[PATCH v3 2/3] module/kallsyms: Refactor current symbol filtering into is_kept_symbol()

[Tiezhu Yang]

Currently, the loops in layout_symtab() and add_kallsyms() duplicate the
exact same checks (i == 0 || is_livepatch_module() || is_core_symbol())
to determine whether a symbol should be preserved in the module's core
symbol table.

Rename is_core_symbol() to is_kept_symbol() and move the entire checking
logic inside it, including the special handlers for the first symbol and
livepatch modules.

No functional change.

Suggested-by: Petr Pavlu <petr.pavlu@xxxxxxxx>
Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
---
 kernel/module/kallsyms.c | 54 ++++++++++++++++++++--------------------
 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index a595f8cd29b2..ff8d904afe56 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -75,23 +75,26 @@ static char elf_type(const Elf_Sym *sym, const struct load_info *info)
 	return '?';
 }
 
-static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs,
-			   unsigned int shnum, unsigned int pcpundx)
+static bool is_kept_symbol(struct module *mod, const struct load_info *info,
+			   unsigned int symnum, const Elf_Sym *src)
 {
 	const Elf_Shdr *sec;
 	enum mod_mem_type type;
 
+	if (symnum == 0 || is_livepatch_module(mod))
+		return true;
+
 	if (src->st_shndx == SHN_UNDEF ||
-	    src->st_shndx >= shnum ||
+	    src->st_shndx >= info->hdr->e_shnum ||
 	    !src->st_name)
 		return false;
 
 #ifdef CONFIG_KALLSYMS_ALL
-	if (src->st_shndx == pcpundx)
+	if (src->st_shndx == info->index.pcpu)
 		return true;
 #endif
 
-	sec = sechdrs + src->st_shndx;
+	sec = info->sechdrs + src->st_shndx;
 	type = sec->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT;
 	if (!(sec->sh_flags & SHF_ALLOC)
 #ifndef CONFIG_KALLSYMS_ALL
@@ -130,12 +133,11 @@ void layout_symtab(struct module *mod, struct load_info *info)
 
 	/* Compute total space required for the core symbols' strtab. */
 	for (ndst = i = 0; i < nsrc; i++) {
-		if (i == 0 || is_livepatch_module(mod) ||
-		    is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum,
-				   info->index.pcpu)) {
-			strtab_size += strlen(&info->strtab[src[i].st_name]) + 1;
-			ndst++;
-		}
+		if (!is_kept_symbol(mod, info, i, src + i))
+			continue;
+
+		strtab_size += strlen(&info->strtab[src[i].st_name]) + 1;
+		ndst++;
 	}
 
 	/* Append room for core symbols at end of core part. */
@@ -197,23 +199,21 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
 	strtab_size = info->core_typeoffs - info->stroffs;
 	src = kallsyms->symtab;
 	for (ndst = i = 0; i < kallsyms->num_symtab; i++) {
+		ssize_t ret;
+
 		kallsyms->typetab[i] = elf_type(src + i, info);
-		if (i == 0 || is_livepatch_module(mod) ||
-		    is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum,
-				   info->index.pcpu)) {
-			ssize_t ret;
-
-			mod->core_kallsyms.typetab[ndst] =
-				kallsyms->typetab[i];
-			dst[ndst] = src[i];
-			dst[ndst++].st_name = s - mod->core_kallsyms.strtab;
-			ret = strscpy(s, &kallsyms->strtab[src[i].st_name],
-				      strtab_size);
-			if (ret < 0)
-				break;
-			s += ret + 1;
-			strtab_size -= ret + 1;
-		}
+
+		if (!is_kept_symbol(mod, info, i, src + i))
+			continue;
+
+		mod->core_kallsyms.typetab[ndst] = kallsyms->typetab[i];
+		dst[ndst] = src[i];
+		dst[ndst++].st_name = s - mod->core_kallsyms.strtab;
+		ret = strscpy(s, &kallsyms->strtab[src[i].st_name], strtab_size);
+		if (ret < 0)
+			break;
+		s += ret + 1;
+		strtab_size -= ret + 1;
 	}
 
 	/* Set up to point into init section. */
-- 
2.42.0