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| author | Michael Ellerman <mpe@ellerman.id.au> | 2016-03-03 07:26:54 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2016-03-07 06:53:53 +0300 |
| commit | 136cd3450af8092f30d0e289806f08ac2aeee38f (patch) | |
| tree | cd2a9d14ff7dcf8e80620aff347c1e303b881270 /arch/powerpc/kernel/module_64.c | |
| parent | a5cab83cd3d2d75d3893276cb5f27e163484ef04 (diff) | |
| download | linux-136cd3450af8092f30d0e289806f08ac2aeee38f.tar.xz | |
powerpc/module: Only try to generate the ftrace_caller() stub once
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>
Diffstat (limited to 'arch/powerpc/kernel/module_64.c')
| -rw-r--r-- | arch/powerpc/kernel/module_64.c | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index ac64ffdb52c8..599c753c7960 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -413,7 +413,7 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr, /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the value maximum span in an instruction which uses a signed offset) */ -static inline unsigned long my_r2(Elf64_Shdr *sechdrs, struct module *me) +static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me) { return sechdrs[me->arch.toc_section].sh_addr + 0x8000; } @@ -426,7 +426,7 @@ static inline unsigned long my_r2(Elf64_Shdr *sechdrs, struct module *me) #define PPC_HA(v) PPC_HI ((v) + 0x8000) /* Patch stub to reference function and correct r2 value. */ -static inline int create_stub(Elf64_Shdr *sechdrs, +static inline int create_stub(const Elf64_Shdr *sechdrs, struct ppc64_stub_entry *entry, unsigned long addr, struct module *me) @@ -452,7 +452,7 @@ static inline int create_stub(Elf64_Shdr *sechdrs, /* Create stub to jump to function described in this OPD/ptr: we need the stub to set up the TOC ptr (r2) for the function. */ -static unsigned long stub_for_addr(Elf64_Shdr *sechdrs, +static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs, unsigned long addr, struct module *me) { @@ -693,12 +693,18 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, } } + return 0; +} + #ifdef CONFIG_DYNAMIC_FTRACE - me->arch.toc = my_r2(sechdrs, me); - me->arch.tramp = stub_for_addr(sechdrs, - (unsigned long)ftrace_caller, - me); -#endif +int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs) +{ + mod->arch.toc = my_r2(sechdrs, mod); + mod->arch.tramp = stub_for_addr(sechdrs, (unsigned long)ftrace_caller, mod); + + if (!mod->arch.tramp) + return -ENOENT; return 0; } +#endif |