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Commit 83775b85 authored by Anton Blanchard's avatar Anton Blanchard
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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: default avatarAnton Blanchard <anton@samba.org>
parent 47f86b4e

arch/powerpc/include/asm/module.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

arch/powerpc/kernel/module_64.c

+46 −5
Original line number Diff line number Diff line
@@ -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);