powerpc/kprobes: Convert __kprobes to NOKPROBE_SYMBOL()

Along similar lines as commit 9326638c ("kprobes, x86: Use NOKPROBE_SYMBOL()
instead of __kprobes annotation"), convert __kprobes annotation to either
NOKPROBE_SYMBOL() or nokprobe_inline. The latter forces inlining, in which case
the caller needs to be added to NOKPROBE_SYMBOL().

Also:
 - blacklist arch_deref_entry_point(), and
 - convert a few regular inlines to nokprobe_inline in lib/sstep.c

A key benefit is the ability to detect such symbols as being
blacklisted. Before this patch:

  $ cat /sys/kernel/debug/kprobes/blacklist | grep read_mem
  $ perf probe read_mem
  Failed to write event: Invalid argument
    Error: Failed to add events.
  $ dmesg | tail -1
  [ 3736.112815] Could not insert probe at _text+10014968: -22

After patch:
  $ cat /sys/kernel/debug/kprobes/blacklist | grep read_mem
  0xc000000000072b50-0xc000000000072d20	read_mem
  $ perf probe read_mem
  read_mem is blacklisted function, skip it.
  Added new events:
    (null):(null)        (on read_mem)
    probe:read_mem       (on read_mem)

  You can now use it in all perf tools, such as:

	  perf record -e probe:read_mem -aR sleep 1

  $ grep " read_mem" /proc/kallsyms
  c000000000072b50 t read_mem
  c0000000005f3b40 t read_mem
  $ cat /sys/kernel/debug/kprobes/list
  c0000000005f3b48  k  read_mem+0x8    [DISABLED]
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
[mpe: Minor change log formatting, fix up some conflicts]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/kprobes.c

@@ -42,7 +42,7 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
 struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
 
-int __kprobes arch_prepare_kprobe(struct kprobe *p)
+int arch_prepare_kprobe(struct kprobe *p)
 {
 	int ret = 0;
 	kprobe_opcode_t insn = *p->addr;
@@ -74,30 +74,34 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
 	p->ainsn.boostable = 0;
 	return ret;
 }
+NOKPROBE_SYMBOL(arch_prepare_kprobe);
 
-void __kprobes arch_arm_kprobe(struct kprobe *p)
+void arch_arm_kprobe(struct kprobe *p)
 {
 	*p->addr = BREAKPOINT_INSTRUCTION;
 	flush_icache_range((unsigned long) p->addr,
 			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }
+NOKPROBE_SYMBOL(arch_arm_kprobe);
 
-void __kprobes arch_disarm_kprobe(struct kprobe *p)
+void arch_disarm_kprobe(struct kprobe *p)
 {
 	*p->addr = p->opcode;
 	flush_icache_range((unsigned long) p->addr,
 			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }
+NOKPROBE_SYMBOL(arch_disarm_kprobe);
 
-void __kprobes arch_remove_kprobe(struct kprobe *p)
+void arch_remove_kprobe(struct kprobe *p)
 {
 	if (p->ainsn.insn) {
 		free_insn_slot(p->ainsn.insn, 0);
 		p->ainsn.insn = NULL;
 	}
 }
+NOKPROBE_SYMBOL(arch_remove_kprobe);
 
-static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+static nokprobe_inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 {
 	enable_single_step(regs);
 
@@ -110,37 +114,37 @@ static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 	regs->nip = (unsigned long)p->ainsn.insn;
 }
 
-static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+static nokprobe_inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
 	kcb->prev_kprobe.kp = kprobe_running();
 	kcb->prev_kprobe.status = kcb->kprobe_status;
 	kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr;
 }
 
-static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+static nokprobe_inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
 	__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
 	kcb->kprobe_status = kcb->prev_kprobe.status;
 	kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;
 }
 
-static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+static nokprobe_inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
 				struct kprobe_ctlblk *kcb)
 {
 	__this_cpu_write(current_kprobe, p);
 	kcb->kprobe_saved_msr = regs->msr;
 }
 
-void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
-				      struct pt_regs *regs)
+void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
 	ri->ret_addr = (kprobe_opcode_t *)regs->link;
 
 	/* Replace the return addr with trampoline addr */
 	regs->link = (unsigned long)kretprobe_trampoline;
 }
+NOKPROBE_SYMBOL(arch_prepare_kretprobe);
 
-int __kprobes kprobe_handler(struct pt_regs *regs)
+int kprobe_handler(struct pt_regs *regs)
 {
 	struct kprobe *p;
 	int ret = 0;
@@ -273,6 +277,7 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
 	preempt_enable_no_resched();
 	return ret;
 }
+NOKPROBE_SYMBOL(kprobe_handler);
 
 /*
  * Function return probe trampoline:
@@ -290,8 +295,7 @@ asm(".global kretprobe_trampoline\n"
 /*
  * Called when the probe at kretprobe trampoline is hit
  */
-static int __kprobes trampoline_probe_handler(struct kprobe *p,
-						struct pt_regs *regs)
+static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 {
 	struct kretprobe_instance *ri = NULL;
 	struct hlist_head *head, empty_rp;
@@ -360,6 +364,7 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
 	 */
 	return 1;
 }
+NOKPROBE_SYMBOL(trampoline_probe_handler);
 
 /*
  * Called after single-stepping.  p->addr is the address of the
@@ -369,7 +374,7 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
  * single-stepped a copy of the instruction.  The address of this
  * copy is p->ainsn.insn.
  */
-int __kprobes kprobe_post_handler(struct pt_regs *regs)
+int kprobe_post_handler(struct pt_regs *regs)
 {
 	struct kprobe *cur = kprobe_running();
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -409,8 +414,9 @@ int __kprobes kprobe_post_handler(struct pt_regs *regs)
 
 	return 1;
 }
+NOKPROBE_SYMBOL(kprobe_post_handler);
 
-int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
 	struct kprobe *cur = kprobe_running();
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -473,13 +479,15 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 	}
 	return 0;
 }
+NOKPROBE_SYMBOL(kprobe_fault_handler);
 
 unsigned long arch_deref_entry_point(void *entry)
 {
 	return ppc_global_function_entry(entry);
 }
+NOKPROBE_SYMBOL(arch_deref_entry_point);
 
-int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 {
 	struct jprobe *jp = container_of(p, struct jprobe, kp);
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -496,17 +504,20 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 
 	return 1;
 }
+NOKPROBE_SYMBOL(setjmp_pre_handler);
 
-void __used __kprobes jprobe_return(void)
+void __used jprobe_return(void)
 {
 	asm volatile("trap" ::: "memory");
 }
+NOKPROBE_SYMBOL(jprobe_return);
 
-static void __used __kprobes jprobe_return_end(void)
+static void __used jprobe_return_end(void)
 {
-};
+}
+NOKPROBE_SYMBOL(jprobe_return_end);
 
-int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
@@ -519,6 +530,7 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 	preempt_enable_no_resched();
 	return 1;
 }
+NOKPROBE_SYMBOL(longjmp_break_handler);
 
 static struct kprobe trampoline_p = {
 	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
@@ -530,10 +542,11 @@ int __init arch_init_kprobes(void)
 	return register_kprobe(&trampoline_p);
 }
 
-int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+int arch_trampoline_kprobe(struct kprobe *p)
 {
 	if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
 		return 1;
 
 	return 0;
 }
+NOKPROBE_SYMBOL(arch_trampoline_kprobe);

arch/powerpc/lib/code-patching.c

@@ -8,6 +8,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/kprobes.h>
 #include <linux/vmalloc.h>
 #include <linux/init.h>
 #include <linux/mm.h>
@@ -59,7 +60,7 @@ bool is_offset_in_branch_range(long offset)
  * Helper to check if a given instruction is a conditional branch
  * Derived from the conditional checks in analyse_instr()
  */
-bool __kprobes is_conditional_branch(unsigned int instr)
+bool is_conditional_branch(unsigned int instr)
 {
 	unsigned int opcode = instr >> 26;
 
@@ -75,6 +76,7 @@ bool __kprobes is_conditional_branch(unsigned int instr)
 	}
 	return false;
 }
+NOKPROBE_SYMBOL(is_conditional_branch);
 
 unsigned int create_branch(const unsigned int *addr,
 			   unsigned long target, int flags)