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From: tip-bot for Peter Zijlstra on 25 May 2010 04:10
Commit-ID: 23ef672d1e8236e6fe606a39963ba2d576972d84
Gitweb: http://git.kernel.org/tip/23ef672d1e8236e6fe606a39963ba2d576972d84
Author: Peter Zijlstra <peterz(a)infradead.org>
AuthorDate: Sun, 23 May 2010 20:16:27 +0200
Committer: Ingo Molnar <mingo(a)elte.hu>
CommitDate: Tue, 25 May 2010 09:02:08 +0200

perf, trace: Fix IRQ-disable removal from perf/tracepoint interaction

On x86 perf_arch_fetch_caller_regs() stores pt_regs::flags, which is the
same as used in local_save_flags().

So to avoid another local_save_flags() for the ftrace code, I wanted to
reuse it, and totally forgot the !x86 side of things.

[ Possibly we could remove the local_save_flags() from the
perf_arch_fetch_caller_regs() as I'm not sure we actually use
pt_regs::flags (Frederic?) and leave the ftrace thing to use
local_save_flags(). ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl>
Acked-by: Paul Mackerras <paulus(a)samba.org>
Cc: Arnaldo Carvalho de Melo <acme(a)redhat.com>
Cc: Frederic Weisbecker <fweisbec(a)gmail.com>
Cc: Mike Galbraith <efault(a)gmx.de>
Cc: Steven Rostedt <rostedt(a)goodmis.org>
LKML-Reference: <20100524042958.GA10628(a)drongo>
Signed-off-by: Ingo Molnar <mingo(a)elte.hu>
---
arch/x86/kernel/cpu/perf_event.c | 1 -
kernel/trace/trace_event_perf.c | 4 +++-
2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index fd4db0d..856aeeb 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1717,7 +1717,6 @@ 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);
}

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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