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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>
This commit is contained in:
Anton Blanchard 2014-04-03 20:00:43 +11:00
parent 47f86b4e07
commit 83775b8566
2 changed files with 47 additions and 5 deletions
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1
arch/powerpc/include/asm/module.h
View File

@ -78,6 +78,7 @@ struct mod_arch_specific {
# endif /* MODULE */
#endif
bool is_module_trampoline(u32 *insns);
struct exception_table_entry;
void sort_ex_table(struct exception_table_entry *start,

51
arch/powerpc/kernel/module_64.c
View File

@ -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);