kernel/kexec_file.c: remove unneeded variables in kexec_purgatory_setup_sechdrs

The main loop currently uses quite a lot of variables to update the
section headers.  Some of them are unnecessary.  So clean them up a
little.

Link: http://lkml.kernel.org/r/20180321112751.22196-9-prudo@linux.vnet.ibm.comSigned-off-by: NPhilipp Rudo <prudo@linux.vnet.ibm.com>
Acked-by: NDave Young <dyoung@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/kexec_file.c

@@ -785,12 +785,8 @@ static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
 static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
 					 struct kexec_buf *kbuf)
 {
-	unsigned long curr_load_addr;
-	unsigned long load_addr;
 	unsigned long bss_addr;
 	unsigned long offset;
-	unsigned char *buf_addr;
-	unsigned char *src;
 	Elf_Shdr *sechdrs;
 	int i;
 
@@ -823,20 +819,18 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
 						sechdrs[i].sh_offset;
 	}
 
-	/* Load SHF_ALLOC sections */
-	buf_addr = kbuf->buffer;
-	load_addr = curr_load_addr = kbuf->mem;
-	bss_addr = load_addr + kbuf->bufsz;
+	offset = 0;
+	bss_addr = kbuf->mem + kbuf->bufsz;
 	kbuf->image->start = pi->ehdr->e_entry;
 
 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
 		unsigned long align;
+		void *src, *dst;
 
 		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
 			continue;
 
 		align = sechdrs[i].sh_addralign;
-
 		if (sechdrs[i].sh_type == SHT_NOBITS) {
 			bss_addr = ALIGN(bss_addr, align);
 			sechdrs[i].sh_addr = bss_addr;
@@ -844,31 +838,27 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
 			continue;
 		}
 
-		curr_load_addr = ALIGN(curr_load_addr, align);
-		offset = curr_load_addr - load_addr;
-		/* We already modifed ->sh_offset to keep src addr */
-		src = (char *)sechdrs[i].sh_offset;
-		memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
-
+		offset = ALIGN(offset, align);
 		if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
 		    pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
 		    pi->ehdr->e_entry < (sechdrs[i].sh_addr
 					 + sechdrs[i].sh_size)) {
 			kbuf->image->start -= sechdrs[i].sh_addr;
-			kbuf->image->start += curr_load_addr;
+			kbuf->image->start += kbuf->mem + offset;
 		}
 
-		/* Store load address and source address of section */
-		sechdrs[i].sh_addr = curr_load_addr;
+		src = (void *)sechdrs[i].sh_offset;
+		dst = pi->purgatory_buf + offset;
+		memcpy(dst, src, sechdrs[i].sh_size);
+
+		sechdrs[i].sh_addr = kbuf->mem + offset;
 
 		/*
 		 * This section got copied to temporary buffer. Update
 		 * ->sh_offset accordingly.
 		 */
-		sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
-
-		/* Advance to the next address */
-		curr_load_addr += sechdrs[i].sh_size;
+		sechdrs[i].sh_offset = (unsigned long)dst;
+		offset += sechdrs[i].sh_size;
 	}
 
 	return 0;