DWARF register mappings have not been defined for some architectures,
at least for mips, so we can print an error message and then return
directly when use '--call-graph dwarf'.
E.g. without this patch:
[root@linux perf]# ./perf record --call-graph dwarf cd
Error:
The sys_perf_event_open() syscall returned with 89 (Function not implemented) for event (cycles).
/bin/dmesg | grep -i perf may provide additional information.
With this patch:
[root@linux perf]# ./perf record --call-graph dwarf cd
DWARF is not supported for architecture mips64
Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]
--call-graph <record_mode[,record_size]>
setup and enables call-graph (stack chain/backtrace):
record_mode: call graph recording mode (fp|dwarf|lbr)
record_size: if record_mode is 'dwarf', max size of stack recording (<bytes>)
default: 8192 (bytes)
Default: fp
Signed-off-by: Tiezhu Yang <[email protected]>
---
v2: Use HAVE_DWARF_SUPPORT to check
tools/perf/util/callchain.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 1b60985..ad08554 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -18,6 +18,7 @@
#include <math.h>
#include <linux/string.h>
#include <linux/zalloc.h>
+#include <sys/utsname.h>
#include "asm/bug.h"
@@ -276,6 +277,7 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
/* Dwarf style */
} else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
+#ifdef HAVE_DWARF_SUPPORT
const unsigned long default_stack_dump_size = 8192;
ret = 0;
@@ -290,6 +292,15 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
ret = get_stack_size(tok, &size);
param->dump_size = size;
}
+#else
+ struct utsname uts;
+
+ ret = uname(&uts);
+ pr_err("DWARF is not supported for architecture %s\n",
+ ret ? "unknown" : uts.machine);
+
+ return -ENOTSUP;
+#endif
} else if (!strncmp(name, "lbr", sizeof("lbr"))) {
if (!strtok_r(NULL, ",", &saveptr)) {
param->record_mode = CALLCHAIN_LBR;
--
2.1.0
Em Tue, Dec 15, 2020 at 09:35:31AM +0800, Tiezhu Yang escreveu:
> DWARF register mappings have not been defined for some architectures,
> at least for mips, so we can print an error message and then return
> directly when use '--call-graph dwarf'.
>
> E.g. without this patch:
Thanks, applied.
- Arnaldo
Hello,
On Tue, Dec 15, 2020 at 10:35 AM Tiezhu Yang <[email protected]> wrote:
>
> DWARF register mappings have not been defined for some architectures,
> at least for mips, so we can print an error message and then return
> directly when use '--call-graph dwarf'.
>
> E.g. without this patch:
>
> [root@linux perf]# ./perf record --call-graph dwarf cd
> Error:
> The sys_perf_event_open() syscall returned with 89 (Function not implemented) for event (cycles).
> /bin/dmesg | grep -i perf may provide additional information.
>
> With this patch:
>
> [root@linux perf]# ./perf record --call-graph dwarf cd
> DWARF is not supported for architecture mips64
>
> Usage: perf record [<options>] [<command>]
> or: perf record [<options>] -- <command> [<options>]
>
> --call-graph <record_mode[,record_size]>
> setup and enables call-graph (stack chain/backtrace):
>
> record_mode: call graph recording mode (fp|dwarf|lbr)
> record_size: if record_mode is 'dwarf', max size of stack recording (<bytes>)
> default: 8192 (bytes)
>
> Default: fp
>
> Signed-off-by: Tiezhu Yang <[email protected]>
> ---
>
> v2: Use HAVE_DWARF_SUPPORT to check
I'm not sure whether this is because of lack of dwarf library or kernel support.
Based on the error message, I guess it's from the kernel. Then I think this
patch won't be sufficient..
Thanks,
Namhyung
>
> tools/perf/util/callchain.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index 1b60985..ad08554 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -18,6 +18,7 @@
> #include <math.h>
> #include <linux/string.h>
> #include <linux/zalloc.h>
> +#include <sys/utsname.h>
>
> #include "asm/bug.h"
>
> @@ -276,6 +277,7 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
>
> /* Dwarf style */
> } else if (!strncmp(name, "dwarf", sizeof("dwarf"))) {
> +#ifdef HAVE_DWARF_SUPPORT
> const unsigned long default_stack_dump_size = 8192;
>
> ret = 0;
> @@ -290,6 +292,15 @@ int parse_callchain_record(const char *arg, struct callchain_param *param)
> ret = get_stack_size(tok, &size);
> param->dump_size = size;
> }
> +#else
> + struct utsname uts;
> +
> + ret = uname(&uts);
> + pr_err("DWARF is not supported for architecture %s\n",
> + ret ? "unknown" : uts.machine);
> +
> + return -ENOTSUP;
> +#endif
> } else if (!strncmp(name, "lbr", sizeof("lbr"))) {
> if (!strtok_r(NULL, ",", &saveptr)) {
> param->record_mode = CALLCHAIN_LBR;
> --
> 2.1.0
>
Em Tue, Dec 15, 2020 at 10:49:59PM +0900, Namhyung Kim escreveu:
> Hello,
>
> On Tue, Dec 15, 2020 at 10:35 AM Tiezhu Yang <[email protected]> wrote:
> >
> > DWARF register mappings have not been defined for some architectures,
> > at least for mips, so we can print an error message and then return
> > directly when use '--call-graph dwarf'.
> >
> > E.g. without this patch:
> >
> > [root@linux perf]# ./perf record --call-graph dwarf cd
> > Error:
> > The sys_perf_event_open() syscall returned with 89 (Function not implemented) for event (cycles).
> > /bin/dmesg | grep -i perf may provide additional information.
> >
> > With this patch:
> >
> > [root@linux perf]# ./perf record --call-graph dwarf cd
> > DWARF is not supported for architecture mips64
> >
> > Usage: perf record [<options>] [<command>]
> > or: perf record [<options>] -- <command> [<options>]
> >
> > --call-graph <record_mode[,record_size]>
> > setup and enables call-graph (stack chain/backtrace):
> >
> > record_mode: call graph recording mode (fp|dwarf|lbr)
> > record_size: if record_mode is 'dwarf', max size of stack recording (<bytes>)
> > default: 8192 (bytes)
> >
> > Default: fp
> >
> > Signed-off-by: Tiezhu Yang <[email protected]>
> > ---
> >
> > v2: Use HAVE_DWARF_SUPPORT to check
>
> I'm not sure whether this is because of lack of dwarf library or kernel support.
> Based on the error message, I guess it's from the kernel. Then I think this
> patch won't be sufficient..
tools/perf/Makefile.config
ifndef NO_DWARF
ifeq ($(origin PERF_HAVE_DWARF_REGS), undefined)
msg := $(warning DWARF register mappings have not been defined for architecture $(SRCARCH), DWARF support disabled);
NO_DWARF := 1
else
CFLAGS += -DHAVE_DWARF_SUPPORT $(LIBDW_CFLAGS)
LDFLAGS += $(LIBDW_LDFLAGS)
EXTLIBS += ${DWARFLIBS}
$(call detected,CONFIG_DWARF)
endif # PERF_HAVE_DWARF_REGS
endif # NO_DWARF
[acme@five perf]$ find tools/perf -type f | xargs grep PERF_HAVE_DWARF_REGS
tools/perf/arch/xtensa/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/x86/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/arm64/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/arm/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/s390/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/powerpc/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/sh/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/riscv/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/sparc/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/arch/csky/Makefile:PERF_HAVE_DWARF_REGS := 1
tools/perf/Makefile.config: ifeq ($(origin PERF_HAVE_DWARF_REGS), undefined)
tools/perf/Makefile.config: endif # PERF_HAVE_DWARF_REGS
[acme@five perf]$
Ouch:
[acme@five perf]$ cat tools/perf/arch/xtensa/Makefile
# SPDX-License-Identifier: GPL-2.0-only
ifndef NO_DWARF
PERF_HAVE_DWARF_REGS := 1
endif
[acme@five perf]$
So you have a point, only if NO_DWARF is not defined, then
PERF_HAVE_DWARF_REGS is can be used to define HAVE_DWARF_SUPPORT, too
clumsy.
So probably my hunch that this should be done at
evsel__open_strerror() and use perf_missing_features.dwarf_regs is
what we should go...
I'm removing this patch from my current tree, please take a look at:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/commit/?h=tmp.perf/core&id=f55c66234c1967f6e56e56c3e084f80b417c124b
For how I did this for another feature that the kernel may or not
support, perf_event_open() fails, it notices that in
perf_missing_features and then later evsel__open_strerror() returns a
sensible warning, reacting to something the running kernel returned.
- Arnaldo