powerpc: Don't use 'struct ppc_inst' to reference instruction location

'struct ppc_inst' is an internal representation of an instruction, but
in-memory instructions are and will remain a table of 'u32' forever.

Replace all 'struct ppc_inst *' used for locating an instruction in
memory by 'u32 *'. This removes a lot of undue casts to 'struct
ppc_inst *'.

It also helps locating ab-use of 'struct ppc_inst' dereference.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fix ppc_inst_next(), use u32 instead of unsigned int]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7062722b087228e42cbd896e39bfdf526d6a340a.1621516826.git.christophe.leroy@csgroup.eu

1 files changed, 8 insertions, 9 deletions

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index e8c2a6373157..b19dfc45f75c 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -107,7 +107,7 @@ int arch_prepare_kprobe(struct kprobe *p)
 {
 	int ret = 0;
 	struct kprobe *prev;
-	struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->addr);
+	struct ppc_inst insn = ppc_inst_read(p->addr);
 
 	if ((unsigned long)p->addr & 0x03) {
 		printk("Attempt to register kprobe at an unaligned address\n");
@@ -116,15 +116,14 @@ int arch_prepare_kprobe(struct kprobe *p)
 		printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n");
 		ret = -EINVAL;
 	} else if ((unsigned long)p->addr & ~PAGE_MASK &&
-		   ppc_inst_prefixed(ppc_inst_read((struct ppc_inst *)(p->addr - 1)))) {
+		   ppc_inst_prefixed(ppc_inst_read(p->addr - 1))) {
 		printk("Cannot register a kprobe on the second word of prefixed instruction\n");
 		ret = -EINVAL;
 	}
 	preempt_disable();
 	prev = get_kprobe(p->addr - 1);
 	preempt_enable_no_resched();
-	if (prev &&
-	    ppc_inst_prefixed(ppc_inst_read((struct ppc_inst *)prev->ainsn.insn))) {
+	if (prev && ppc_inst_prefixed(ppc_inst_read(prev->ainsn.insn))) {
 		printk("Cannot register a kprobe on the second word of prefixed instruction\n");
 		ret = -EINVAL;
 	}
@@ -138,7 +137,7 @@ int arch_prepare_kprobe(struct kprobe *p)
 	}
 
 	if (!ret) {
-		patch_instruction((struct ppc_inst *)p->ainsn.insn, insn);
+		patch_instruction(p->ainsn.insn, insn);
 		p->opcode = ppc_inst_val(insn);
 	}
 
@@ -149,13 +148,13 @@ NOKPROBE_SYMBOL(arch_prepare_kprobe);
 
 void arch_arm_kprobe(struct kprobe *p)
 {
-	patch_instruction((struct ppc_inst *)p->addr, ppc_inst(BREAKPOINT_INSTRUCTION));
+	patch_instruction(p->addr, ppc_inst(BREAKPOINT_INSTRUCTION));
 }
 NOKPROBE_SYMBOL(arch_arm_kprobe);
 
 void arch_disarm_kprobe(struct kprobe *p)
 {
-	patch_instruction((struct ppc_inst *)p->addr, ppc_inst(p->opcode));
+	patch_instruction(p->addr, ppc_inst(p->opcode));
 }
 NOKPROBE_SYMBOL(arch_disarm_kprobe);
 
@@ -228,7 +227,7 @@ NOKPROBE_SYMBOL(arch_prepare_kretprobe);
 static int try_to_emulate(struct kprobe *p, struct pt_regs *regs)
 {
 	int ret;
-	struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->ainsn.insn);
+	struct ppc_inst insn = ppc_inst_read(p->ainsn.insn);
 
 	/* regs->nip is also adjusted if emulate_step returns 1 */
 	ret = emulate_step(regs, insn);
@@ -439,7 +438,7 @@ int kprobe_post_handler(struct pt_regs *regs)
 	if (!cur || user_mode(regs))
 		return 0;
 
-	len = ppc_inst_len(ppc_inst_read((struct ppc_inst *)cur->ainsn.insn));
+	len = ppc_inst_len(ppc_inst_read(cur->ainsn.insn));
 	/* make sure we got here for instruction we have a kprobe on */
 	if (((unsigned long)cur->ainsn.insn + len) != regs->nip)
 		return 0;