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btrace, linux: use data_size and data_offset

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In struct perf_event_mmap_page there are new fields data_size and data_offset
that give the location of the perf_event data buffer relative to the mmap
page.  Use them if they are present.

gdb/
	* nat/linux-btrace.c (linux_enable_bts): Check for
	PERF_ATTR_SIZE_VER5.
	Check for data_offset and data_size fields.  Use them.
This commit is contained in:
Markus Metzger 2014-11-17 11:18:05 +01:00
parent b20a652466
commit 010a18a1b1
2 changed files with 22 additions and 5 deletions
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6
gdb/ChangeLog
View file

@ -1,3 +1,9 @@
2015-07-02 Markus Metzger <markus.t.metzger@intel.com>
* nat/linux-btrace.c (linux_enable_bts): Check for
PERF_ATTR_SIZE_VER5.
Check for data_offset and data_size fields. Use them.
2015-07-02 Markus Metzger <markus.t.metzger@intel.com>
* NEWS: Announce new commands "record btrace pt" and "record pt".

21
gdb/nat/linux-btrace.c
View file

@ -642,7 +642,7 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf)
struct perf_event_mmap_page *header;
struct btrace_target_info *tinfo;
struct btrace_tinfo_bts *bts;
unsigned long long size, pages;
unsigned long long size, pages, data_offset, data_size;
int pid, pg;
tinfo = xzalloc (sizeof (*tinfo));
@ -704,16 +704,27 @@ linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf)
break;
}
if (header == MAP_FAILED)
if (pages == 0)
goto err_file;
data_offset = PAGE_SIZE;
data_size = size;
#if defined (PERF_ATTR_SIZE_VER5)
if (offsetof (struct perf_event_mmap_page, data_size) <= header->size)
{
data_offset = header->data_offset;
data_size = header->data_size;
}
#endif /* defined (PERF_ATTR_SIZE_VER5) */
bts->header = header;
bts->bts.mem = ((const uint8_t *) header) + PAGE_SIZE;
bts->bts.size = size;
bts->bts.mem = ((const uint8_t *) header) + data_offset;
bts->bts.size = data_size;
bts->bts.data_head = &header->data_head;
bts->bts.last_head = 0;
tinfo->conf.bts.size = size;
tinfo->conf.bts.size = data_size;
return tinfo;
err_file: