Re: [PATCH] perf tools: Support bpf prologue for arm64

[He Kuang <hekuang@huawei.com>]

Hi, Arnaldo

On 2015/9/1 4:16, Arnaldo Carvalho de Melo wrote:
> Em Sat, Aug 29, 2015 at 03:16:52AM +0000, He Kuang escreveu:
>> This patch implements arch_get_reg_info() for arm64 to enable
>> HAVE_BPF_PROLOGUE feature. For arm64, structure pt_regs is not composed
>> by fields of register names but an array of regs, so here we simply
>> multiply fixed register size by index number to get the byte offset.
>
> Hi Jean, Will, are you ok with this? Can I have Acked-by or Reviewed-by
> tags from you?
>
> He, please try to add the authors of the files you change in the CC
> list.

Ok, usually I use the get_maintainers.pl script, but it seems that the
output do not include file authors:

./scripts/get_maintainer.pl 0001-perf-tools-Support-bpf-prologue-for-arm64.patch
Peter Zijlstra <a.p.zijlstra@chello.nl> (supporter:PERFORMANCE EVENTS SUBSYSTEM)
Ingo Molnar <mingo@redhat.com> (supporter:PERFORMANCE EVENTS SUBSYSTEM)
Arnaldo Carvalho de Melo <acme@kernel.org> (supporter:PERFORMANCE EVENTS SUBSYSTEM,commit_signer:1/2=50%)
Jiri Olsa <jolsa@kernel.org> (commit_signer:1/2=50%,authored:1/2=50%,removed_lines:4/4=100%)
He Kuang <hekuang@huawei.com> (commit_signer:1/2=50%,authored:1/2=50%,added_lines:1/1=100%,commit_signer:1/1=100%,authored:1/1=100%,added_lines:23/23=100%)
linux-kernel@vger.kernel.org (open list:PERFORMANCE EVENTS SUBSYSTEM)

get_maintainers.pl bug?

>
> - Arnaldo
>
>> Signed-off-by: He Kuang <hekuang@huawei.com>
>> ---
>>   tools/perf/arch/arm64/Makefile          |  1 +
>>   tools/perf/arch/arm64/util/dwarf-regs.c | 26 ++++++++++++++++++++++++++
>>   2 files changed, 27 insertions(+)
>>
>> diff --git a/tools/perf/arch/arm64/Makefile b/tools/perf/arch/arm64/Makefile
>> index 7fbca17..1256e6e 100644
>> --- a/tools/perf/arch/arm64/Makefile
>> +++ b/tools/perf/arch/arm64/Makefile
>> @@ -1,3 +1,4 @@
>>   ifndef NO_DWARF
>>   PERF_HAVE_DWARF_REGS := 1
>>   endif
>> +PERF_HAVE_ARCH_GET_REG_INFO := 1
>> diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c
>> index d49efeb..cb2c50a 100644
>> --- a/tools/perf/arch/arm64/util/dwarf-regs.c
>> +++ b/tools/perf/arch/arm64/util/dwarf-regs.c
>> @@ -10,6 +10,10 @@
>>
>>   #include <stddef.h>
>>   #include <dwarf-regs.h>
>> +#include <string.h>
>> +#include <linux/ptrace.h>
>> +
>> +#define PT_REG_SIZE (sizeof(((struct user_pt_regs *)0)->regs[0]))
>>
>>   struct pt_regs_dwarfnum {
>>   	const char *name;
>> @@ -78,3 +82,25 @@ const char *get_arch_regstr(unsigned int n)
>>   			return roff->name;
>>   	return NULL;
>>   }
>> +
>> +#ifdef HAVE_BPF_PROLOGUE
>> +int arch_get_reg_info(const char *name, int *offset)
>> +{
>> +	const struct pt_regs_dwarfnum *roff;
>> +
>> +	if (!name || !offset)
>> +		return -1;
>> +
>> +	for (roff = regdwarfnum_table; roff->name != NULL; roff++) {
>> +		if (!strcmp(roff->name, name)) {
>> +			if (roff->dwarfnum < 0)
>> +				return -1;

Here's a compile error.
error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]

So remove this useless comparison:
---
  tools/perf/arch/arm64/Makefile          |  1 +
  tools/perf/arch/arm64/util/dwarf-regs.c | 23 +++++++++++++++++++++++
  2 files changed, 24 insertions(+)

diff --git a/tools/perf/arch/arm64/Makefile b/tools/perf/arch/arm64/Makefile
index 7fbca17..1256e6e 100644
--- a/tools/perf/arch/arm64/Makefile
+++ b/tools/perf/arch/arm64/Makefile
@@ -1,3 +1,4 @@
  ifndef NO_DWARF
  PERF_HAVE_DWARF_REGS := 1
  endif
+PERF_HAVE_ARCH_GET_REG_INFO := 1
diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c
index d49efeb..cb935c4 100644
--- a/tools/perf/arch/arm64/util/dwarf-regs.c
+++ b/tools/perf/arch/arm64/util/dwarf-regs.c
@@ -10,6 +10,10 @@
  
  #include <stddef.h>
  #include <dwarf-regs.h>
+#include <string.h>
+#include <linux/ptrace.h>
+
+#define PT_REG_SIZE (sizeof(((struct user_pt_regs *)0)->regs[0]))
  
  struct pt_regs_dwarfnum {
  	const char *name;
@@ -78,3 +82,22 @@ const char *get_arch_regstr(unsigned int n)
  			return roff->name;
  	return NULL;
  }
+
+#ifdef HAVE_BPF_PROLOGUE
+int arch_get_reg_info(const char *name, int *offset)
+{
+	const struct pt_regs_dwarfnum *roff;
+
+	if (!name || !offset)
+		return -1;
+
+	for (roff = regdwarfnum_table; roff->name != NULL; roff++) {
+		if (!strcmp(roff->name, name)) {
+			*offset = roff->dwarfnum * PT_REG_SIZE;
+			return 0;
+		}
+	}
+
+	return -1;
+}
+#endif
-- 
1.8.5.2