[PATCH] remove modpost false warnings on ARM (da68d61f) · Commits · 戴 / test

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>

scripts/mod/modpost.c

+28 −8

Original line number	Diff line number	Diff line
		@@ -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.
		@@ -714,15 +738,14 @@ 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;
		}
		}
		@@ -733,9 +756,6 @@ 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;
		}
		}

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