From b9c0a64901d5bdec6eafd38d1dc8fa0e2974fccb Mon Sep 17 00:00:00 2001 From: Thomas Richter Date: Wed, 24 Jul 2019 14:27:03 +0200 Subject: perf annotate: 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@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 Signed-off-by: Thomas Richter Acked-by: Heiko Carstens Cc: Hendrik Brueckner Cc: Vasily Gorbik 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 --- tools/perf/arch/s390/util/machine.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'tools/perf/arch') 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); +} -- cgit v1.2.3-59-g8ed1b