [PATCH] 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 Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org Fixes: 8a9949bc71a7 ("x86/xen/64: Rearrange the SYSCALL entries") Link: http://lkml.kernel.org/r/9150aac013b7b95d62c2336751d5b6e91d2722aa.1511325444.git.luto@kernel.org Signed-off-by: Ingo Molnar --- 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 a2b30ec69497..5063ed1214dd 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. -- GitLab