From: Thomas Richter tmricht@linux.ibm.com

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.

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 Cc: Hendrik Brueckner brueckner@linux.ibm.com Cc: Vasily Gorbik gor@linux.ibm.com Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20190724122703.3996-2-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.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 173f3378aaa0..4efde7879474 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -92,6 +92,11 @@ 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; @@ -218,7 +223,7 @@ 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 12755b42ea93..183f630cb5f1 100644 --- a/tools/perf/util/symbol.h +++ b/tools/perf/util/symbol.h @@ -288,6 +288,7 @@ 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);