powerpc: Use a function for reading instructions

Prefixed instructions will mean there are instructions of different
length. As a result dereferencing a pointer to an instruction will not
necessarily give the desired result. Introduce a function for reading
instructions from memory into the instruction data type.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-13-jniethe5@gmail.com

diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
index f602ca9..f9cbb24 100644 (file)
--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h
@@ -27,6 +27,11 @@ static inline struct ppc_inst ppc_inst_swab(struct ppc_inst x)
        return ppc_inst(swab32(ppc_inst_val(x)));
 }
 
+static inline struct ppc_inst ppc_inst_read(const struct ppc_inst *ptr)
+{
+       return *ptr;
+}
+
 static inline bool ppc_inst_equal(struct ppc_inst x, struct ppc_inst y)
 {
        return ppc_inst_val(x) == ppc_inst_val(y);

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index a08ae58..f64312d 100644 (file)
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -106,7 +106,7 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
 int arch_prepare_kprobe(struct kprobe *p)
 {
        int ret = 0;
-       struct ppc_inst insn = *(struct ppc_inst *)p->addr;
+       struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->addr);
 
        if ((unsigned long)p->addr & 0x03) {
                printk("Attempt to register kprobe at an unaligned address\n");
@@ -127,7 +127,7 @@ int arch_prepare_kprobe(struct kprobe *p)
        if (!ret) {
                memcpy(p->ainsn.insn, p->addr,
                                MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
-               p->opcode = *p->addr;
+               p->opcode = ppc_inst_val(insn);
                flush_icache_range((unsigned long)p->ainsn.insn,
                        (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
        }
@@ -217,7 +217,7 @@ NOKPROBE_SYMBOL(arch_prepare_kretprobe);
 static int try_to_emulate(struct kprobe *p, struct pt_regs *regs)
 {
        int ret;
-       struct ppc_inst insn = *(struct ppc_inst *)p->ainsn.insn;
+       struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->ainsn.insn);
 
        /* regs->nip is also adjusted if emulate_step returns 1 */
        ret = emulate_step(regs, insn);

diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c
index 08b355f..c32af49 100644 (file)
--- a/arch/powerpc/kernel/mce_power.c
+++ b/arch/powerpc/kernel/mce_power.c
@@ -378,7 +378,7 @@ static int mce_find_instr_ea_and_phys(struct pt_regs *regs, uint64_t *addr,
        pfn = addr_to_pfn(regs, regs->nip);
        if (pfn != ULONG_MAX) {
                instr_addr = (pfn << PAGE_SHIFT) + (regs->nip & ~PAGE_MASK);
-               instr = *(struct ppc_inst *)(instr_addr);
+               instr = ppc_inst_read((struct ppc_inst *)instr_addr);
                if (!analyse_instr(&op, &tmp, instr)) {
                        pfn = addr_to_pfn(regs, op.ea);
                        *addr = op.ea;

diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
index 5a71fef..52c1ab3 100644 (file)
--- a/arch/powerpc/kernel/optprobes.c
+++ b/arch/powerpc/kernel/optprobes.c
@@ -100,9 +100,9 @@ static unsigned long can_optimize(struct kprobe *p)
         * Ensure that the instruction is not a conditional branch,
         * and that can be emulated.
         */
-       if (!is_conditional_branch(*(struct ppc_inst *)p->ainsn.insn) &&
+       if (!is_conditional_branch(ppc_inst_read((struct ppc_inst *)p->ainsn.insn)) &&
            analyse_instr(&op, &regs,
-                         *(struct ppc_inst *)p->ainsn.insn) == 1) {
+                         ppc_inst_read((struct ppc_inst *)p->ainsn.insn)) == 1) {
                emulate_update_regs(&regs, &op);
                nip = regs.nip;
        }

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 3117ed6..acd5b88 100644 (file)
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -848,7 +848,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
        struct ppc_inst old, new;
        int ret;
 
-       old = *(struct ppc_inst *)&ftrace_call;
+       old = ppc_inst_read((struct ppc_inst *)&ftrace_call);
        new = ftrace_call_replace(ip, (unsigned long)func, 1);
        ret = ftrace_modify_code(ip, old, new);
 
@@ -856,7 +856,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
        /* Also update the regs callback function */
        if (!ret) {
                ip = (unsigned long)(&ftrace_regs_call);
-               old = *(struct ppc_inst *)&ftrace_regs_call;
+               old = ppc_inst_read((struct ppc_inst *)&ftrace_regs_call);
                new = ftrace_call_replace(ip, (unsigned long)func, 1);
                ret = ftrace_modify_code(ip, old, new);
        }

diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c
index 31c8702..6893d40 100644 (file)
--- a/arch/powerpc/kernel/uprobes.c
+++ b/arch/powerpc/kernel/uprobes.c
@@ -174,7 +174,7 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
         * emulate_step() returns 1 if the insn was successfully emulated.
         * For all other cases, we need to single-step in hardware.
         */
-       ret = emulate_step(regs, auprobe->insn);
+       ret = emulate_step(regs, ppc_inst_read(&auprobe->insn));
        if (ret > 0)
                return true;
 

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 1dff9d9..435fc8e 100644 (file)
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -348,9 +348,9 @@ static unsigned long branch_bform_target(const struct ppc_inst *instr)
 
 unsigned long branch_target(const struct ppc_inst *instr)
 {
-       if (instr_is_branch_iform(*instr))
+       if (instr_is_branch_iform(ppc_inst_read(instr)))
                return branch_iform_target(instr);
-       else if (instr_is_branch_bform(*instr))
+       else if (instr_is_branch_bform(ppc_inst_read(instr)))
                return branch_bform_target(instr);
 
        return 0;
@@ -358,7 +358,8 @@ unsigned long branch_target(const struct ppc_inst *instr)
 
 int instr_is_branch_to_addr(const struct ppc_inst *instr, unsigned long addr)
 {
-       if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
+       if (instr_is_branch_iform(ppc_inst_read(instr)) ||
+           instr_is_branch_bform(ppc_inst_read(instr)))
                return branch_target(instr) == addr;
 
        return 0;
@@ -368,13 +369,14 @@ int translate_branch(struct ppc_inst *instr, const struct ppc_inst *dest,
                     const struct ppc_inst *src)
 {
        unsigned long target;
-
        target = branch_target(src);
 
-       if (instr_is_branch_iform(*src))
-               return create_branch(instr, dest, target, ppc_inst_val(*src));
-       else if (instr_is_branch_bform(*src))
-               return create_cond_branch(instr, dest, target, ppc_inst_val(*src));
+       if (instr_is_branch_iform(ppc_inst_read(src)))
+               return create_branch(instr, dest, target,
+                                    ppc_inst_val(ppc_inst_read(src)));
+       else if (instr_is_branch_bform(ppc_inst_read(src)))
+               return create_cond_branch(instr, dest, target,
+                                         ppc_inst_val(ppc_inst_read(src)));
 
        return 1;
 }
@@ -598,7 +600,7 @@ static void __init test_translate_branch(void)
        patch_instruction(q, instr);
        check(instr_is_branch_to_addr(p, addr));
        check(instr_is_branch_to_addr(q, addr));
-       check(ppc_inst_equal(*q, ppc_inst(0x4a000000)));
+       check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
 
        /* Maximum positive case, move x to x - 32 MB + 4 */
        p = buf + 0x2000000;
@@ -609,7 +611,7 @@ static void __init test_translate_branch(void)
        patch_instruction(q, instr);
        check(instr_is_branch_to_addr(p, addr));
        check(instr_is_branch_to_addr(q, addr));
-       check(ppc_inst_equal(*q, ppc_inst(0x49fffffc)));
+       check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
 
        /* Jump to x + 16 MB moved to x + 20 MB */
        p = buf;
@@ -655,7 +657,7 @@ static void __init test_translate_branch(void)
        patch_instruction(q, instr);
        check(instr_is_branch_to_addr(p, addr));
        check(instr_is_branch_to_addr(q, addr));
-       check(ppc_inst_equal(*q, ppc_inst(0x43ff8000)));
+       check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
 
        /* Maximum positive case, move x to x - 32 KB + 4 */
        p = buf + 0x8000;
@@ -667,7 +669,7 @@ static void __init test_translate_branch(void)
        patch_instruction(q, instr);
        check(instr_is_branch_to_addr(p, addr));
        check(instr_is_branch_to_addr(q, addr));
-       check(ppc_inst_equal(*q, ppc_inst(0x43ff7ffc)));
+       check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
 
        /* Jump to x + 12 KB moved to x + 20 KB */
        p = buf;

diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index fd978b8..3c55097 100644 (file)
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -48,7 +48,7 @@ static int patch_alt_instruction(struct ppc_inst *src, struct ppc_inst *dest,
        int err;
        struct ppc_inst instr;
 
-       instr = *src;
+       instr = ppc_inst_read(src);
 
        if (instr_is_relative_branch(*src)) {
                struct ppc_inst *target = (struct ppc_inst *)branch_target(src);
@@ -403,7 +403,7 @@ static void do_final_fixups(void)
        length = (__end_interrupts - _stext) / sizeof(struct ppc_inst);
 
        while (length--) {
-               raw_patch_instruction(dest, *src);
+               raw_patch_instruction(dest, ppc_inst_read(src));
                src++;
                dest++;
        }

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 2e3b158..a4f8f57 100644 (file)
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -702,13 +702,13 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
        if ((regs->msr & (MSR_IR|MSR_PR|MSR_64BIT)) == (MSR_IR|MSR_64BIT)) {
                bp = at_breakpoint(regs->nip);
                if (bp != NULL) {
-                       int stepped = emulate_step(regs, bp->instr[0]);
+                       int stepped = emulate_step(regs, ppc_inst_read(bp->instr));
                        if (stepped == 0) {
                                regs->nip = (unsigned long) &bp->instr[0];
                                atomic_inc(&bp->ref_count);
                        } else if (stepped < 0) {
                                printf("Couldn't single-step %s instruction\n",
-                                   (IS_RFID(bp->instr[0])? "rfid": "mtmsrd"));
+                                   IS_RFID(ppc_inst_read(bp->instr))? "rfid": "mtmsrd");
                        }
                }
        }
@@ -949,7 +949,7 @@ static void remove_bpts(void)
                if (mread(bp->address, &instr, 4) == 4
                    && ppc_inst_equal(instr, ppc_inst(bpinstr))
                    && patch_instruction(
-                       (struct ppc_inst *)bp->address, bp->instr[0]) != 0)
+                       (struct ppc_inst *)bp->address, ppc_inst_read(bp->instr)) != 0)
                        printf("Couldn't remove breakpoint at %lx\n",
                               bp->address);
        }