Re: [PATCH v2 18/31] perf dwarf-regs: Move x86 dwarf-regs out of arch

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Sat,  5 Oct 2024 12:55:28 -0700
Ian Rogers <irogers@google.com> wrote:

> Move arch/x86/util/dwarf-regs.c to util/dwarf-regs-x86.c and compile
> in unconditionally. To avoid get_arch_regnum being duplicated, rename
> to get_x86_regnum and add to get_dwarf_regnum switch.
> 
> For get_arch_regstr, this was unused on x86 unless the machine type
> was EM_NONE. Map that case to EM_HOST and remove get_arch_regstr from
> dwarf-regs-x86.c.
> 

Hmm, I'm not sure this change. I feel like to keep the arch dependent
part under arch/ directory. But if this is just for reverse mapping of
regname -> regnum, since we already have regnum -> regname maps in the
header file, we can reimplement get_dwarf_regnum() as a generic function.
And that is what you does in this series, correct?

If so, can you make a generic get_dwarf_regnum() at first, and remove
the architecture dependent part which is not needed anymore.
That should be more simpler to review.

Thank you,
 

> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/arch/x86/util/Build                |  3 ---
>  tools/perf/util/Build                         |  1 +
>  .../dwarf-regs.c => util/dwarf-regs-x86.c}    | 24 +------------------
>  tools/perf/util/dwarf-regs.c                  | 17 +++++++++++++
>  tools/perf/util/include/dwarf-regs.h          |  8 +++++++
>  5 files changed, 27 insertions(+), 26 deletions(-)
>  rename tools/perf/{arch/x86/util/dwarf-regs.c => util/dwarf-regs-x86.c} (77%)
> 
> diff --git a/tools/perf/arch/x86/util/Build b/tools/perf/arch/x86/util/Build
> index 9705cda4f240..70af491a6dd7 100644
> --- a/tools/perf/arch/x86/util/Build
> +++ b/tools/perf/arch/x86/util/Build
> @@ -12,9 +12,6 @@ perf-util-y += evsel.o
>  perf-util-y += iostat.o
>  perf-util-y += env.o
>  
> -perf-util-$(CONFIG_LIBDW) += dwarf-regs.o
> -perf-util-$(CONFIG_BPF_PROLOGUE) += dwarf-regs.o
> -
>  perf-util-$(CONFIG_LOCAL_LIBUNWIND)    += unwind-libunwind.o
>  perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
>  
> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index 1d08608b7e1b..c2221ef431f3 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -202,6 +202,7 @@ endif
>  perf-util-$(CONFIG_LIBDW) += probe-finder.o
>  perf-util-$(CONFIG_LIBDW) += dwarf-aux.o
>  perf-util-$(CONFIG_LIBDW) += dwarf-regs.o
> +perf-util-$(CONFIG_LIBDW) += dwarf-regs-x86.o
>  perf-util-$(CONFIG_LIBDW) += debuginfo.o
>  perf-util-$(CONFIG_LIBDW) += annotate-data.o
>  
> diff --git a/tools/perf/arch/x86/util/dwarf-regs.c b/tools/perf/util/dwarf-regs-x86.c
> similarity index 77%
> rename from tools/perf/arch/x86/util/dwarf-regs.c
> rename to tools/perf/util/dwarf-regs-x86.c
> index 530905118cd4..7a55c65e8da6 100644
> --- a/tools/perf/arch/x86/util/dwarf-regs.c
> +++ b/tools/perf/util/dwarf-regs-x86.c
> @@ -11,28 +11,6 @@
>  #include <linux/kernel.h> /* for ARRAY_SIZE */
>  #include <dwarf-regs.h>
>  
> -#define DEFINE_DWARF_REGSTR_TABLE 1
> -#include "dwarf-regs-table.h"
> -
> -/* Return architecture dependent register string (for kprobe-tracer) */
> -const char *get_arch_regstr(unsigned int n)
> -{
> -#if defined(__i386__)
> -	size_t len = ARRAY_SIZE(x86_32_regstr_tbl);
> -#else
> -	size_t len = ARRAY_SIZE(x86_64_regstr_tbl);
> -#endif
> -
> -	if (n >= len)
> -		return NULL;
> -
> -#if defined(__i386__)
> -	return x86_32_regstr_tbl[n];
> -#else
> -	return x86_64_regstr_tbl[n];
> -#endif
> -}
> -
>  struct dwarf_regs_idx {
>  	const char *name;
>  	int idx;
> @@ -58,7 +36,7 @@ static const struct dwarf_regs_idx x86_regidx_table[] = {
>  	{ "rip", DWARF_REG_PC },
>  };
>  
> -int get_arch_regnum(const char *name)
> +int get_x86_regnum(const char *name)
>  {
>  	unsigned int i;
>  
> diff --git a/tools/perf/util/dwarf-regs.c b/tools/perf/util/dwarf-regs.c
> index 86b3ef638fbb..eac99a246737 100644
> --- a/tools/perf/util/dwarf-regs.c
> +++ b/tools/perf/util/dwarf-regs.c
> @@ -32,9 +32,17 @@
>  const char *get_dwarf_regstr(unsigned int n, unsigned int machine,
>  			     unsigned int flags __maybe_unused)
>  {
> +#if EM_HOST == EM_X86_64 || EM_HOST == EM_386
> +	if (machine == EM_NONE) {
> +		/* Generic arch - use host arch */
> +		machine = EM_HOST;
> +	}
> +#endif
>  	switch (machine) {
> +#if EM_HOST != EM_X86_64 && EM_HOST != EM_386
>  	case EM_NONE:	/* Generic arch - use host arch */
>  		return get_arch_regstr(n);
> +#endif
>  	case EM_386:
>  		return __get_dwarf_regstr(x86_32_regstr_tbl, n);
>  	case EM_X86_64:
> @@ -65,10 +73,12 @@ const char *get_dwarf_regstr(unsigned int n, unsigned int machine,
>  	return NULL;
>  }
>  
> +#if EM_HOST != EM_X86_64 && EM_HOST != EM_386
>  __weak int get_arch_regnum(const char *name __maybe_unused)
>  {
>  	return -ENOTSUP;
>  }
> +#endif
>  
>  /* Return DWARF register number from architecture register name */
>  int get_dwarf_regnum(const char *name, unsigned int machine, unsigned int flags __maybe_unused)
> @@ -90,9 +100,16 @@ int get_dwarf_regnum(const char *name, unsigned int machine, unsigned int flags
>  		machine = EM_HOST;
>  	}
>  	switch (machine) {
> +#if EM_HOST != EM_X86_64 && EM_HOST != EM_386
>  	case EM_HOST:
>  		reg = get_arch_regnum(regname);
>  		break;
> +#endif
> +	case EM_X86_64:
> +		fallthrough;
> +	case EM_386:
> +		reg = get_x86_regnum(regname);
> +		break;
>  	default:
>  		pr_err("ELF MACHINE %x is not supported.\n", machine);
>  	}
> diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
> index 925525405e2d..062623aefd5a 100644
> --- a/tools/perf/util/include/dwarf-regs.h
> +++ b/tools/perf/util/include/dwarf-regs.h
> @@ -79,7 +79,10 @@
>  #define DWARF_REG_FB  0xd3affb /* random number */
>  
>  #ifdef HAVE_LIBDW_SUPPORT
> +#if !defined(__x86_64__) && !defined(__i386__)
>  const char *get_arch_regstr(unsigned int n);
> +#endif
> +
>  /**
>   * get_dwarf_regstr() - Returns ftrace register string from DWARF regnum.
>   * @n: DWARF register number.
> @@ -88,7 +91,12 @@ const char *get_arch_regstr(unsigned int n);
>   */
>  const char *get_dwarf_regstr(unsigned int n, unsigned int machine, unsigned int flags);
>  
> +int get_x86_regnum(const char *name);
> +
> +#if !defined(__x86_64__) && !defined(__i386__)
>  int get_arch_regnum(const char *name);
> +#endif
> +
>  /*
>   * get_dwarf_regnum - Returns DWARF regnum from register name
>   * name: architecture register name
> -- 
> 2.47.0.rc0.187.ge670bccf7e-goog
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>