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modpost, kallsyms: Treat add '$'-prefixed symbols as mapping symbols
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Trying to restrict the '$'-prefix change to RISC-V caused some fallout,
so let's just treat all those symbols as special.

Fixes: c05780e ("module: Ignore RISC-V mapping symbols too")
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Palmer Dabbelt <[email protected]>
Reviewed-by: Masahiro Yamada <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>
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palmer-dabbelt authored and mcgrof committed Jul 24, 2023
1 parent 9ce170c commit ff09f6f
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Showing 3 changed files with 4 additions and 16 deletions.
16 changes: 2 additions & 14 deletions include/linux/module_symbol.h
Original file line number Diff line number Diff line change
Expand Up @@ -3,25 +3,13 @@
#define _LINUX_MODULE_SYMBOL_H

/* This ignores the intensely annoying "mapping symbols" found in ELF files. */
static inline int is_mapping_symbol(const char *str, int is_riscv)
static inline int is_mapping_symbol(const char *str)
{
if (str[0] == '.' && str[1] == 'L')
return true;
if (str[0] == 'L' && str[1] == '0')
return true;
/*
* RISC-V defines various special symbols that start with "$".  The
* mapping symbols, which exist to differentiate between incompatible
* instruction encodings when disassembling, show up all over the place
* and are generally not meant to be treated like other symbols.  So
* just ignore any of the special symbols.
*/
if (is_riscv)
return str[0] == '$';

return str[0] == '$' &&
(str[1] == 'a' || str[1] == 'd' || str[1] == 't' || str[1] == 'x')
&& (str[2] == '\0' || str[2] == '.');
return str[0] == '$';
}

#endif /* _LINUX_MODULE_SYMBOL_H */
2 changes: 1 addition & 1 deletion kernel/module/kallsyms.c
Original file line number Diff line number Diff line change
Expand Up @@ -289,7 +289,7 @@ static const char *find_kallsyms_symbol(struct module *mod,
* and inserted at a whim.
*/
if (*kallsyms_symbol_name(kallsyms, i) == '\0' ||
is_mapping_symbol(kallsyms_symbol_name(kallsyms, i), IS_ENABLED(CONFIG_RISCV)))
is_mapping_symbol(kallsyms_symbol_name(kallsyms, i)))
continue;

if (thisval <= addr && thisval > bestval) {
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2 changes: 1 addition & 1 deletion scripts/mod/modpost.c
Original file line number Diff line number Diff line change
Expand Up @@ -1052,7 +1052,7 @@ static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)

if (!name || !strlen(name))
return 0;
return !is_mapping_symbol(name, elf->hdr->e_machine == EM_RISCV);
return !is_mapping_symbol(name);
}

/* Look up the nearest symbol based on the section and the address */
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