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modpost: fix extable entry size calculation.

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As Guenter pointed out, we were never really calculating the extable entry
size because the pointer arithmetic was simply wrong.  We want to check
we're handling the second relocation in __ex_table to infer an entry size,
but we were using (void*) pointers instead of Elf_Rel[a]* ones.

This fixes the problem by moving that check in the caller (since we can
deal with different types of relocations) and add is_second_extable_reloc()
to make the whole thing more readable.

Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Quentin Casasnovas 2015-04-16 13:05:36 +09:30 committed by Rusty Russell
parent d3df4de7eb
commit e84048aa17
1 changed files with 10 additions and 6 deletions
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16
scripts/mod/modpost.c
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@ -1511,8 +1511,7 @@ static int is_executable_section(struct elf_info* elf, unsigned int section_inde
* to know the sizeof(struct exception_table_entry) for the target architecture.
*/
static unsigned int extable_entry_size = 0;
static void find_extable_entry_size(const char* const sec, const Elf_Rela* r,
const void* start, const void* cur)
static void find_extable_entry_size(const char* const sec, const Elf_Rela* r)
{
/*
* If we're currently checking the second relocation within __ex_table,
@ -1523,10 +1522,10 @@ static void find_extable_entry_size(const char* const sec, const Elf_Rela* r,
* seems to go with different sized types. Not pretty but better than
* hard-coding the size for every architecture..
*/
if (!extable_entry_size && cur == start + 1 &&
strcmp("__ex_table", sec) == 0)
if (!extable_entry_size)
extable_entry_size = r->r_offset * 2;
}
static inline bool is_extable_fault_address(Elf_Rela *r)
{
/*
@ -1541,6 +1540,9 @@ static inline bool is_extable_fault_address(Elf_Rela *r)
(r->r_offset % extable_entry_size == 0));
}
#define is_second_extable_reloc(Start, Cur, Sec) \
(((Cur) == (Start) + 1) && (strcmp("__ex_table", (Sec)) == 0))
static void report_extable_warnings(const char* modname, struct elf_info* elf,
const struct sectioncheck* const mismatch,
Elf_Rela* r, Elf_Sym* sym,
@ -1769,7 +1771,8 @@ static void section_rela(const char *modname, struct elf_info *elf,
/* Skip special sections */
if (is_shndx_special(sym->st_shndx))
continue;
find_extable_entry_size(fromsec, &r, start, rela);
if (is_second_extable_reloc(start, rela, fromsec))
find_extable_entry_size(fromsec, &r);
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
}
@ -1828,7 +1831,8 @@ static void section_rel(const char *modname, struct elf_info *elf,
/* Skip special sections */
if (is_shndx_special(sym->st_shndx))
continue;
find_extable_entry_size(fromsec, &r, start, rel);
if (is_second_extable_reloc(start, rel, fromsec))
find_extable_entry_size(fromsec, &r);
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
}