Re: [PATCH v2 16/31] perf dwarf-regs: Pass accurate disassembly machine to get_dwarf_regnum

[Google]

On Sat,  5 Oct 2024 12:55:26 -0700
Ian Rogers <irogers@xxxxxxxxxx> wrote:

> Rather than pass 0/EM_NONE, use the value computed in the disasm
> struct arch. Switch the EM_NONE case to EM_HOST, rewriting EM_NONE if
> it were passed to get_dwarf_regnum. Pass a flags value as
> architectures like csky need the flags to determine the ABI variant.
> 

Does this change the command output when we use it for cross-build
environment? E.g. remote arch is different from host arch? If so,
please add output examples with/without this change.

Thank you,

> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> ---
>  tools/perf/util/annotate.c           | 6 +++---
>  tools/perf/util/dwarf-regs.c         | 8 ++++++--
>  tools/perf/util/include/dwarf-regs.h | 5 +++--
>  3 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
> index 37ce43c4eb8f..b1d98da79be8 100644
> --- a/tools/perf/util/annotate.c
> +++ b/tools/perf/util/annotate.c
> @@ -2292,7 +2292,7 @@ static int extract_reg_offset(struct arch *arch, const char *str,
>  	if (regname == NULL)
>  		return -1;
>  
> -	op_loc->reg1 = get_dwarf_regnum(regname, 0);
> +	op_loc->reg1 = get_dwarf_regnum(regname, arch->e_machine, arch->e_flags);
>  	free(regname);
>  
>  	/* Get the second register */
> @@ -2305,7 +2305,7 @@ static int extract_reg_offset(struct arch *arch, const char *str,
>  		if (regname == NULL)
>  			return -1;
>  
> -		op_loc->reg2 = get_dwarf_regnum(regname, 0);
> +		op_loc->reg2 = get_dwarf_regnum(regname, arch->e_machine, arch->e_flags);
>  		free(regname);
>  	}
>  	return 0;
> @@ -2405,7 +2405,7 @@ int annotate_get_insn_location(struct arch *arch, struct disasm_line *dl,
>  				return -1;
>  
>  			if (*s == arch->objdump.register_char)
> -				op_loc->reg1 = get_dwarf_regnum(s, 0);
> +				op_loc->reg1 = get_dwarf_regnum(s, arch->e_machine, arch->e_flags);
>  			else if (*s == arch->objdump.imm_char) {
>  				op_loc->offset = strtol(s + 1, &p, 0);
>  				if (p && p != s + 1)
> diff --git a/tools/perf/util/dwarf-regs.c b/tools/perf/util/dwarf-regs.c
> index 7c01bc4d7e5b..1321387f6948 100644
> --- a/tools/perf/util/dwarf-regs.c
> +++ b/tools/perf/util/dwarf-regs.c
> @@ -70,7 +70,7 @@ __weak int get_arch_regnum(const char *name __maybe_unused)
>  }
>  
>  /* Return DWARF register number from architecture register name */
> -int get_dwarf_regnum(const char *name, unsigned int machine)
> +int get_dwarf_regnum(const char *name, unsigned int machine, unsigned int flags __maybe_unused)
>  {
>  	char *regname = strdup(name);
>  	int reg = -1;
> @@ -84,8 +84,12 @@ int get_dwarf_regnum(const char *name, unsigned int machine)
>  	if (p)
>  		*p = '\0';
>  
> +	if (machine == EM_NONE) {
> +		/* Generic arch - use host arch */
> +		machine = EM_HOST;
> +	}
>  	switch (machine) {
> -	case EM_NONE:	/* Generic arch - use host arch */
> +	case EM_HOST:
>  		reg = get_arch_regnum(regname);
>  		break;
>  	default:
> diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
> index f4f87ded5e3d..ee0a734564c7 100644
> --- a/tools/perf/util/include/dwarf-regs.h
> +++ b/tools/perf/util/include/dwarf-regs.h
> @@ -93,12 +93,13 @@ int get_arch_regnum(const char *name);
>   * name: architecture register name
>   * machine: ELF machine signature (EM_*)
>   */
> -int get_dwarf_regnum(const char *name, unsigned int machine);
> +int get_dwarf_regnum(const char *name, unsigned int machine, unsigned int flags);
>  
>  #else /* HAVE_LIBDW_SUPPORT */
>  
>  static inline int get_dwarf_regnum(const char *name __maybe_unused,
> -				   unsigned int machine __maybe_unused)
> +				   unsigned int machine __maybe_unused,
> +				   unsigned int flags __maybe_unused)
>  {
>  	return -1;
>  }
> -- 
> 2.47.0.rc0.187.ge670bccf7e-goog
> 


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>