libelf: abolish elf_sval and elf_access_signed

These are not used anywhere.

This is part of the fix to a security issue, XSA-55.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Chuck Anderson <chuck.anderson@oracle.com>

xen/common/libelf/libelf-tools.c

@@ -48,34 +48,6 @@ uint64_t elf_access_unsigned(struct elf_binary * elf, const void *ptr,
     }
 }
 
-int64_t elf_access_signed(struct elf_binary *elf, const void *ptr,
-                          uint64_t offset, size_t size)
-{
-    int need_swap = elf_swap(elf);
-    const int8_t *s8;
-    const int16_t *s16;
-    const int32_t *s32;
-    const int64_t *s64;
-
-    switch ( size )
-    {
-    case 1:
-        s8 = ptr + offset;
-        return *s8;
-    case 2:
-        s16 = ptr + offset;
-        return need_swap ? bswap_16(*s16) : *s16;
-    case 4:
-        s32 = ptr + offset;
-        return need_swap ? bswap_32(*s32) : *s32;
-    case 8:
-        s64 = ptr + offset;
-        return need_swap ? bswap_64(*s64) : *s64;
-    default:
-        return 0;
-    }
-}
-
 uint64_t elf_round_up(struct elf_binary *elf, uint64_t addr)
 {
     int elf_round = (elf_64bit(elf) ? 8 : 4) - 1;

xen/include/xen/libelf.h

@@ -136,23 +136,12 @@ struct elf_binary {
                            offsetof(typeof(*(str)),e32.elem),           \
                            sizeof((str)->e32.elem)))
 
-#define elf_sval(elf, str, elem)                                        \
-    ((ELFCLASS64 == (elf)->class)                                       \
-     ? elf_access_signed((elf), (str),                                  \
-                         offsetof(typeof(*(str)),e64.elem),             \
-                         sizeof((str)->e64.elem))                       \
-     : elf_access_signed((elf), (str),                                  \
-                         offsetof(typeof(*(str)),e32.elem),             \
-                         sizeof((str)->e32.elem)))
-
 #define elf_size(elf, str)                              \
     ((ELFCLASS64 == (elf)->class)                       \
      ? sizeof((str)->e64) : sizeof((str)->e32))
 
 uint64_t elf_access_unsigned(struct elf_binary *elf, const void *ptr,
                              uint64_t offset, size_t size);
-int64_t elf_access_signed(struct elf_binary *elf, const void *ptr,
-                          uint64_t offset, size_t size);
 
 uint64_t elf_round_up(struct elf_binary *elf, uint64_t addr);