From da68d61f89e275260cc993a0d4a39e63700098fb Mon Sep 17 00:00:00 2001 From: David Brownell Date: Tue, 20 Feb 2007 13:58:16 -0800 Subject: [PATCH] [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: - Section mismatch: reference to .exit.text:_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 "_driver" struct. The erroneous warnings appear to be issued because "modpost" whitelists references from "_driver" data into init and exit sections ... but doesn't know should also include those "$d" mapping symbols, which are not otherwise associated with "_driver" symbols. This patch prevents the modpost symbol lookup code from ever returning those mapping symbols, so it will return a whitelisted symbol instead. Then things work as expected. Now to revert various code-bloating "fixes" that got merged because of this modpost bug.... Signed-off-by: David Brownell Acked-by: Rusty Russell Cc: Roman Zippel Acked-by: Sam Ravnborg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- scripts/mod/modpost.c | 36 ++++++++++++++++++++++++++++-------- 1 file changed, 28 insertions(+), 8 deletions(-) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 569e68410d7a..c4b5398687b8 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -686,6 +686,30 @@ static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf_Addr addr, return NULL; } +static inline int is_arm_mapping_symbol(const char *str) +{ + return str[0] == '$' && 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 @@ static void find_symbols_between(struct elf_info *elf, Elf_Addr addr, 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 @@ static void find_symbols_between(struct elf_info *elf, Elf_Addr addr, *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; } } } -- 2.20.1