Le 06/05/2020 à 05:40, Jordan Niethe a écrit :
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.


Shouldn't this function be used in mmu_patch_addis() in mm/nohash/8xx.c ?

Christophe


Reviewed-by: Alistair Popple <alist...@popple.id.au>
Signed-off-by: Jordan Niethe <jniet...@gmail.com>
---
v4: New to series
v5: - Rename read_inst() -> probe_kernel_read_inst()
     - No longer modify uprobe probe type in this patch
v6: - feature-fixups.c: do_final_fixups(): Use here
     - arch_prepare_kprobe(): patch_instruction(): no longer part of this
       patch
     - Move probe_kernel_read_inst() out of this patch
     - Use in uprobes
v8: style
---
  arch/powerpc/include/asm/inst.h    |  5 +++++
  arch/powerpc/kernel/kprobes.c      |  6 +++---
  arch/powerpc/kernel/mce_power.c    |  2 +-
  arch/powerpc/kernel/optprobes.c    |  4 ++--
  arch/powerpc/kernel/trace/ftrace.c |  4 ++--
  arch/powerpc/kernel/uprobes.c      |  2 +-
  arch/powerpc/lib/code-patching.c   | 26 ++++++++++++++------------
  arch/powerpc/lib/feature-fixups.c  |  4 ++--
  arch/powerpc/xmon/xmon.c           |  6 +++---
  9 files changed, 33 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
index 19d8bb7a1c2b..552e953bf04f 100644
--- 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 a08ae5803622..f64312dca84f 100644
--- 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 cd23218c60bb..45c51ba0071b 100644
--- a/arch/powerpc/kernel/mce_power.c
+++ b/arch/powerpc/kernel/mce_power.c
@@ -374,7 +374,7 @@ 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 5a71fef71c22..52c1ab3f85aa 100644
--- 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 3117ed675735..acd5b889815f 100644
--- 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 31c870287f2b..6893d40a48c5 100644
--- 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 1dff9d9d6645..435fc8e9f45d 100644
--- 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 fb6e8e8abf4e..c0d3ed4efb7e 100644
--- 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 e0132d6d24d0..68e0b05d9226 100644
--- 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);
        }

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