openwrt/target/linux/generic/backport-5.4/030-modpost-add-a-helper-to-get-data-pointed-by-a-symbol.patch

From afa0459daa7b08c7b2c879705b69d39b734a11d0 Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Fri, 15 Nov 2019 02:42:21 +0900
Subject: [PATCH] modpost: add a helper to get data pointed by a symbol

When CONFIG_MODULE_REL_CRCS is enabled, the value of __crc_* is not
an absolute value, but the address to the CRC data embedded in the
.rodata section.

Getting the data pointed by the symbol value is somewhat complex.
Split it out into a new helper, sym_get_data().

I will reuse it to refactor namespace_from_kstrtabns() in the next
commit.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
 scripts/mod/modpost.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -312,6 +312,18 @@ static const char *sec_name(struct elf_i
 	return sech_name(elf, &elf->sechdrs[secindex]);
 }
 
+static void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym)
+{
+	Elf_Shdr *sechdr = &info->sechdrs[sym->st_shndx];
+	unsigned long offset;
+
+	offset = sym->st_value;
+	if (info->hdr->e_type != ET_REL)
+		offset -= sechdr->sh_addr;
+
+	return (void *)info->hdr + sechdr->sh_offset + offset;
+}
+
 #define strstarts(str, prefix) (strncmp(str, prefix, strlen(prefix)) == 0)
 
 static enum export export_from_secname(struct elf_info *elf, unsigned int sec)
@@ -701,10 +713,7 @@ static void handle_modversions(struct mo
 			unsigned int *crcp;
 
 			/* symbol points to the CRC in the ELF object */
-			crcp = (void *)info->hdr + sym->st_value +
-			       info->sechdrs[sym->st_shndx].sh_offset -
-			       (info->hdr->e_type != ET_REL ?
-				info->sechdrs[sym->st_shndx].sh_addr : 0);
+			crcp = sym_get_data(info, sym);
 			crc = TO_NATIVE(*crcp);
 		}
 		sym_update_crc(symname + strlen("__crc_"), mod, crc,