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    SubjectRe: [PATCH v2 1/5] kprobes: convert kprobe_lookup_name() to a function
    On Wed, 12 Apr 2017 16:28:24 +0530
    "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:

    > 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.

    Looks good to me.

    Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

    Thanks!

    >
    > Suggested-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..a7aa7394954d 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(dot_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
    >


    --
    Masami Hiramatsu <mhiramat@kernel.org>

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