On s390 the modules loaded in memory have the text segment located after the GOT and Relocation table. This can be seen with this output: [root@m35lp76 perf]# fgrep qeth /proc/modules qeth 151552 1 qeth_l2, Live 0x000003ff800b2000 ... [root@m35lp76 perf]# cat /sys/module/qeth/sections/.text 0x000003ff800b3990 [root@m35lp76 perf]#
There is an offset of 0x1990 bytes. The size of the qeth module is 151552 bytes (0x25000 in hex). The location of the GOT/relocation table at the beginning of a module is unique to s390.
commit 203d8a4aa6ed ("perf s390: Fix 'start' address of module's map") adjusts the start address of a module in the map structures, but does not adjust the size of the modules. This leads to overlapping of module maps as this example shows:
[root@m35lp76 perf] # ./perf report -D 0 0 0xfb0 [0xa0]: PERF_RECORD_MMAP -1/0: [0x3ff800b3990(0x25000) @ 0]: x /lib/modules/.../qeth.ko.xz 0 0 0x1050 [0xb0]: PERF_RECORD_MMAP -1/0: [0x3ff800d85a0(0x8000) @ 0]: x /lib/modules/.../ip6_tables.ko.xz
The module qeth.ko has an adjusted start address modified to b3990, but its size is unchanged and the module ends at 0x3ff800d8990. This end address overlaps with the next modules start address of 0x3ff800d85a0.
When the size of the leading GOT/Relocation table stored in the beginning of the text segment (0x1990 bytes) is subtracted from module qeth end address, there are no overlaps anymore:
0x3ff800d8990 - 0x1990 = 0x0x3ff800d7000
which is the same as
0x3ff800b2000 + 0x25000 = 0x0x3ff800d7000.
To fix this issue, also adjust the modules size in function arch__fix_module_text_start(). Add another function parameter named size and reduce the size of the module when the text segment start address is changed.
Output after: 0 0 0xfb0 [0xa0]: PERF_RECORD_MMAP -1/0: [0x3ff800b3990(0x23670) @ 0]: x /lib/modules/.../qeth.ko.xz 0 0 0x1050 [0xb0]: PERF_RECORD_MMAP -1/0: [0x3ff800d85a0(0x7a60) @ 0]: x /lib/modules/.../ip6_tables.ko.xz
Fixes: 203d8a4aa6ed ("perf s390: Fix 'start' address of module's map") Cc: stable@vger.kernel.org # v4.9+ Reported-by: Stefan Liebler stli@linux.ibm.com Signed-off-by: Thomas Richter tmricht@linux.ibm.com Acked-by: Heiko Carstens heiko.carstens@de.ibm.com --- tools/perf/arch/s390/util/machine.c | 14 +++++++++++++- tools/perf/util/machine.c | 3 ++- tools/perf/util/machine.h | 2 +- 3 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/tools/perf/arch/s390/util/machine.c b/tools/perf/arch/s390/util/machine.c index a19690a17291..de26b1441a48 100644 --- a/tools/perf/arch/s390/util/machine.c +++ b/tools/perf/arch/s390/util/machine.c @@ -7,7 +7,7 @@ #include "api/fs/fs.h" #include "debug.h"
-int arch__fix_module_text_start(u64 *start, const char *name) +int arch__fix_module_text_start(u64 *start, u64 *size, const char *name) { u64 m_start = *start; char path[PATH_MAX]; @@ -17,6 +17,18 @@ int arch__fix_module_text_start(u64 *start, const char *name) if (sysfs__read_ull(path, (unsigned long long *)start) < 0) { pr_debug2("Using module %s start:%#lx\n", path, m_start); *start = m_start; + } else { + /* Successful read of the modules segment text start address. + * Calculate difference between module start address + * in memory and module text segment start address. + * For example module load address is 0x3ff8011b000 + * (from /proc/modules) and module text segment start + * address is 0x3ff8011b870 (from file above). + * + * Adjust the module size and subtract the GOT table + * size located at the beginning of the module. + */ + *size -= (*start - m_start); }
return 0; diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index dc7aafe45a2b..081fe4bdebaa 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -1365,6 +1365,7 @@ static int machine__set_modules_path(struct machine *machine) return map_groups__set_modules_path_dir(&machine->kmaps, modules_path, 0); } int __weak arch__fix_module_text_start(u64 *start __maybe_unused, + u64 *size __maybe_unused, const char *name __maybe_unused) { return 0; @@ -1376,7 +1377,7 @@ static int machine__create_module(void *arg, const char *name, u64 start, struct machine *machine = arg; struct map *map;
- if (arch__fix_module_text_start(&start, name) < 0) + if (arch__fix_module_text_start(&start, &size, name) < 0) return -1;
map = machine__findnew_module_map(machine, start, name); diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h index f70ab98a7bde..7aa38da26427 100644 --- a/tools/perf/util/machine.h +++ b/tools/perf/util/machine.h @@ -222,7 +222,7 @@ struct symbol *machine__find_kernel_symbol_by_name(struct machine *machine,
struct map *machine__findnew_module_map(struct machine *machine, u64 start, const char *filename); -int arch__fix_module_text_start(u64 *start, const char *name); +int arch__fix_module_text_start(u64 *start, u64 *size, const char *name);
int machine__load_kallsyms(struct machine *machine, const char *filename);
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@s8360046:~/linux-4.15.0/tools/perf# fgrep _irf_end /proc/kallsyms 0000000000e954d0 t __irf_end root@s8360046:~/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@vger.kernel.org Reported-by: Klaus Theurich klaus.theurich@de.ibm.com Signed-off-by: Thomas Richter tmricht@linux.ibm.com Acked-by: Heiko Carstens heiko.carstens@de.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);
linux-stable-mirror@lists.linaro.org
-
Arnaldo Carvalho de Melo -
Thomas Richter