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Re: [Qemu-devel] [PATCH] elf: Calculate symbol size if needed


From: Blue Swirl
Subject: Re: [Qemu-devel] [PATCH] elf: Calculate symbol size if needed
Date: Wed, 11 Aug 2010 16:21:10 +0000

On Mon, Aug 9, 2010 at 2:43 PM, Stefan Weil <address@hidden> wrote:
> Symbols with a size of 0 are unusable for the disassembler.
>
> Example:
>
> While running an arm linux kernel, no symbolic names are
> used in qemu.log when the cpu is executing an assembler function.

That is a problem of the assembler function, it should use '.size'
directive like what happens when C code is compiled. And why just ARM?

> Assume that the size of such symbols is the difference to the
> next symbol value.
>
> Signed-off-by: Stefan Weil <address@hidden>
> ---
>  hw/elf_ops.h |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/hw/elf_ops.h b/hw/elf_ops.h
> index 27d1ab9..0bd7235 100644
> --- a/hw/elf_ops.h
> +++ b/hw/elf_ops.h
> @@ -153,6 +153,11 @@ static int glue(load_symbols, SZ)(struct elfhdr *ehdr, 
> int fd, int must_swab,
>         syms = qemu_realloc(syms, nsyms * sizeof(*syms));
>
>         qsort(syms, nsyms, sizeof(*syms), glue(symcmp, SZ));
> +        for (i = 0; i < nsyms - 1; i++) {
> +            if (syms[i].st_size == 0) {
> +                syms[i].st_size = syms[i + 1].st_value - syms[i].st_value;
> +            }
> +        }

The size of the last symbol is not guesstimated, it could be assumed
to be _etext - syms[nsyms].st_value.

>     } else {
>         qemu_free(syms);
>         syms = NULL;
> --
> 1.7.1
>
>
>



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