kexec: Factor out routine to find a symbol in ELF

The routine to search a symbol in ELF can be shared, so split it out.

Signed-off-by: Pingfan Liu <[email protected]>
Cc: Baoquan He <[email protected]>
Cc: Dave Young <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Philipp Rudo <[email protected]>
To: [email protected]

Author: Pingfan Liu

include/linux/kexec.h

@@ -23,6 +23,10 @@
 #include <uapi/linux/kexec.h>
 #include <linux/verification.h>
 
+#if defined(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) || defined(CONFIG_KEXEC_PE_IMAGE)
+#include <linux/module.h>
+#endif
+
 extern note_buf_t __percpu *crash_notes;
 
 #ifdef CONFIG_CRASH_DUMP
@@ -550,6 +554,10 @@ void set_kexec_sig_enforced(void);
 static inline void set_kexec_sig_enforced(void) {}
 #endif
 
+#if defined(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) || defined(CONFIG_KEXEC_PE_IMAGE)
+const Elf_Sym *elf_find_symbol(const Elf_Ehdr *ehdr, const char *name);
+#endif
+
 #endif /* !defined(__ASSEBMLY__) */
 
 #endif /* LINUX_KEXEC_H */

kernel/kexec_file.c

@@ -880,6 +880,51 @@ static int kexec_calculate_store_digests(struct kimage *image)
 	return ret;
 }
 
+#if defined(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) || defined(CONFIG_KEXEC_PE_IMAGE)
+const Elf_Sym *elf_find_symbol(const Elf_Ehdr *ehdr, const char *name)
+{
+	const Elf_Shdr *sechdrs;
+	const Elf_Sym *syms;
+	const char *strtab;
+	int i, k;
+
+	sechdrs = (void *)ehdr + ehdr->e_shoff;
+
+	for (i = 0; i < ehdr->e_shnum; i++) {
+		if (sechdrs[i].sh_type != SHT_SYMTAB)
+			continue;
+
+		if (sechdrs[i].sh_link >= ehdr->e_shnum)
+			/* Invalid strtab section number */
+			continue;
+		strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
+		syms = (void *)ehdr + sechdrs[i].sh_offset;
+
+		/* Go through symbols for a match */
+		for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
+			if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
+				continue;
+
+			if (strcmp(strtab + syms[k].st_name, name) != 0)
+				continue;
+
+			if (syms[k].st_shndx == SHN_UNDEF ||
+			    syms[k].st_shndx >= ehdr->e_shnum) {
+				pr_debug("Symbol: %s has bad section index %d.\n",
+						name, syms[k].st_shndx);
+				return NULL;
+			}
+
+			/* Found the symbol we are looking for */
+			return &syms[k];
+		}
+	}
+
+	return NULL;
+}
+
+#endif
+
 #ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
 /*
  * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
@@ -1137,49 +1182,10 @@ int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
 static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
 						  const char *name)
 {
-	const Elf_Shdr *sechdrs;
-	const Elf_Ehdr *ehdr;
-	const Elf_Sym *syms;
-	const char *strtab;
-	int i, k;
-
 	if (!pi->ehdr)
 		return NULL;
 
-	ehdr = pi->ehdr;
-	sechdrs = (void *)ehdr + ehdr->e_shoff;
-
-	for (i = 0; i < ehdr->e_shnum; i++) {
-		if (sechdrs[i].sh_type != SHT_SYMTAB)
-			continue;
-
-		if (sechdrs[i].sh_link >= ehdr->e_shnum)
-			/* Invalid strtab section number */
-			continue;
-		strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
-		syms = (void *)ehdr + sechdrs[i].sh_offset;
-
-		/* Go through symbols for a match */
-		for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
-			if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
-				continue;
-
-			if (strcmp(strtab + syms[k].st_name, name) != 0)
-				continue;
-
-			if (syms[k].st_shndx == SHN_UNDEF ||
-			    syms[k].st_shndx >= ehdr->e_shnum) {
-				pr_debug("Symbol: %s has bad section index %d.\n",
-						name, syms[k].st_shndx);
-				return NULL;
-			}
-
-			/* Found the symbol we are looking for */
-			return &syms[k];
-		}
-	}
-
-	return NULL;
+	return elf_find_symbol(pi->ehdr, name);
 }
 
 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)