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Date: Wed, 24 Jul 2019 14:27:03 +0200
From: Thomas Richter <tmricht@...ux.ibm.com>
To: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
acme@...nel.org
Cc: brueckner@...ux.ibm.com, gor@...ux.ibm.com,
heiko.carstens@...ibm.com, Thomas Richter <tmricht@...ux.ibm.com>,
stable@...r.kernel.org
Subject: [PATCH 2/2] perf/top: Fix s390 gap between kernel end and module start
During execution of command 'perf top' the error message:
Not enough memory for annotating '__irf_end' symbol!)
is emitted from this call sequence:
__cmd_top
perf_top__mmap_read
perf_top__mmap_read_idx
perf_event__process_sample
hist_entry_iter__add
hist_iter__top_callback
perf_top__record_precise_ip
hist_entry__inc_addr_samples
symbol__inc_addr_samples
symbol__get_annotation
symbol__alloc_hist
In this function the size of symbol __irf_end is calculated. The size
of a symbol is the difference between its start and end address.
When the symbol was read the first time, its start and end was set to:
symbol__new: __irf_end 0xe954d0-0xe954d0
which is correct and maps with /proc/kallsyms:
root@...60046:~/linux-4.15.0/tools/perf# fgrep _irf_end /proc/kallsyms
0000000000e954d0 t __irf_end
root@...60046:~/linux-4.15.0/tools/perf#
In function symbol__alloc_hist() the end of symbol __irf_end is
symbol__alloc_hist sym:__irf_end start:0xe954d0 end:0x3ff80045a8
which is identical with the first module entry in /proc/kallsyms
This results in a symbol size of __irf_req for histogram analyses of
70334140059072 bytes and a malloc() for this requested size fails.
The root cause of this is function
__dso__load_kallsyms()
+-> symbols__fixup_end()
Function symbols__fixup_end() enlarges the last symbol in the
kallsyms map
# fgrep __irf_end /proc/kallsyms
0000000000e954d0 t __irf_end
#
to the start address of the first module:
# cat /proc/kallsyms | sort | egrep ' [tT] '
....
0000000000e952d0 T __security_initcall_end
0000000000e954d0 T __initramfs_size
0000000000e954d0 t __irf_end
000003ff800045a8 T fc_get_event_number [scsi_transport_fc]
000003ff800045d0 t store_fc_vport_disable [scsi_transport_fc]
000003ff800046a8 T scsi_is_fc_rport [scsi_transport_fc]
000003ff800046d0 t fc_target_setup [scsi_transport_fc]
On s390 the kernel is located around memory address 0x200, 0x10000
or 0x100000, depending on linux version. Modules however start some-
where around 0x3ff xxxx xxxx.
This is different than x86 and produces a large gap for which
histogram allocation fails.
Fix this by detecting the kernel's last symbol and do no
adjustment for it. Introduce a weak function and handle s390 specifics.
Cc: <stable@...r.kernel.org>
Reported-by: Klaus Theurich <klaus.theurich@...ibm.com>
Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@...ibm.com>
---
tools/perf/arch/s390/util/machine.c | 17 +++++++++++++++++
tools/perf/util/symbol.c | 7 ++++++-
tools/perf/util/symbol.h | 1 +
3 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/tools/perf/arch/s390/util/machine.c b/tools/perf/arch/s390/util/machine.c
index de26b1441a48..c8c86a0c9b79 100644
--- a/tools/perf/arch/s390/util/machine.c
+++ b/tools/perf/arch/s390/util/machine.c
@@ -6,6 +6,7 @@
#include "machine.h"
#include "api/fs/fs.h"
#include "debug.h"
+#include "symbol.h"
int arch__fix_module_text_start(u64 *start, u64 *size, const char *name)
{
@@ -33,3 +34,19 @@ int arch__fix_module_text_start(u64 *start, u64 *size, const char *name)
return 0;
}
+
+/* On s390 kernel text segment start is located at very low memory addresses,
+ * for example 0x10000. Modules are located at very high memory addresses,
+ * for example 0x3ff xxxx xxxx. The gap between end of kernel text segment
+ * and beginning of first module's text segment is very big.
+ * Therefore do not fill this gap and do not assign it to the kernel dso map.
+ */
+void arch__symbols__fixup_end(struct symbol *p, struct symbol *c)
+{
+ if (strchr(p->name, '[') == NULL && strchr(c->name, '['))
+ /* Last kernel symbol mapped to end of page */
+ p->end = roundup(p->end, page_size);
+ else
+ p->end = c->start;
+ pr_debug4("%s sym:%s end:%#lx\n", __func__, p->name, p->end);
+}
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 5cbad55cd99d..3b49eb4e3ed9 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -91,6 +91,11 @@ static int prefix_underscores_count(const char *str)
return tail - str;
}
+void __weak arch__symbols__fixup_end(struct symbol *p, struct symbol *c)
+{
+ p->end = c->start;
+}
+
const char * __weak arch__normalize_symbol_name(const char *name)
{
return name;
@@ -217,7 +222,7 @@ void symbols__fixup_end(struct rb_root_cached *symbols)
curr = rb_entry(nd, struct symbol, rb_node);
if (prev->end == prev->start && prev->end != curr->start)
- prev->end = curr->start;
+ arch__symbols__fixup_end(prev, curr);
}
/* Last entry */
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 9a8fe012910a..f30ab608ea54 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -277,6 +277,7 @@ const char *arch__normalize_symbol_name(const char *name);
#define SYMBOL_A 0
#define SYMBOL_B 1
+void arch__symbols__fixup_end(struct symbol *p, struct symbol *c);
int arch__compare_symbol_names(const char *namea, const char *nameb);
int arch__compare_symbol_names_n(const char *namea, const char *nameb,
unsigned int n);
--
2.21.0
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