Re: [Qemu-devel] [PATCH v8 11/23] Add symbol table callback interface to load_elf

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

On 03/02/2018 02:51 PM, Michael Clark wrote:
> The RISC-V HTIF (Host Target Interface) console device requires access
> to the symbol table to locate the 'tohost' and 'fromhost' symbols.
> 
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Michael Clark <mjc@sifive.com>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

> ---
>  hw/core/loader.c     | 18 ++++++++++++++++--
>  include/hw/elf_ops.h | 34 +++++++++++++++++++++-------------
>  include/hw/loader.h  | 17 ++++++++++++++++-
>  3 files changed, 53 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/core/loader.c b/hw/core/loader.c
> index c08f130..1d26c6e 100644
> --- a/hw/core/loader.c
> +++ b/hw/core/loader.c
> @@ -450,6 +450,20 @@ int load_elf_ram(const char *filename,
>                   int clear_lsb, int data_swab, AddressSpace *as,
>                   bool load_rom)
>  {
> +    return load_elf_ram_sym(filename, translate_fn, translate_opaque,
> +                            pentry, lowaddr, highaddr, big_endian,
> +                            elf_machine, clear_lsb, data_swab, as,
> +                            load_rom, NULL);
> +}
> +
> +/* return < 0 if error, otherwise the number of bytes loaded in memory */
> +int load_elf_ram_sym(const char *filename,
> +                     uint64_t (*translate_fn)(void *, uint64_t),
> +                     void *translate_opaque, uint64_t *pentry,
> +                     uint64_t *lowaddr, uint64_t *highaddr, int big_endian,
> +                     int elf_machine, int clear_lsb, int data_swab,
> +                     AddressSpace *as, bool load_rom, symbol_fn_t sym_cb)
> +{
>      int fd, data_order, target_data_order, must_swab, ret = ELF_LOAD_FAILED;
>      uint8_t e_ident[EI_NIDENT];
>  
> @@ -488,11 +502,11 @@ int load_elf_ram(const char *filename,
>      if (e_ident[EI_CLASS] == ELFCLASS64) {
>          ret = load_elf64(filename, fd, translate_fn, translate_opaque, must_swab,
>                           pentry, lowaddr, highaddr, elf_machine, clear_lsb,
> -                         data_swab, as, load_rom);
> +                         data_swab, as, load_rom, sym_cb);
>      } else {
>          ret = load_elf32(filename, fd, translate_fn, translate_opaque, must_swab,
>                           pentry, lowaddr, highaddr, elf_machine, clear_lsb,
> -                         data_swab, as, load_rom);
> +                         data_swab, as, load_rom, sym_cb);
>      }
>  
>   fail:
> diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
> index d192e7e..b6e19e3 100644
> --- a/include/hw/elf_ops.h
> +++ b/include/hw/elf_ops.h
> @@ -105,7 +105,7 @@ static int glue(symcmp, SZ)(const void *s0, const void *s1)
>  }
>  
>  static int glue(load_symbols, SZ)(struct elfhdr *ehdr, int fd, int must_swab,
> -                                  int clear_lsb)
> +                                  int clear_lsb, symbol_fn_t sym_cb)
>  {
>      struct elf_shdr *symtab, *strtab, *shdr_table = NULL;
>      struct elf_sym *syms = NULL;
> @@ -133,10 +133,26 @@ static int glue(load_symbols, SZ)(struct elfhdr *ehdr, int fd, int must_swab,
>  
>      nsyms = symtab->sh_size / sizeof(struct elf_sym);
>  
> +    /* String table */
> +    if (symtab->sh_link >= ehdr->e_shnum) {
> +        goto fail;
> +    }
> +    strtab = &shdr_table[symtab->sh_link];
> +
> +    str = load_at(fd, strtab->sh_offset, strtab->sh_size);
> +    if (!str) {
> +        goto fail;
> +    }
> +
>      i = 0;
>      while (i < nsyms) {
> -        if (must_swab)
> +        if (must_swab) {
>              glue(bswap_sym, SZ)(&syms[i]);
> +        }
> +        if (sym_cb) {
> +            sym_cb(str + syms[i].st_name, syms[i].st_info,
> +                   syms[i].st_value, syms[i].st_size);
> +        }
>          /* We are only interested in function symbols.
>             Throw everything else away.  */
>          if (syms[i].st_shndx == SHN_UNDEF ||
> @@ -163,15 +179,6 @@ static int glue(load_symbols, SZ)(struct elfhdr *ehdr, int fd, int must_swab,
>          }
>      }
>  
> -    /* String table */
> -    if (symtab->sh_link >= ehdr->e_shnum)
> -        goto fail;
> -    strtab = &shdr_table[symtab->sh_link];
> -
> -    str = load_at(fd, strtab->sh_offset, strtab->sh_size);
> -    if (!str)
> -        goto fail;
> -
>      /* Commit */
>      s = g_malloc0(sizeof(*s));
>      s->lookup_symbol = glue(lookup_symbol, SZ);
> @@ -264,7 +271,8 @@ static int glue(load_elf, SZ)(const char *name, int fd,
>                                int must_swab, uint64_t *pentry,
>                                uint64_t *lowaddr, uint64_t *highaddr,
>                                int elf_machine, int clear_lsb, int data_swab,
> -                              AddressSpace *as, bool load_rom)
> +                              AddressSpace *as, bool load_rom,
> +                              symbol_fn_t sym_cb)
>  {
>      struct elfhdr ehdr;
>      struct elf_phdr *phdr = NULL, *ph;
> @@ -329,7 +337,7 @@ static int glue(load_elf, SZ)(const char *name, int fd,
>      if (pentry)
>     	*pentry = (uint64_t)(elf_sword)ehdr.e_entry;
>  
> -    glue(load_symbols, SZ)(&ehdr, fd, must_swab, clear_lsb);
> +    glue(load_symbols, SZ)(&ehdr, fd, must_swab, clear_lsb, sym_cb);
>  
>      size = ehdr.e_phnum * sizeof(phdr[0]);
>      if (lseek(fd, ehdr.e_phoff, SEEK_SET) != ehdr.e_phoff) {
> diff --git a/include/hw/loader.h b/include/hw/loader.h
> index 5edbe02..7b05e8b 100644
> --- a/include/hw/loader.h
> +++ b/include/hw/loader.h
> @@ -64,7 +64,7 @@ int load_image_gzipped(const char *filename, hwaddr addr, uint64_t max_sz);
>  #define ELF_LOAD_WRONG_ENDIAN -4
>  const char *load_elf_strerror(int error);
>  
> -/** load_elf_ram:
> +/** load_elf_ram_sym:
>   * @filename: Path of ELF file
>   * @translate_fn: optional function to translate load addresses
>   * @translate_opaque: opaque data passed to @translate_fn
> @@ -81,6 +81,7 @@ const char *load_elf_strerror(int error);
>   * @as: The AddressSpace to load the ELF to. The value of address_space_memory
>   *      is used if nothing is supplied here.
>   * @load_rom : Load ELF binary as ROM
> + * @sym_cb: Callback function for symbol table entries
>   *
>   * Load an ELF file's contents to the emulated system's address space.
>   * Clients may optionally specify a callback to perform address
> @@ -93,6 +94,20 @@ const char *load_elf_strerror(int error);
>   * If @elf_machine is EM_NONE then the machine type will be read from the
>   * ELF header and no checks will be carried out against the machine type.
>   */
> +typedef void (*symbol_fn_t)(const char *st_name, int st_info,
> +                            uint64_t st_value, uint64_t st_size);
> +
> +int load_elf_ram_sym(const char *filename,
> +                     uint64_t (*translate_fn)(void *, uint64_t),
> +                     void *translate_opaque, uint64_t *pentry,
> +                     uint64_t *lowaddr, uint64_t *highaddr, int big_endian,
> +                     int elf_machine, int clear_lsb, int data_swab,
> +                     AddressSpace *as, bool load_rom, symbol_fn_t sym_cb);
> +
> +/** load_elf_ram:
> + * Same as load_elf_ram_sym(), but doesn't allow the caller to specify a
> + * symbol callback function
> + */
>  int load_elf_ram(const char *filename,
>                   uint64_t (*translate_fn)(void *, uint64_t),
>                   void *translate_opaque, uint64_t *pentry, uint64_t *lowaddr,
>