From: Adrian Hunter <adrian.hunter@intel.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Leo Yan <leo.yan@linaro.org>, Jiri Olsa <jolsa@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH V7 02/15] perf/x86: Add support for perf text poke event for text_poke_bp_batch() callers
Date: Tue, 12 May 2020 15:19:09 +0300 [thread overview]
Message-ID: <20200512121922.8997-3-adrian.hunter@intel.com> (raw)
In-Reply-To: <20200512121922.8997-1-adrian.hunter@intel.com>
Add support for perf text poke event for text_poke_bp_batch() callers. That
includes jump labels. See comments for more details.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/kernel/alternative.c | 37 ++++++++++++++++++++++++++++++++++-
1 file changed, 36 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 7867dfb3963e..6082289879c1 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -3,6 +3,7 @@
#include <linux/module.h>
#include <linux/sched.h>
+#include <linux/perf_event.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/stringify.h>
@@ -947,6 +948,7 @@ struct text_poke_loc {
s32 rel32;
u8 opcode;
const u8 text[POKE_MAX_OPCODE_SIZE];
+ u8 old;
};
struct bp_patching_desc {
@@ -1115,8 +1117,10 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries
/*
* First step: add a int3 trap to the address that will be patched.
*/
- for (i = 0; i < nr_entries; i++)
+ for (i = 0; i < nr_entries; i++) {
+ tp[i].old = *(u8 *)text_poke_addr(&tp[i]);
text_poke(text_poke_addr(&tp[i]), &int3, INT3_INSN_SIZE);
+ }
text_poke_sync();
@@ -1124,14 +1128,45 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries
* Second step: update all but the first byte of the patched range.
*/
for (do_sync = 0, i = 0; i < nr_entries; i++) {
+ u8 old[POKE_MAX_OPCODE_SIZE] = { tp[i].old, };
int len = text_opcode_size(tp[i].opcode);
if (len - INT3_INSN_SIZE > 0) {
+ memcpy(old + INT3_INSN_SIZE,
+ text_poke_addr(&tp[i]) + INT3_INSN_SIZE,
+ len - INT3_INSN_SIZE);
text_poke(text_poke_addr(&tp[i]) + INT3_INSN_SIZE,
(const char *)tp[i].text + INT3_INSN_SIZE,
len - INT3_INSN_SIZE);
do_sync++;
}
+
+ /*
+ * Emit a perf event to record the text poke, primarily to
+ * support Intel PT decoding which must walk the executable code
+ * to reconstruct the trace. The flow up to here is:
+ * - write INT3 byte
+ * - IPI-SYNC
+ * - write instruction tail
+ * At this point the actual control flow will be through the
+ * INT3 and handler and not hit the old or new instruction.
+ * Intel PT outputs FUP/TIP packets for the INT3, so the flow
+ * can still be decoded. Subsequently:
+ * - emit RECORD_TEXT_POKE with the new instruction
+ * - IPI-SYNC
+ * - write first byte
+ * - IPI-SYNC
+ * So before the text poke event timestamp, the decoder will see
+ * either the old instruction flow or FUP/TIP of INT3. After the
+ * text poke event timestamp, the decoder will see either the
+ * new instruction flow or FUP/TIP of INT3. Thus decoders can
+ * use the timestamp as the point at which to modify the
+ * executable code.
+ * The old instruction is recorded so that the event can be
+ * processed forwards or backwards.
+ */
+ perf_event_text_poke(text_poke_addr(&tp[i]), old, len,
+ tp[i].text, len);
}
if (do_sync) {
--
2.17.1
next prev parent reply other threads:[~2020-05-12 12:19 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 12:19 [PATCH V7 00/15] perf/x86: Add perf text poke events Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 01/15] perf: Add perf text poke event Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` Adrian Hunter [this message]
2020-06-16 12:21 ` [tip: perf/core] perf/x86: Add support for perf text poke event for text_poke_bp_batch() callers tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 03/15] kprobes: Add symbols for kprobe insn pages Adrian Hunter
2020-05-27 17:43 ` Peter Zijlstra
2020-05-28 0:31 ` Masami Hiramatsu
2020-05-28 8:00 ` Adrian Hunter
2020-05-28 8:00 ` [PATCH V8 " Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-28 0:25 ` [PATCH V7 03/15] " Masami Hiramatsu
2020-05-12 12:19 ` [PATCH V7 04/15] kprobes: Add perf ksymbol events " Adrian Hunter
2020-05-27 16:17 ` Peter Zijlstra
2020-05-27 17:20 ` Peter Zijlstra
2020-05-28 7:58 ` Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 05/15] perf/x86: Add perf text poke events for kprobes Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 06/15] ftrace: Add symbols for ftrace trampolines Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 07/15] ftrace: Add perf ksymbol events " Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 08/15] ftrace: Add perf text poke " Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 09/15] perf kcore_copy: Fix module map when there are no modules loaded Adrian Hunter
2020-05-27 15:44 ` Arnaldo Carvalho de Melo
2020-05-12 12:19 ` [PATCH V7 10/15] perf evlist: Disable 'immediate' events last Adrian Hunter
2020-05-27 15:44 ` Arnaldo Carvalho de Melo
2020-05-12 12:19 ` [PATCH V7 11/15] perf tools: Add support for PERF_RECORD_TEXT_POKE Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 12/15] perf tools: Add support for PERF_RECORD_KSYMBOL_TYPE_OOL Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 13/15] perf intel-pt: Add support for text poke events Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 14/15] perf script: Add option --show-text-poke-events Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 15/15] perf script: Show text poke address symbol Adrian Hunter
2020-05-20 1:38 ` Arnaldo Carvalho de Melo
2020-07-10 11:34 ` Arnaldo Carvalho de Melo
2020-07-10 11:38 ` Adrian Hunter
2020-05-17 13:16 ` [PATCH V7 00/15] perf/x86: Add perf text poke events Adrian Hunter
2020-05-20 1:40 ` Arnaldo Carvalho de Melo
2020-05-20 15:56 ` Peter Zijlstra
2020-05-27 15:47 ` Arnaldo Carvalho de Melo
2020-05-27 15:54 ` Peter Zijlstra
2020-07-08 11:55 ` Adrian Hunter
2020-07-08 12:34 ` Arnaldo Carvalho de Melo
2020-07-10 11:43 ` Arnaldo Carvalho de Melo
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