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author | Anton Blanchard <anton@samba.org> | 2014-04-03 20:00:43 +1100 |
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committer | Anton Blanchard <anton@samba.org> | 2014-04-23 10:05:34 +1000 |
commit | 83775b85668a85036973c71264a959236e7becbd (patch) | |
tree | 3a751b74a5fa580b3371ff747a626970a52db089 /arch/powerpc/kernel | |
parent | 47f86b4e07afd4652ab0b092cbf493bf8b96559e (diff) | |
download | linux-83775b85668a85036973c71264a959236e7becbd.tar.gz linux-83775b85668a85036973c71264a959236e7becbd.tar.bz2 linux-83775b85668a85036973c71264a959236e7becbd.zip |
powerpc/modules: Create is_module_trampoline()
ftrace has way too much knowledge of our kernel module trampoline
layout hidden inside it. Create is_module_trampoline() that can
abstract this away inside the module loader code.
Signed-off-by: Anton Blanchard <anton@samba.org>
Diffstat (limited to 'arch/powerpc/kernel')
-rw-r--r-- | arch/powerpc/kernel/module_64.c | 51 |
1 files changed, 46 insertions, 5 deletions
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 042360135260..4db5ecdc06e6 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -22,6 +22,7 @@ #include <linux/vmalloc.h> #include <linux/ftrace.h> #include <linux/bug.h> +#include <linux/uaccess.h> #include <asm/module.h> #include <asm/firmware.h> #include <asm/code-patching.h> @@ -102,7 +103,9 @@ static unsigned int local_entry_offset(const Elf64_Sym *sym) jump, actually, to reset r2 (TOC+0x8000). */ struct ppc64_stub_entry { - /* 28 byte jump instruction sequence (7 instructions) */ + /* 28 byte jump instruction sequence (7 instructions). We only + * need 6 instructions on ABIv2 but we always allocate 7 so + * so we don't have to modify the trampoline load instruction. */ u32 jump[7]; u32 unused; /* Data for the above code */ @@ -122,8 +125,8 @@ struct ppc64_stub_entry * end of the stub code, and patch the stub address (32-bits relative * to the TOC ptr, r2) into the stub. */ -static struct ppc64_stub_entry ppc64_stub = -{ .jump = { + +static u32 ppc64_stub_insns[] = { 0x3d620000, /* addis r11,r2, <high> */ 0x396b0000, /* addi r11,r11, <low> */ /* Save current r2 value in magic place on the stack. */ @@ -135,7 +138,45 @@ static struct ppc64_stub_entry ppc64_stub = #endif 0x7d8903a6, /* mtctr r12 */ 0x4e800420 /* bctr */ -} }; +}; + +#ifdef CONFIG_DYNAMIC_FTRACE + +static u32 ppc64_stub_mask[] = { + 0xffff0000, + 0xffff0000, + 0xffffffff, + 0xffffffff, +#if !defined(_CALL_ELF) || _CALL_ELF != 2 + 0xffffffff, +#endif + 0xffffffff, + 0xffffffff +}; + +bool is_module_trampoline(u32 *p) +{ + unsigned int i; + u32 insns[ARRAY_SIZE(ppc64_stub_insns)]; + + BUILD_BUG_ON(sizeof(ppc64_stub_insns) != sizeof(ppc64_stub_mask)); + + if (probe_kernel_read(insns, p, sizeof(insns))) + return -EFAULT; + + for (i = 0; i < ARRAY_SIZE(ppc64_stub_insns); i++) { + u32 insna = insns[i]; + u32 insnb = ppc64_stub_insns[i]; + u32 mask = ppc64_stub_mask[i]; + + if ((insna & mask) != (insnb & mask)) + return false; + } + + return true; +} + +#endif /* Count how many different 24-bit relocations (different symbol, different addend) */ @@ -350,7 +391,7 @@ static inline int create_stub(Elf64_Shdr *sechdrs, { long reladdr; - *entry = ppc64_stub; + memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns)); /* Stub uses address relative to r2. */ reladdr = (unsigned long)entry - my_r2(sechdrs, me); |