Commit f2ec8d9a authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
Browse files

kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_descriptor() 

~15 years ago kprobes grew the 'arch_deref_entry_point()' __weak function:

  3d7e3382: ("jprobes: make jprobes a little safer for users")

But this is just open-coded dereference_symbol_descriptor() in essence, and
its obscure nature was causing bugs.

Just use the real thing and remove arch_deref_entry_point().

Link: https://lkml.kernel.org/r/163163043630.489837.7924988885652708696.stgit@devnote2



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Tested-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent a7fe2378

arch/ia64/kernel/kprobes.c

+0 −5
Original line number Diff line number Diff line
@@ -891,11 +891,6 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self, 
	return ret;

}



unsigned long arch_deref_entry_point(void *entry)

{

	return ((struct fnptr *)entry)->ip;

}



static struct kprobe trampoline_p = {

	.pre_handler = trampoline_probe_handler

};

arch/powerpc/kernel/kprobes.c

+0 −11
Original line number Diff line number Diff line
@@ -542,17 +542,6 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 
}

NOKPROBE_SYMBOL(kprobe_fault_handler);



unsigned long arch_deref_entry_point(void *entry)

{

#ifdef PPC64_ELF_ABI_v1

	if (!kernel_text_address((unsigned long)entry))

		return ppc_global_function_entry(entry);

	else

#endif

		return (unsigned long)entry;

}

NOKPROBE_SYMBOL(arch_deref_entry_point);



static struct kprobe trampoline_p = {

	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,

	.pre_handler = trampoline_probe_handler

include/linux/kprobes.h

+0 −1
Original line number Diff line number Diff line
@@ -381,7 +381,6 @@ int register_kprobe(struct kprobe *p); 
void unregister_kprobe(struct kprobe *p);

int register_kprobes(struct kprobe **kps, int num);

void unregister_kprobes(struct kprobe **kps, int num);

unsigned long arch_deref_entry_point(void *);



int register_kretprobe(struct kretprobe *rp);

void unregister_kretprobe(struct kretprobe *rp);

kernel/kprobes.c

+1 −6
Original line number Diff line number Diff line
@@ -1861,11 +1861,6 @@ static struct notifier_block kprobe_exceptions_nb = { 
	.priority = 0x7fffffff /* we need to be notified first */

};



unsigned long __weak arch_deref_entry_point(void *entry)

{

	return (unsigned long)entry;

}



#ifdef CONFIG_KRETPROBES



unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
@@ -2327,7 +2322,7 @@ static int __init populate_kprobe_blacklist(unsigned long *start, 
	int ret;



	for (iter = start; iter < end; iter++) {

		entry = arch_deref_entry_point((void *)*iter);

		entry = (unsigned long)dereference_symbol_descriptor((void *)*iter);

		ret = kprobe_add_ksym_blacklist(entry);

		if (ret == -EINVAL)

			continue;

lib/error-inject.c

+2 −1
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/mutex.h>

#include <linux/list.h>

#include <linux/slab.h>

#include <asm/sections.h>



/* Whitelist of symbols that can be overridden for error injection. */

static LIST_HEAD(error_injection_list);
@@ -64,7 +65,7 @@ static void populate_error_injection_list(struct error_injection_entry *start, 


	mutex_lock(&ei_mutex);

	for (iter = start; iter < end; iter++) {

		entry = arch_deref_entry_point((void *)iter->addr);

		entry = (unsigned long)dereference_symbol_descriptor((void *)iter->addr);



		if (!kernel_text_address(entry) ||

		    !kallsyms_lookup_size_offset(entry, &size, &offset)) {