| Message ID | 20230714084349.31567-1-tianruidong@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RESEND] coresight: tmc: Explicit type conversions to prevent integer overflow | expand |
Hi James, Sorry, some local patch caused inaccurate information. Please allow me to reintroduce the question: If you use perf with 1G AUX buffer, you can get 1G perf data. Perf workload is kernel build here: perf record -C 0 -m ,1G -e cs_etm// taskset -c 0 make [ perf record: Captured and wrote 1025.557 MB perf.data ] But if you use 2G AUX buffer, perf was executed unexpectedly： perf record -C 0 -m ,2G -e cs_etm// taskset -c 0 make [ perf record: Captured and wrote 2.615 MB perf.data ] There are just 2.615 MB perf data rather than 2G, if you probe function "tmc_alloc_etr_buf" in coresight_tmc module, you can find some clues: perf probe -m coresight_tmc "tmc_alloc_etr_buf size:s64" perf record -e probe:tmc_alloc_etr_buf -aR -- perf record -C 0 -m ,2G -e cs_etm// -o cs.data taskset -c 0 make perf script perf 118267 [064] 4640.324670: probe:tmc_alloc_etr_buf: (ffff80007a9dce60) size_s64=-2147483648 perf 118267 [064] 4640.324681: probe:tmc_alloc_etr_buf: (ffff80007a9dce60) size_s64=1048576 It's pretty obvious what's going on here. The first call of tmc_alloc_etr_buf in alloc_etr_buf was failed because of overflow, the second call of tmc_alloc_etr_buf just alloc 1M AUX buffer which is default ETR buffer size rather than 2G. That is why we can just get 2.615MB ( 1M AUX data + perf header ). It is necessary to check the conversion from int to s64 in coresight_tmc driver. The issue[1] also exists in coresight/perf, but it's different from this topic. [1]: https://lore.kernel.org/bpf/20230711014120.53461-1-xueshuai@linux.alibaba.com/ Thanks Ruidong On 2023/7/24 23:38, James Clark wrote: > > On 14/07/2023 09:43, Ruidong Tian wrote: >> Perf cs_etm session will failed when AUX buffer > 1G. >> >> perf record -C 0 -m ,2G -e cs_etm// -- taskset -c 0 ls >> failed to mmap with 12 (Cannot allocate memory) >> >> In coresight tmc driver, "nr_pages << PAGE_SHIFT" will overflow when >> nr_pages >= 0x80000(correspond to 1G AUX buffer). Explicit convert nr_pages >> to 64 bit to avoid overflow. >> > Hi Ruidong, > > I couldn't reproduce this exact issue with the error message in the > commit message. Is it not another manifestation related to this change > [1]? I don't actually get any error message, but I was able to get a > warning in dmesg even with [1] applied. > > Does the overflow not result in a successful session but with the wrong > buffer size? > > I think the change makes sense, but maybe we also need a check for > MAX_ORDER because I can trigger the same WARN_ON from [1]. Or maybe I'm > a bit confused because of the other change and not being able to > reproduce this exactly coming at the same time. > > [1]: > https://lore.kernel.org/bpf/20230711014120.53461-1-xueshuai@linux.alibaba.com/ > > Thanks > James > >> Signed-off-by: Ruidong Tian <tianruidong@linux.alibaba.com> >> --- >> drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 +- >> drivers/hwtracing/coresight/coresight-tmc.h | 2 +- >> 2 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c >> index 766325de0e29..1425ecd1cf78 100644 >> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c >> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c >> @@ -1267,7 +1267,7 @@ alloc_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event, >> * than the size requested via sysfs. >> */ >> if ((nr_pages << PAGE_SHIFT) > drvdata->size) { >> - etr_buf = tmc_alloc_etr_buf(drvdata, (nr_pages << PAGE_SHIFT), >> + etr_buf = tmc_alloc_etr_buf(drvdata, ((ssize_t)nr_pages << PAGE_SHIFT), >> 0, node, NULL); >> if (!IS_ERR(etr_buf)) >> goto done; >> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h >> index b97da39652d2..0ee48c5ba764 100644 >> --- a/drivers/hwtracing/coresight/coresight-tmc.h >> +++ b/drivers/hwtracing/coresight/coresight-tmc.h >> @@ -325,7 +325,7 @@ ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table, >> static inline unsigned long >> tmc_sg_table_buf_size(struct tmc_sg_table *sg_table) >> { >> - return sg_table->data_pages.nr_pages << PAGE_SHIFT; >> + return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT; >> } >> >> struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
On 02/08/2023 13:25, Ruidong Tian wrote: > Hi James, > > Sorry, some local patch caused inaccurate information. Please allow me > to reintroduce the question: > > If you use perf with 1G AUX buffer, you can get 1G perf data. Perf > workload is kernel build here: > > perf record -C 0 -m ,1G -e cs_etm// taskset -c 0 make > > [ perf record: Captured and wrote 1025.557 MB perf.data ] > > But if you use 2G AUX buffer, perf was executed unexpectedly： > > perf record -C 0 -m ,2G -e cs_etm// taskset -c 0 make > > [ perf record: Captured and wrote 2.615 MB perf.data ] > > There are just 2.615 MB perf data rather than 2G, if you probe function > "tmc_alloc_etr_buf" in > > coresight_tmc module, you can find some clues: > > perf probe -m coresight_tmc "tmc_alloc_etr_buf size:s64" > > perf record -e probe:tmc_alloc_etr_buf -aR -- perf record -C 0 -m ,2G > -e cs_etm// -o cs.data taskset -c 0 make > > perf script > perf 118267 [064] 4640.324670: probe:tmc_alloc_etr_buf: > (ffff80007a9dce60) size_s64=-2147483648 > perf 118267 [064] 4640.324681: probe:tmc_alloc_etr_buf: > (ffff80007a9dce60) size_s64=1048576 > > It's pretty obvious what's going on here. The first call of > tmc_alloc_etr_buf in alloc_etr_buf was > > failed because of overflow, the second call of tmc_alloc_etr_buf just > alloc 1M AUX buffer which > > is default ETR buffer size rather than 2G. That is why we can just get > 2.615MB ( 1M AUX data > > + perf header ). > > It is necessary to check the conversion from int to s64 in coresight_tmc > driver. The issue[1] also > > exists in coresight/perf, but it's different from this topic. > Thanks for the investigation, that makes more sense to me now. Are you able to send a v2 of the patch with an updated commit message describing these symptoms instead? And you can also add: Reviewed-by: James Clark <james.clark@arm.com> > > [1]: > https://lore.kernel.org/bpf/20230711014120.53461-1-xueshuai@linux.alibaba.com/ > > Thanks > Ruidong > > On 2023/7/24 23:38, James Clark wrote: >> >> On 14/07/2023 09:43, Ruidong Tian wrote: >>> Perf cs_etm session will failed when AUX buffer > 1G. >>> >>> perf record -C 0 -m ,2G -e cs_etm// -- taskset -c 0 ls >>> failed to mmap with 12 (Cannot allocate memory) >>> >>> In coresight tmc driver, "nr_pages << PAGE_SHIFT" will overflow when >>> nr_pages >= 0x80000(correspond to 1G AUX buffer). Explicit convert >>> nr_pages >>> to 64 bit to avoid overflow. >>> >> Hi Ruidong, >> >> I couldn't reproduce this exact issue with the error message in the >> commit message. Is it not another manifestation related to this change >> [1]? I don't actually get any error message, but I was able to get a >> warning in dmesg even with [1] applied. >> >> Does the overflow not result in a successful session but with the wrong >> buffer size? >> >> I think the change makes sense, but maybe we also need a check for >> MAX_ORDER because I can trigger the same WARN_ON from [1]. Or maybe I'm >> a bit confused because of the other change and not being able to >> reproduce this exactly coming at the same time. >> >> [1]: >> https://lore.kernel.org/bpf/20230711014120.53461-1-xueshuai@linux.alibaba.com/ >> >> Thanks >> James >> >>> Signed-off-by: Ruidong Tian <tianruidong@linux.alibaba.com> >>> --- >>> drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 +- >>> drivers/hwtracing/coresight/coresight-tmc.h | 2 +- >>> 2 files changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c >>> b/drivers/hwtracing/coresight/coresight-tmc-etr.c >>> index 766325de0e29..1425ecd1cf78 100644 >>> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c >>> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c >>> @@ -1267,7 +1267,7 @@ alloc_etr_buf(struct tmc_drvdata *drvdata, >>> struct perf_event *event, >>> * than the size requested via sysfs. >>> */ >>> if ((nr_pages << PAGE_SHIFT) > drvdata->size) { >>> - etr_buf = tmc_alloc_etr_buf(drvdata, (nr_pages << PAGE_SHIFT), >>> + etr_buf = tmc_alloc_etr_buf(drvdata, ((ssize_t)nr_pages << >>> PAGE_SHIFT), >>> 0, node, NULL); >>> if (!IS_ERR(etr_buf)) >>> goto done; >>> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h >>> b/drivers/hwtracing/coresight/coresight-tmc.h >>> index b97da39652d2..0ee48c5ba764 100644 >>> --- a/drivers/hwtracing/coresight/coresight-tmc.h >>> +++ b/drivers/hwtracing/coresight/coresight-tmc.h >>> @@ -325,7 +325,7 @@ ssize_t tmc_sg_table_get_data(struct tmc_sg_table >>> *sg_table, >>> static inline unsigned long >>> tmc_sg_table_buf_size(struct tmc_sg_table *sg_table) >>> { >>> - return sg_table->data_pages.nr_pages << PAGE_SHIFT; >>> + return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT; >>> } >>> struct coresight_device *tmc_etr_get_catu_device(struct >>> tmc_drvdata *drvdata);
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index 766325de0e29..1425ecd1cf78 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -1267,7 +1267,7 @@ alloc_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event, * than the size requested via sysfs. */ if ((nr_pages << PAGE_SHIFT) > drvdata->size) { - etr_buf = tmc_alloc_etr_buf(drvdata, (nr_pages << PAGE_SHIFT), + etr_buf = tmc_alloc_etr_buf(drvdata, ((ssize_t)nr_pages << PAGE_SHIFT), 0, node, NULL); if (!IS_ERR(etr_buf)) goto done; diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h index b97da39652d2..0ee48c5ba764 100644 --- a/drivers/hwtracing/coresight/coresight-tmc.h +++ b/drivers/hwtracing/coresight/coresight-tmc.h @@ -325,7 +325,7 @@ ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table, static inline unsigned long tmc_sg_table_buf_size(struct tmc_sg_table *sg_table) { - return sg_table->data_pages.nr_pages << PAGE_SHIFT; + return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT; } struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
Perf cs_etm session will failed when AUX buffer > 1G. perf record -C 0 -m ,2G -e cs_etm// -- taskset -c 0 ls failed to mmap with 12 (Cannot allocate memory) In coresight tmc driver, "nr_pages << PAGE_SHIFT" will overflow when nr_pages >= 0x80000(correspond to 1G AUX buffer). Explicit convert nr_pages to 64 bit to avoid overflow. Signed-off-by: Ruidong Tian <tianruidong@linux.alibaba.com> --- drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 +- drivers/hwtracing/coresight/coresight-tmc.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)