elf/symbol: Symbol link to program headers

GElf_Sym belongs to a section, and this section could belongs to more
than one Phdrs.

    $ ./src/tests/ulpatch_test -f Elf.for_each_symbol -v
    ...
     0x000000000051c120 424     OBJECT   LOCAL    INTERNAL     16   x86_64_reloc_map
      Type             Offset             VirtAddr           PhysAddr
                       FileSize           MemSize            Flags    Align
      LOAD             0x00000000000f4000 0x00000000004f4000 00000000004f4000
                       0x0000000000045d98 0x0000000000045d98 R        00001000
     0x000000000054b4a0 904     OBJECT   GLOBAL   INTERNAL     22   x86_64_pei_vec
      Type             Offset             VirtAddr           PhysAddr
                       FileSize           MemSize            Flags    Align
      LOAD             0x000000000013a020 0x000000000053a020 000000000053a020
                       0x00000000000290f0 0x000000000002a5b8 RW       00001000
      GNU_RELRO        0x000000000013a020 0x000000000053a020 000000000053a020
                       0x0000000000014fe0 0x0000000000014fe0 R        00000001

Signed-off-by: Rong Tao <[email protected]>

src/elf/elf_api.h

@@ -81,6 +81,13 @@ struct symbol {
 	char *name;
 	GElf_Sym sym;
 
+	/**
+	 * If symbol from ELF file, point to elf file phdrs. If symbol from
+	 * VMA mem, point to vma's elf phdrs, and used to locate VMA.
+	 */
+	int nphdrs;
+	GElf_Phdr *phdrs;
+
 	/**
 	 * Maybe belongs to a VMA, and this vma is ELF format, which is the
 	 * leader of all other PT_LOAD vmas.

src/elf/symbol.c

@@ -367,14 +367,43 @@ int for_each_symbol(struct elf_file *elf, void (*handler)(struct elf_file *,
 /* Insert OK, return 0, else return -1 */
 int link_symbol(struct elf_file *elf, struct symbol *s)
 {
-	struct rb_node *node = rb_insert_node(&elf->elf_file_symbols, &s->node,
-					      cmp_symbol_name,
-					      (unsigned long)s);
+	int i, nphdrs;
+	struct rb_node *node;
+	GElf_Section sec = s->sym.st_shndx;
+	GElf_Shdr *shdr = &elf->shdrs[sec];
+
+	if (!is_undef_symbol(&s->sym)) {
+		GElf_Phdr *phdr, *phdrs;
+
+		nphdrs = 0;
+		phdrs = malloc(sizeof(GElf_Phdr) * elf->phdrnum);
+
+		for (i = 0; i < elf->phdrnum; i++) {
+			phdr = &elf->phdrs[i];
+			if (shdr->sh_offset >= phdr->p_offset &&
+				shdr->sh_offset + shdr->sh_size <=
+					phdr->p_offset + phdr->p_filesz) {
+				memcpy(&phdrs[nphdrs], phdr, sizeof(GElf_Phdr));
+				nphdrs++;
+			}
+		}
+		if (nphdrs) {
+			s->nphdrs = nphdrs;
+			s->phdrs = malloc(sizeof(GElf_Phdr) * nphdrs);
+			memcpy(s->phdrs, phdrs, sizeof(GElf_Phdr) * nphdrs);
+		}
+		free(phdrs);
+	}
+
+	node = rb_insert_node(&elf->elf_file_symbols, &s->node,
+			      cmp_symbol_name, (unsigned long)s);
 	return node ? -1 : 0;
 }
 
 void free_symbol(struct symbol *s)
 {
+	if (s->phdrs)
+		free(s->phdrs);
 	free(s->name);
 	free(s);
 }

src/tests/elf/symbol.c

@@ -49,8 +49,15 @@ static const struct symbol_t symbols[] = {
 static void print_elf_symbol(struct elf_file *elf, struct symbol *sym,
 			     void *arg)
 {
+	int i;
 	static bool firstline = true;
+
 	fprint_sym(stdout, &sym->sym, sym->name, NULL, firstline);
+	if (sym->nphdrs > 0) {
+		for (i = 0; i < sym->nphdrs; i++)
+			print_phdr(stdout, &sym->phdrs[i], i == 0);
+	}
+
 	firstline = false;
 }
 

src/utils/task.c

@@ -830,6 +830,11 @@ int task_vma_link_symbol(struct symbol *s, struct vm_area_struct *leader)
 		fprint_sym(get_log_fp(), &s->sym, s->name, NULL, true);
 
 	s->vma = vma;
+
+	/**
+	 * TODO: Get the symbol belongs to which phdrs.
+	 */
+
 	node = rb_insert_node(&task->vma_symbols, &s->node, cmp_symbol_name,
 			      (unsigned long)s);
 	if (unlikely(node))