[PATCH] remove modpost false warnings on ARM
This patch stops "modpost" from issuing erroneous modpost warnings on ARM
builds, which it's been doing since since maybe last summer. A canonical
example would be driver method table entries:
WARNING: <path> - Section mismatch: reference to .exit.text:<name>_remove
from .data after '$d' (at offset 0x4)
That "$d" symbol is generated by tools conformant with ARM ABI specs; in
this case it's a symbol **in the middle of** a "<name>_driver" struct.
The erroneous warnings appear to be issued because "modpost" whitelists
references from "<name>_driver" data into init and exit sections ... but
doesn't know should also include those "$d" mapping symbols, which are not
otherwise associated with "<name>_driver" symbols.
This patch prevents the modpost symbol lookup code from ever returning
those mapping symbols, so it will return a whitelisted symbol instead.
Then things work as expected.
Now to revert various code-bloating "fixes" that got merged because of this
modpost bug....
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Roman Zippel <zippel@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 569e684..c4b5398 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -686,6 +686,30 @@
return NULL;
}
+static inline int is_arm_mapping_symbol(const char *str)
+{
+ return str[0] == '$' && strchr("atd", str[1])
+ && (str[2] == '\0' || str[2] == '.');
+}
+
+/*
+ * If there's no name there, ignore it; likewise, ignore it if it's
+ * one of the magic symbols emitted used by current ARM tools.
+ *
+ * Otherwise if find_symbols_between() returns those symbols, they'll
+ * fail the whitelist tests and cause lots of false alarms ... fixable
+ * only by merging __exit and __init sections into __text, bloating
+ * the kernel (which is especially evil on embedded platforms).
+ */
+static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)
+{
+ const char *name = elf->strtab + sym->st_name;
+
+ if (!name || !strlen(name))
+ return 0;
+ return !is_arm_mapping_symbol(name);
+}
+
/*
* 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.
@@ -714,16 +738,15 @@
symsec = secstrings + elf->sechdrs[sym->st_shndx].sh_name;
if (strcmp(symsec, sec) != 0)
continue;
+ if (!is_valid_name(elf, sym))
+ continue;
if (sym->st_value <= addr) {
if ((addr - sym->st_value) < beforediff) {
beforediff = addr - sym->st_value;
*before = sym;
}
else if ((addr - sym->st_value) == beforediff) {
- /* equal offset, valid name? */
- const char *name = elf->strtab + sym->st_name;
- if (name && strlen(name))
- *before = sym;
+ *before = sym;
}
}
else
@@ -733,10 +756,7 @@
*after = sym;
}
else if ((sym->st_value - addr) == afterdiff) {
- /* equal offset, valid name? */
- const char *name = elf->strtab + sym->st_name;
- if (name && strlen(name))
- *after = sym;
+ *after = sym;
}
}
}
