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Subject[PATCH 4/7] modpost: refactor find_fromsym() and find_tosym()
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find_fromsym() and find_tosym() are similar - both of them iterate
in the .symtab section and return the nearest symbol.

The difference between them is that find_tosym() allows a negative
distance, but the distance must be less than 20.

Factor out the common part into find_nearest_sym().

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

scripts/mod/modpost.c | 95 ++++++++++++++++---------------------------
1 file changed, 36 insertions(+), 59 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 5a5e802b160c..32d56efe3f3b 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1075,81 +1075,58 @@ static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)
return !is_mapping_symbol(name);
}

-/**
- * Find symbol based on relocation record info.
- * In some cases the symbol supplied is a valid symbol so
- * return refsym. If is_valid_name() == true, we assume this is a valid symbol.
- * In other cases the symbol needs to be looked up in the symbol table
- * based on section and address.
- * **/
-static Elf_Sym *find_tosym(struct elf_info *elf, Elf64_Sword addr,
- Elf_Sym *relsym)
+/* Look up the nearest symbol based on the section and the address */
+static Elf_Sym *find_nearest_sym(struct elf_info *elf, Elf_Addr addr,
+ unsigned int secndx, bool allow_negative,
+ Elf_Addr min_distance)
{
Elf_Sym *sym;
Elf_Sym *near = NULL;
- Elf64_Sword distance = 20;
- Elf64_Sword d;
- unsigned int relsym_secindex;
-
- if (is_valid_name(elf, relsym))
- return relsym;
-
- /*
- * Strive to find a better symbol name, but the resulting name may not
- * match the symbol referenced in the original code.
- */
- relsym_secindex = get_secindex(elf, relsym);
- for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
- if (get_secindex(elf, sym) != relsym_secindex)
- continue;
- if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
- continue;
- if (!is_valid_name(elf, sym))
- continue;
- if (sym->st_value == addr)
- return sym;
- /* Find a symbol nearby - addr are maybe negative */
- d = sym->st_value - addr;
- if (d < 0)
- d = addr - sym->st_value;
- if (d < distance) {
- distance = d;
- near = sym;
- }
- }
- /* We need a close match */
- if (distance < 20)
- return near;
- else
- return NULL;
-}
-
-/*
- * Find symbols before or equal addr and after addr - in the section sec.
- * If we find two symbols with equal offset prefer one with a valid name.
- * The ELF format may have a better way to detect what type of symbol
- * it is, but this works for now.
- **/
-static Elf_Sym *find_fromsym(struct elf_info *elf, Elf_Addr addr,
- unsigned int secndx)
-{
- Elf_Sym *sym;
- Elf_Sym *near = NULL;
- Elf_Addr distance = ~0;
+ Elf_Addr distance;

for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
if (get_secindex(elf, sym) != secndx)
continue;
if (!is_valid_name(elf, sym))
continue;
- if (sym->st_value <= addr && addr - sym->st_value <= distance) {
+
+ if (addr >= sym->st_value)
distance = addr - sym->st_value;
+ else if (allow_negative)
+ distance = sym->st_value - addr;
+ else
+ continue;
+
+ if (distance <= min_distance) {
+ min_distance = distance;
near = sym;
}
+
+ if (min_distance == 0)
+ break;
}
return near;
}

+static Elf_Sym *find_fromsym(struct elf_info *elf, Elf_Addr addr,
+ unsigned int secndx)
+{
+ return find_nearest_sym(elf, addr, secndx, false, ~0);
+}
+
+static Elf_Sym *find_tosym(struct elf_info *elf, Elf_Addr addr, Elf_Sym *sym)
+{
+ /* If the supplied symbol has a valid name, return it */
+ if (is_valid_name(elf, sym))
+ return sym;
+
+ /*
+ * Strive to find a better symbol name, but the resulting name may not
+ * match the symbol referenced in the original code.
+ */
+ return find_nearest_sym(elf, addr, get_secindex(elf, sym), true, 20);
+}
+
static bool is_executable_section(struct elf_info *elf, unsigned int secndx)
{
if (secndx > elf->num_sections)
--
2.39.2
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