linux-kernel - [PATCH 2/2] modpost: factor out the common boilerplate of section

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Date:   Sun,  1 Oct 2023 14:47:36 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     linux-kbuild@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>
Subject: [PATCH 2/2] modpost: factor out the common boilerplate of section_rel(a)

The first few lines of section_rel() and section_rela() are the same.
They both retrieve the index of the section to which the relocaton
applies, and skip known-good sections. This common code should be moved
to check_sec_ref().

Avoid ugly casts when computing 'start' and 'stop', and also make the
Elf_Rel and Elf_Rela pointers const.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 scripts/mod/modpost.c | 50 ++++++++++++++++++++++---------------------
 1 file changed, 26 insertions(+), 24 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 15d78fe152ac..0e18fe617ed1 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1425,17 +1425,10 @@ static void get_rel_type_and_sym(struct elf_info *elf, uint64_t r_info,
 }
 
 static void section_rela(struct module *mod, struct elf_info *elf,
-			 Elf_Shdr *sechdr)
+			 unsigned int fsecndx, const char *fromsec,
+			 const Elf_Rela *start, const Elf_Rela *stop)
 {
-	Elf_Rela *rela;
-	unsigned int fsecndx = sechdr->sh_info;
-	const char *fromsec = sec_name(elf, fsecndx);
-	Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset;
-	Elf_Rela *stop  = (void *)start + sechdr->sh_size;
-
-	/* if from section (name) is know good then skip it */
-	if (match(fromsec, section_white_list))
-		return;
+	const Elf_Rela *rela;
 
 	for (rela = start; rela < stop; rela++) {
 		Elf_Addr taddr, r_offset;
@@ -1465,17 +1458,10 @@ static void section_rela(struct module *mod, struct elf_info *elf,
 }
 
 static void section_rel(struct module *mod, struct elf_info *elf,
-			Elf_Shdr *sechdr)
+			unsigned int fsecndx, const char *fromsec,
+			const Elf_Rel *start, const Elf_Rel *stop)
 {
-	Elf_Rel *rel;
-	unsigned int fsecndx = sechdr->sh_info;
-	const char *fromsec = sec_name(elf, fsecndx);
-	Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset;
-	Elf_Rel *stop  = (void *)start + sechdr->sh_size;
-
-	/* if from section (name) is know good then skip it */
-	if (match(fromsec, section_white_list))
-		return;
+	const Elf_Rel *rel;
 
 	for (rel = start; rel < stop; rel++) {
 		Elf_Sym *tsym;
@@ -1530,10 +1516,26 @@ static void check_sec_ref(struct module *mod, struct elf_info *elf)
 
 		check_section(mod->name, elf, sechdr);
 		/* We want to process only relocation sections and not .init */
-		if (sechdr->sh_type == SHT_RELA)
-			section_rela(mod, elf, sechdr);
-		else if (sechdr->sh_type == SHT_REL)
-			section_rel(mod, elf, sechdr);
+		if (sechdr->sh_type == SHT_REL || sechdr->sh_type == SHT_RELA) {
+			/* section to which the relocation applies */
+			unsigned int secndx = sechdr->sh_info;
+			const char *secname = sec_name(elf, secndx);
+			const void *start, *stop;
+
+			/* If the section is known good, skip it */
+			if (match(secname, section_white_list))
+				continue;
+
+			start = sym_get_data_by_offset(elf, i, 0);
+			stop = start + sechdr->sh_size;
+
+			if (sechdr->sh_type == SHT_RELA)
+				section_rela(mod, elf, secndx, secname,
+					     start, stop);
+			else
+				section_rel(mod, elf, secndx, secname,
+					    start, stop);
+		}
 	}
 }
 
-- 
2.39.2