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powerpc/module: Only try to generate the ftrace_caller() stub once

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Currently we generate the module stub for ftrace_caller() at the bottom
of apply_relocate_add(). However apply_relocate_add() is potentially
called more than once per module, which means we will try to generate
the ftrace_caller() stub multiple times.

Although the current code deals with that correctly, ie. it only
generates a stub the first time, it would be clearer to only try to
generate the stub once.

Note also on first reading it may appear that we generate a different
stub for each section that requires relocation, but that is not the
case. The code in stub_for_addr() that searches for an existing stub
uses sechdrs[me->arch.stubs_section], ie. the single stub section for
this module.

A cleaner approach is to only generate the ftrace_caller() stub once,
from module_finalize(). Although the original code didn't check to see
if the stub was actually generated correctly, it seems prudent to add a
check, so do that. And an additional benefit is we can clean the ifdefs
up a little.

Finally we must propagate the const'ness of some of the pointers passed
to module_finalize(), but that is also an improvement.

Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Torsten Duwe <duwe@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Michael Ellerman 2016-03-03 15:26:54 +11:00
parent a5cab83cd3
commit 136cd3450a
4 changed files with 43 additions and 15 deletions
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9
arch/powerpc/include/asm/module.h
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@ -82,6 +82,15 @@ bool is_module_trampoline(u32 *insns);
int module_trampoline_target(struct module *mod, u32 *trampoline,
unsigned long *target);
#ifdef CONFIG_DYNAMIC_FTRACE
int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs);
#else
static inline int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
{
return 0;
}
#endif
struct exception_table_entry;
void sort_ex_table(struct exception_table_entry *start,
struct exception_table_entry *finish);