linux-kernel - [tip:perf/core] perf, trace: Fix !x86 build bug

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Date:	Tue, 25 May 2010 09:30:38 GMT
From:	tip-bot for Peter Zijlstra <peterz@...radead.org>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com,
	mingo@...hat.com, a.p.zijlstra@...llo.nl, peterz@...radead.org,
	tglx@...utronix.de, mingo@...e.hu
Subject: [tip:perf/core] perf, trace: Fix !x86 build bug

Commit-ID:  87f44bbc246c5244c76a701f8eefba7788bce64a
Gitweb:     http://git.kernel.org/tip/87f44bbc246c5244c76a701f8eefba7788bce64a
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Tue, 25 May 2010 11:02:55 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Tue, 25 May 2010 11:28:49 +0200

perf, trace: Fix !x86 build bug

Patch b7e2ecef92 (perf, trace: Optimize tracepoints by removing
IRQ-disable from perf/tracepoint interaction) made the
unfortunate mistake of assuming the world is x86 only, correct
this.

The problem was that perf_fetch_caller_regs() did
local_save_flags() into regs->flags, and I re-used that to
remove another local_save_flags(), forgetting !x86 doesn't have
regs->flags.

Do the reverse, remove the local_save_flags() from
perf_fetch_caller_regs() and let the ftrace site do the
local_save_flags() instead.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Acked-by: Paul Mackerras <paulus@...ba.org>
Cc: acme@...hat.com
Cc: efault@....de
Cc: fweisbec@...il.com
Cc: rostedt@...dmis.org
LKML-Reference: <1274778175.5882.623.camel@...ns>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/kernel/cpu/perf_event.c |    6 +++++-
 kernel/trace/trace_event_perf.c  |    4 +++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index fd4db0d..c775860 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1717,7 +1717,11 @@ void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int ski
 	 */
 	regs->bp = rewind_frame_pointer(skip + 1);
 	regs->cs = __KERNEL_CS;
-	local_save_flags(regs->flags);
+	/*
+	 * We abuse bit 3 to pass exact information, see perf_misc_flags
+	 * and the comment with PERF_EFLAGS_EXACT.
+	 */
+	regs->flags = 0;
 }
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 26b8607..cb6f365 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -157,6 +157,7 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
 				       struct pt_regs *regs, int *rctxp)
 {
 	struct trace_entry *entry;
+	unsigned long flags;
 	char *raw_data;
 	int pc;
 
@@ -174,7 +175,8 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
 	memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
 
 	entry = (struct trace_entry *)raw_data;
-	tracing_generic_entry_update(entry, regs->flags, pc);
+	local_save_flags(flags);
+	tracing_generic_entry_update(entry, flags, pc);
 	entry->type = type;
 
 	return raw_data;
--
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