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    Subject[PATCH v3 1/7] kprobes: convert kprobe_lookup_name() to a function
    Date
    The macro is now pretty long and ugly on powerpc. In the light of
    further changes needed here, convert it to a __weak variant to be
    over-ridden with a nicer looking function.

    Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
    Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
    Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
    ---
    arch/powerpc/include/asm/kprobes.h | 53 ----------------------------------
    arch/powerpc/kernel/kprobes.c | 58 ++++++++++++++++++++++++++++++++++++++
    arch/powerpc/kernel/optprobes.c | 4 +--
    include/linux/kprobes.h | 1 +
    kernel/kprobes.c | 20 ++++++-------
    5 files changed, 69 insertions(+), 67 deletions(-)

    diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h
    index 0503c98b2117..a843884aafaf 100644
    --- a/arch/powerpc/include/asm/kprobes.h
    +++ b/arch/powerpc/include/asm/kprobes.h
    @@ -61,59 +61,6 @@ extern kprobe_opcode_t optprobe_template_end[];
    #define MAX_OPTINSN_SIZE (optprobe_template_end - optprobe_template_entry)
    #define RELATIVEJUMP_SIZE sizeof(kprobe_opcode_t) /* 4 bytes */

    -#ifdef PPC64_ELF_ABI_v2
    -/* PPC64 ABIv2 needs local entry point */
    -#define kprobe_lookup_name(name, addr) \
    -{ \
    - addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); \
    - if (addr) \
    - addr = (kprobe_opcode_t *)ppc_function_entry(addr); \
    -}
    -#elif defined(PPC64_ELF_ABI_v1)
    -/*
    - * 64bit powerpc ABIv1 uses function descriptors:
    - * - Check for the dot variant of the symbol first.
    - * - If that fails, try looking up the symbol provided.
    - *
    - * This ensures we always get to the actual symbol and not the descriptor.
    - * Also handle <module:symbol> format.
    - */
    -#define kprobe_lookup_name(name, addr) \
    -{ \
    - char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN]; \
    - const char *modsym; \
    - bool dot_appended = false; \
    - if ((modsym = strchr(name, ':')) != NULL) { \
    - modsym++; \
    - if (*modsym != '\0' && *modsym != '.') { \
    - /* Convert to <module:.symbol> */ \
    - strncpy(dot_name, name, modsym - name); \
    - dot_name[modsym - name] = '.'; \
    - dot_name[modsym - name + 1] = '\0'; \
    - strncat(dot_name, modsym, \
    - sizeof(dot_name) - (modsym - name) - 2);\
    - dot_appended = true; \
    - } else { \
    - dot_name[0] = '\0'; \
    - strncat(dot_name, name, sizeof(dot_name) - 1); \
    - } \
    - } else if (name[0] != '.') { \
    - dot_name[0] = '.'; \
    - dot_name[1] = '\0'; \
    - strncat(dot_name, name, KSYM_NAME_LEN - 2); \
    - dot_appended = true; \
    - } else { \
    - dot_name[0] = '\0'; \
    - strncat(dot_name, name, KSYM_NAME_LEN - 1); \
    - } \
    - addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name); \
    - if (!addr && dot_appended) { \
    - /* Let's try the original non-dot symbol lookup */ \
    - addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); \
    - } \
    -}
    -#endif
    -
    #define flush_insn_slot(p) do { } while (0)
    #define kretprobe_blacklist_size 0

    diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
    index 331751701fed..71c30025cc8a 100644
    --- a/arch/powerpc/kernel/kprobes.c
    +++ b/arch/powerpc/kernel/kprobes.c
    @@ -42,6 +42,64 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);

    struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};

    +kprobe_opcode_t *kprobe_lookup_name(const char *name)
    +{
    + kprobe_opcode_t *addr;
    +
    +#ifdef PPC64_ELF_ABI_v2
    + /* PPC64 ABIv2 needs local entry point */
    + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
    + if (addr)
    + addr = (kprobe_opcode_t *)ppc_function_entry(addr);
    +#elif defined(PPC64_ELF_ABI_v1)
    + /*
    + * 64bit powerpc ABIv1 uses function descriptors:
    + * - Check for the dot variant of the symbol first.
    + * - If that fails, try looking up the symbol provided.
    + *
    + * This ensures we always get to the actual symbol and not
    + * the descriptor.
    + *
    + * Also handle <module:symbol> format.
    + */
    + char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN];
    + const char *modsym;
    + bool dot_appended = false;
    + if ((modsym = strchr(name, ':')) != NULL) {
    + modsym++;
    + if (*modsym != '\0' && *modsym != '.') {
    + /* Convert to <module:.symbol> */
    + strncpy(dot_name, name, modsym - name);
    + dot_name[modsym - name] = '.';
    + dot_name[modsym - name + 1] = '\0';
    + strncat(dot_name, modsym,
    + sizeof(dot_name) - (modsym - name) - 2);
    + dot_appended = true;
    + } else {
    + dot_name[0] = '\0';
    + strncat(dot_name, name, sizeof(dot_name) - 1);
    + }
    + } else if (name[0] != '.') {
    + dot_name[0] = '.';
    + dot_name[1] = '\0';
    + strncat(dot_name, name, KSYM_NAME_LEN - 2);
    + dot_appended = true;
    + } else {
    + dot_name[0] = '\0';
    + strncat(dot_name, name, KSYM_NAME_LEN - 1);
    + }
    + addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name);
    + if (!addr && dot_appended) {
    + /* Let's try the original non-dot symbol lookup */
    + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
    + }
    +#else
    + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
    +#endif
    +
    + return addr;
    +}
    +
    int __kprobes arch_prepare_kprobe(struct kprobe *p)
    {
    int ret = 0;
    diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
    index 2282bf4e63cd..aefe076d00e0 100644
    --- a/arch/powerpc/kernel/optprobes.c
    +++ b/arch/powerpc/kernel/optprobes.c
    @@ -243,8 +243,8 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
    /*
    * 2. branch to optimized_callback() and emulate_step()
    */
    - kprobe_lookup_name("optimized_callback", op_callback_addr);
    - kprobe_lookup_name("emulate_step", emulate_step_addr);
    + op_callback_addr = kprobe_lookup_name("optimized_callback");
    + emulate_step_addr = kprobe_lookup_name("emulate_step");
    if (!op_callback_addr || !emulate_step_addr) {
    WARN(1, "kprobe_lookup_name() failed\n");
    goto error;
    diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
    index c328e4f7dcad..16f153c84646 100644
    --- a/include/linux/kprobes.h
    +++ b/include/linux/kprobes.h
    @@ -379,6 +379,7 @@ static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
    return this_cpu_ptr(&kprobe_ctlblk);
    }

    +kprobe_opcode_t *kprobe_lookup_name(const char *name);
    int register_kprobe(struct kprobe *p);
    void unregister_kprobe(struct kprobe *p);
    int register_kprobes(struct kprobe **kps, int num);
    diff --git a/kernel/kprobes.c b/kernel/kprobes.c
    index 699c5bc51a92..f3421b6b47a3 100644
    --- a/kernel/kprobes.c
    +++ b/kernel/kprobes.c
    @@ -58,15 +58,6 @@
    #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)


    -/*
    - * Some oddball architectures like 64bit powerpc have function descriptors
    - * so this must be overridable.
    - */
    -#ifndef kprobe_lookup_name
    -#define kprobe_lookup_name(name, addr) \
    - addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
    -#endif
    -
    static int kprobes_initialized;
    static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
    static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
    @@ -81,6 +72,11 @@ static struct {
    raw_spinlock_t lock ____cacheline_aligned_in_smp;
    } kretprobe_table_locks[KPROBE_TABLE_SIZE];

    +kprobe_opcode_t * __weak kprobe_lookup_name(const char *name)
    +{
    + return ((kprobe_opcode_t *)(kallsyms_lookup_name(name)));
    +}
    +
    static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
    {
    return &(kretprobe_table_locks[hash].lock);
    @@ -1400,7 +1396,7 @@ static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
    goto invalid;

    if (p->symbol_name) {
    - kprobe_lookup_name(p->symbol_name, addr);
    + addr = kprobe_lookup_name(p->symbol_name);
    if (!addr)
    return ERR_PTR(-ENOENT);
    }
    @@ -2192,8 +2188,8 @@ static int __init init_kprobes(void)
    if (kretprobe_blacklist_size) {
    /* lookup the function address from its name */
    for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
    - kprobe_lookup_name(kretprobe_blacklist[i].name,
    - kretprobe_blacklist[i].addr);
    + kretprobe_blacklist[i].addr =
    + kprobe_lookup_name(kretprobe_blacklist[i].name);
    if (!kretprobe_blacklist[i].addr)
    printk("kretprobe: lookup failed: %s\n",
    kretprobe_blacklist[i].name);
    --
    2.12.1
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