Commit c93d4f6e authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/ftrace: Add module_trampoline_target() for PPC32 



module_trampoline_target() is used by __ftrace_modify_call().

Implement it for PPC32 so that CONFIG_DYNAMIC_FTRACE_WITH_REGS
can be activated on PPC32 as well.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/42345f464fb465f0fc76f3090e250be8fc1729f0.1635423081.git.christophe.leroy@csgroup.eu
parent 88670fdb

arch/powerpc/kernel/module_32.c

+25 −0
Original line number Original line Diff line number Diff line
@@ -273,6 +273,31 @@ int apply_relocate_add(Elf32_Shdr *sechdrs, 
}

}





#ifdef CONFIG_DYNAMIC_FTRACE

#ifdef CONFIG_DYNAMIC_FTRACE

int module_trampoline_target(struct module *mod, unsigned long addr,

			     unsigned long *target)

{

	unsigned int jmp[4];



	/* Find where the trampoline jumps to */

	if (copy_from_kernel_nofault(jmp, (void *)addr, sizeof(jmp)))

		return -EFAULT;



	/* verify that this is what we expect it to be */

	if ((jmp[0] & 0xffff0000) != PPC_RAW_LIS(_R12, 0) ||

	    (jmp[1] & 0xffff0000) != PPC_RAW_ADDI(_R12, _R12, 0) ||

	    jmp[2] != PPC_RAW_MTCTR(_R12) ||

	    jmp[3] != PPC_RAW_BCTR())

		return -EINVAL;



	addr = (jmp[1] & 0xffff) | ((jmp[0] & 0xffff) << 16);

	if (addr & 0x8000)

		addr -= 0x10000;



	*target = addr;



	return 0;

}



int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)

int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)

{

{

	module->arch.tramp = do_plt_call(module->core_layout.base,

	module->arch.tramp = do_plt_call(module->core_layout.base,

arch/powerpc/kernel/trace/ftrace.c

+4 −33
Original line number Original line Diff line number Diff line
@@ -222,9 +222,8 @@ __ftrace_make_nop(struct module *mod, 
		  struct dyn_ftrace *rec, unsigned long addr)

		  struct dyn_ftrace *rec, unsigned long addr)

{

{

	struct ppc_inst op;

	struct ppc_inst op;

	unsigned int jmp[4];

	unsigned long ip = rec->ip;

	unsigned long ip = rec->ip;

	unsigned long tramp;

	unsigned long tramp, ptr;





	if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))

	if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))

		return -EFAULT;

		return -EFAULT;
@@ -238,41 +237,13 @@ __ftrace_make_nop(struct module *mod, 
	/* lets find where the pointer goes */

	/* lets find where the pointer goes */

	tramp = find_bl_target(ip, op);

	tramp = find_bl_target(ip, op);





	/*

	 * On PPC32 the trampoline looks like:

	 *  0x3d, 0x80, 0x00, 0x00  lis r12,sym@ha

	 *  0x39, 0x8c, 0x00, 0x00  addi r12,r12,sym@l

	 *  0x7d, 0x89, 0x03, 0xa6  mtctr r12

	 *  0x4e, 0x80, 0x04, 0x20  bctr

	 */



	pr_devel("ip:%lx jumps to %lx", ip, tramp);



	/* Find where the trampoline jumps to */

	/* Find where the trampoline jumps to */

	if (copy_from_kernel_nofault(jmp, (void *)tramp, sizeof(jmp))) {

	if (module_trampoline_target(mod, tramp, &ptr)) {

		pr_err("Failed to read %lx\n", tramp);

		pr_err("Failed to get trampoline target\n");

		return -EFAULT;

		return -EFAULT;

	}

	}





	pr_devel(" %08x %08x ", jmp[0], jmp[1]);

	if (ptr != addr) {



	/* verify that this is what we expect it to be */

	if (((jmp[0] & 0xffff0000) != 0x3d800000) ||

	    ((jmp[1] & 0xffff0000) != 0x398c0000) ||

	    (jmp[2] != 0x7d8903a6) ||

	    (jmp[3] != 0x4e800420)) {

		pr_err("Not a trampoline\n");

		return -EINVAL;

	}



	tramp = (jmp[1] & 0xffff) |

		((jmp[0] & 0xffff) << 16);

	if (tramp & 0x8000)

		tramp -= 0x10000;



	pr_devel(" %lx ", tramp);



	if (tramp != addr) {

		pr_err("Trampoline location %08lx does not match addr\n",

		pr_err("Trampoline location %08lx does not match addr\n",

		       tramp);

		       tramp);

		return -EINVAL;

		return -EINVAL;