Remove memory allocation for ELF sections

Since the section headers of ELF are continuous, all headers can be
accessed by getting the starting address, so there is no need to
allocate memory for this.

Remove implementation of get_elf_section_headers

src/elf.c

@@ -355,37 +355,6 @@ bool elf_open(elf_t *e, const char *path)
     return true;
 }
 
-struct Elf32_Shdr **get_elf_section_headers(elf_t *e)
-{
-    struct Elf32_Ehdr *elf_hdr = (struct Elf32_Ehdr *) e->hdr;
-    Elf32_Half shnum = elf_hdr->e_shnum;
-    off_t offset = elf_hdr->e_shoff;
-    uint8_t *buf = e->raw_data + offset;
-
-    struct Elf32_Shdr **shdrs = malloc(sizeof(struct Elf32_Shdr) * shnum);
-    if (!shdrs)
-        return NULL;
-
-    for (int i = 0; i < shnum; i++) {
-        struct Elf32_Shdr *shdr = (struct Elf32_Shdr *) shdrs + i;
-        struct Elf32_Shdr *_shdr =
-            (struct Elf32_Shdr *) (buf + sizeof(struct Elf32_Shdr) * i);
-
-        shdr->sh_name = _shdr->sh_name;
-        shdr->sh_type = _shdr->sh_type;
-        shdr->sh_flags = _shdr->sh_flags;
-        shdr->sh_addr = _shdr->sh_addr;
-        shdr->sh_offset = _shdr->sh_offset;
-        shdr->sh_size = _shdr->sh_size;
-        shdr->sh_link = _shdr->sh_link;
-        shdr->sh_info = _shdr->sh_info;
-        shdr->sh_addralign = _shdr->sh_addralign;
-        shdr->sh_entsize = _shdr->sh_entsize;
-    }
-
-    return shdrs;
-}
-
 struct Elf32_Ehdr *get_elf_header(elf_t *e)
 {
     return (struct Elf32_Ehdr *) e->hdr;

src/elf.h

@@ -152,6 +152,3 @@ struct Elf32_Ehdr *get_elf_header(elf_t *e);
 
 /* get the first byte of ELF raw data */
 uint8_t *get_elf_first_byte(elf_t *e);
-
-/* get all of the ELF section headers */
-struct Elf32_Shdr **get_elf_section_headers(elf_t *e);

tools/rv_histogram.c

@@ -241,13 +241,11 @@ int main(int argc, char *args[])
     }
 
     struct Elf32_Ehdr *hdr = get_elf_header(e);
-    struct Elf32_Shdr **shdrs = get_elf_section_headers(e);
-    if (!shdrs) {
-        fprintf(stderr, "malloc for section headers failed\n");
-        return 1;
-    }
-
     uintptr_t *elf_first_byte = (uintptr_t *) get_elf_first_byte(e);
+    struct Elf32_Shdr **shdrs =
+        (struct Elf32_Shdr **) (elf_first_byte +
+                                hdr->e_shoff / sizeof(uintptr_t));
+
     rv_insn_t ir;
     bool res;
 
@@ -312,7 +310,6 @@ int main(int argc, char *args[])
         print_hist_stats(rv_insn_stats, N_RV_INSNS + 1);
     }
 
-    free(shdrs);
     elf_delete(e);
 
     return 0;