powerpc/optprobes: Minimise casts

nip is already an unsigned long, no cast needed.

op_callback_addr and emulate_step_addr are kprobe_opcode_t *.
There value is obtained with ppc_kallsyms_lookup_name() which
returns 'unsigned long', and there values are used create_branch()
which expects 'unsigned long'. So change them to 'unsigned long'
to avoid casting them back and forth.

can_optimize() used p->addr several times as 'unsigned long'.
Use a local 'unsigned long' variable and avoid casting multiple times.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e03192a6d4123242a275e71ce2ba0bb4d90700c1.1621516826.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
index 88e2057..07edc42 100644 (file)
--- a/arch/powerpc/kernel/optprobes.c
+++ b/arch/powerpc/kernel/optprobes.c
@@ -55,6 +55,7 @@ static unsigned long can_optimize(struct kprobe *p)
        struct pt_regs regs;
        struct instruction_op op;
        unsigned long nip = 0;
+       unsigned long addr = (unsigned long)p->addr;
 
        /*
         * kprobe placed for kretprobe during boot time
@@ -62,7 +63,7 @@ static unsigned long can_optimize(struct kprobe *p)
         * So further checks can be skipped.
         */
        if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
-               return (unsigned long)p->addr + sizeof(kprobe_opcode_t);
+               return addr + sizeof(kprobe_opcode_t);
 
        /*
         * We only support optimizing kernel addresses, but not
@@ -70,11 +71,11 @@ static unsigned long can_optimize(struct kprobe *p)
         *
         * FIXME: Optimize kprobes placed in module addresses.
         */
-       if (!is_kernel_addr((unsigned long)p->addr))
+       if (!is_kernel_addr(addr))
                return 0;
 
        memset(&regs, 0, sizeof(struct pt_regs));
-       regs.nip = (unsigned long)p->addr;
+       regs.nip = addr;
        regs.trap = 0x0;
        regs.msr = MSR_KERNEL;
 
@@ -184,7 +185,8 @@ static void patch_imm_load_insns(unsigned long val, int reg, kprobe_opcode_t *ad
 int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
 {
        struct ppc_inst branch_op_callback, branch_emulate_step, temp;
-       kprobe_opcode_t *op_callback_addr, *emulate_step_addr, *buff;
+       unsigned long op_callback_addr, emulate_step_addr;
+       kprobe_opcode_t *buff;
        long b_offset;
        unsigned long nip, size;
        int rc, i;
@@ -212,8 +214,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
                goto error;
 
        /* Check if the return address is also within 32MB range */
-       b_offset = (unsigned long)(buff + TMPL_RET_IDX) -
-                       (unsigned long)nip;
+       b_offset = (unsigned long)(buff + TMPL_RET_IDX) - nip;
        if (!is_offset_in_branch_range(b_offset))
                goto error;
 
@@ -236,20 +237,18 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
        /*
         * 2. branch to optimized_callback() and emulate_step()
         */
-       op_callback_addr = (kprobe_opcode_t *)ppc_kallsyms_lookup_name("optimized_callback");
-       emulate_step_addr = (kprobe_opcode_t *)ppc_kallsyms_lookup_name("emulate_step");
+       op_callback_addr = ppc_kallsyms_lookup_name("optimized_callback");
+       emulate_step_addr = ppc_kallsyms_lookup_name("emulate_step");
        if (!op_callback_addr || !emulate_step_addr) {
                WARN(1, "Unable to lookup optimized_callback()/emulate_step()\n");
                goto error;
        }
 
        rc = create_branch(&branch_op_callback, buff + TMPL_CALL_HDLR_IDX,
-                          (unsigned long)op_callback_addr,
-                          BRANCH_SET_LINK);
+                          op_callback_addr, BRANCH_SET_LINK);
 
        rc |= create_branch(&branch_emulate_step, buff + TMPL_EMULATE_IDX,
-                           (unsigned long)emulate_step_addr,
-                           BRANCH_SET_LINK);
+                           emulate_step_addr, BRANCH_SET_LINK);
 
        if (rc)
                goto error;