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From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Clark Williams <williams@redhat.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Andi Kleen <ak@linux.intel.com>,
	Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: [PATCH 15/24] perf script brstackinsn: Fix recovery from LBR/binary mismatch
Date: Tue,  1 Oct 2019 08:12:07 -0300	[thread overview]
Message-ID: <20191001111216.7208-16-acme@kernel.org> (raw)
In-Reply-To: <20191001111216.7208-1-acme@kernel.org>

From: Andi Kleen <ak@linux.intel.com>

When the LBR data and the instructions in a binary do not match the loop
printing instructions could get confused and print a long stream of
bogus <bad> instructions.

The problem was that if the instruction decoder cannot decode an
instruction it ilen wasn't initialized, so the loop going through the
basic block would continue with the previous value.

Harden the code to avoid such problems:

- Make sure ilen is always freshly initialized and is 0 for bad
  instructions.

- Do not overrun the code buffer while printing instructions

- Print a warning message if the final jump is not on an instruction
  boundary.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20190927233546.11533-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-script.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 286fc70d7402..67be8d31afab 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1063,7 +1063,7 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample,
 			continue;
 
 		insn = 0;
-		for (off = 0;; off += ilen) {
+		for (off = 0; off < (unsigned)len; off += ilen) {
 			uint64_t ip = start + off;
 
 			printed += ip__fprintf_sym(ip, thread, x.cpumode, x.cpu, &lastsym, attr, fp);
@@ -1074,6 +1074,7 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample,
 					printed += print_srccode(thread, x.cpumode, ip);
 				break;
 			} else {
+				ilen = 0;
 				printed += fprintf(fp, "\t%016" PRIx64 "\t%s\n", ip,
 						   dump_insn(&x, ip, buffer + off, len - off, &ilen));
 				if (ilen == 0)
@@ -1083,6 +1084,8 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample,
 				insn++;
 			}
 		}
+		if (off != (unsigned)len)
+			printed += fprintf(fp, "\tmismatch of LBR data and executable\n");
 	}
 
 	/*
@@ -1123,6 +1126,7 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample,
 		goto out;
 	}
 	for (off = 0; off <= end - start; off += ilen) {
+		ilen = 0;
 		printed += fprintf(fp, "\t%016" PRIx64 "\t%s\n", start + off,
 				   dump_insn(&x, start + off, buffer + off, len - off, &ilen));
 		if (ilen == 0)
-- 
2.21.0

  parent reply	other threads:[~2019-10-01 11:12 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-01 11:11 [GIT PULL] perf/urgent improvements and fixes Arnaldo Carvalho de Melo
2019-10-01 11:11 ` [PATCH 01/24] libsubcmd: Make _FORTIFY_SOURCE defines dependent on the feature Arnaldo Carvalho de Melo
2019-10-01 11:11 ` [PATCH 02/24] perf tests: Avoid raising SEGV using an obvious NULL dereference Arnaldo Carvalho de Melo
2019-10-01 11:11 ` [PATCH 03/24] perf docs: Allow man page date to be specified Arnaldo Carvalho de Melo
2019-10-01 11:11 ` [PATCH 04/24] tools headers uapi: Sync drm/i915_drm.h with the kernel sources Arnaldo Carvalho de Melo
2019-10-01 11:11 ` [PATCH 05/24] tools headers uapi: Sync asm-generic/mman-common.h with the kernel Arnaldo Carvalho de Melo
2019-10-01 11:11 ` [PATCH 06/24] tools headers uapi: Sync linux/usbdevice_fs.h with the kernel sources Arnaldo Carvalho de Melo
2019-10-01 13:59   ` Alan Stern
2019-10-01 19:23     ` Arnaldo Carvalho de Melo
2019-10-01 11:11 ` [PATCH 07/24] tools headers uapi: Sync linux/fs.h " Arnaldo Carvalho de Melo
2019-10-01 18:45   ` Eric Biggers
2019-10-01 18:57     ` Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 08/24] tools headers kvm: Sync kvm headers " Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 09/24] perf llvm: Don't access out-of-scope array Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 10/24] perf vendor events s390: Add JSON transaction for machine type 8561 Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 11/24] perf vendor events s390: Use s390 machine name instead of " Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 12/24] perf map: Fix overlapped map handling Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 13/24] perf inject jit: Fix JIT_CODE_MOVE filename Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 14/24] perf docs: Correct and clarify jitdump spec Arnaldo Carvalho de Melo
2019-10-01 11:12 ` Arnaldo Carvalho de Melo [this message]
2019-10-01 11:12 ` [PATCH 16/24] perf jevents: Fix period for Intel fixed counters Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 17/24] perf tools: Propagate get_cpuid() error Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 18/24] perf evsel: Fall back to global 'perf_env' in perf_evsel__env() Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 19/24] perf annotate: Propagate perf_env__arch() error Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 20/24] perf annotate: Fix the signedness of failure returns Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 21/24] perf annotate: Propagate the symbol__annotate() error return Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 22/24] perf annotate: Fix arch specific ->init() failure errors Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 23/24] perf annotate: Return appropriate error code for allocation failures Arnaldo Carvalho de Melo
2019-10-01 11:12 ` [PATCH 24/24] perf annotate: Don't return -1 for error when doing BPF disassembly Arnaldo Carvalho de Melo
2019-10-07 13:16 ` [GIT PULL] perf/urgent improvements and fixes Ingo Molnar

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