Commit b860b934 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/ftrace: remove dead code 



ftrace_shared_hotpatch_trampoline() never returns NULL,
therefore quite a bit of code can be removed.

Acked-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 9e1ff307

arch/s390/kernel/ftrace.c

+6 −80
Original line number Diff line number Diff line
@@ -80,17 +80,6 @@ asm( 


#ifdef CONFIG_MODULES

static char *ftrace_plt;



asm(

	"	.data\n"

	"ftrace_plt_template:\n"

	"	basr	%r1,%r0\n"

	"	lg	%r1,0f-.(%r1)\n"

	"	br	%r1\n"

	"0:	.quad	ftrace_caller\n"

	"ftrace_plt_template_end:\n"

	"	.previous\n"

);

#endif /* CONFIG_MODULES */



static const char *ftrace_shared_hotpatch_trampoline(const char **end)
@@ -116,7 +105,7 @@ static const char *ftrace_shared_hotpatch_trampoline(const char **end) 


bool ftrace_need_init_nop(void)

{

	return ftrace_shared_hotpatch_trampoline(NULL);

	return true;

}



int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
@@ -175,28 +164,6 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 
	return 0;

}



static void ftrace_generate_nop_insn(struct ftrace_insn *insn)

{

	/* brcl 0,0 */

	insn->opc = 0xc004;

	insn->disp = 0;

}



static void ftrace_generate_call_insn(struct ftrace_insn *insn,

				      unsigned long ip)

{

	unsigned long target;



	/* brasl r0,ftrace_caller */

	target = FTRACE_ADDR;

#ifdef CONFIG_MODULES

	if (is_module_addr((void *)ip))

		target = (unsigned long)ftrace_plt;

#endif /* CONFIG_MODULES */

	insn->opc = 0xc005;

	insn->disp = (target - ip) / 2;

}



static void brcl_disable(void *brcl)

{

	u8 op = 0x04; /* set mask field to zero */
@@ -207,26 +174,10 @@ static void brcl_disable(void *brcl) 
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,

		    unsigned long addr)

{

	struct ftrace_insn orig, new, old;



	if (ftrace_shared_hotpatch_trampoline(NULL)) {

	brcl_disable((void *)rec->ip);

	return 0;

}



	if (copy_from_kernel_nofault(&old, (void *) rec->ip, sizeof(old)))

		return -EFAULT;

	/* Replace ftrace call with a nop. */

	ftrace_generate_call_insn(&orig, rec->ip);

	ftrace_generate_nop_insn(&new);



	/* Verify that the to be replaced code matches what we expect. */

	if (memcmp(&orig, &old, sizeof(old)))

		return -EINVAL;

	s390_kernel_write((void *) rec->ip, &new, sizeof(new));

	return 0;

}



static void brcl_enable(void *brcl)

{

	u8 op = 0xf4; /* set mask field to all ones */
@@ -236,26 +187,10 @@ static void brcl_enable(void *brcl) 


int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)

{

	struct ftrace_insn orig, new, old;



	if (ftrace_shared_hotpatch_trampoline(NULL)) {

	brcl_enable((void *)rec->ip);

	return 0;

}



	if (copy_from_kernel_nofault(&old, (void *) rec->ip, sizeof(old)))

		return -EFAULT;

	/* Replace nop with an ftrace call. */

	ftrace_generate_nop_insn(&orig);

	ftrace_generate_call_insn(&new, rec->ip);



	/* Verify that the to be replaced code matches what we expect. */

	if (memcmp(&orig, &old, sizeof(old)))

		return -EINVAL;

	s390_kernel_write((void *) rec->ip, &new, sizeof(new));

	return 0;

}



int ftrace_update_ftrace_func(ftrace_func_t func)

{

	ftrace_func = func;
@@ -269,10 +204,7 @@ int __init ftrace_dyn_arch_init(void) 


void arch_ftrace_update_code(int command)

{

	if (ftrace_shared_hotpatch_trampoline(NULL))

	ftrace_modify_all_code(command);

	else

		ftrace_run_stop_machine(command);

}



static void __ftrace_sync(void *dummy)
@@ -281,10 +213,8 @@ static void __ftrace_sync(void *dummy) 


int ftrace_arch_code_modify_post_process(void)

{

	if (ftrace_shared_hotpatch_trampoline(NULL)) {

	/* Send SIGP to the other CPUs, so they see the new code. */

	smp_call_function(__ftrace_sync, NULL, 1);

	}

	return 0;

}
@@ -299,10 +229,6 @@ static int __init ftrace_plt_init(void) 
		panic("cannot allocate ftrace plt\n");



	start = ftrace_shared_hotpatch_trampoline(&end);

	if (!start) {

		start = ftrace_plt_template;

		end = ftrace_plt_template_end;

	}

	memcpy(ftrace_plt, start, end - start);

	set_memory_ro((unsigned long)ftrace_plt, 1);

	return 0;