lkml.org 
[lkml]   [2010]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH 09/11] jump label: jump_label_text_reserved() to reserve our jump points
    Add a jump_label_text_reserved(void *start, void *end), so that other
    pieces of code that want to modify kernel text, can first verify that
    jump label has not reserved the instruction.

    Signed-off-by: Jason Baron <jbaron@redhat.com>
    Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
    ---
    arch/x86/kernel/kprobes.c | 3 +-
    include/linux/jump_label.h | 6 +++
    kernel/jump_label.c | 83 ++++++++++++++++++++++++++++++++++++++++++++
    kernel/kprobes.c | 3 +-
    4 files changed, 93 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
    index f2f56c0..7a7343b 100644
    --- a/arch/x86/kernel/kprobes.c
    +++ b/arch/x86/kernel/kprobes.c
    @@ -1202,7 +1202,8 @@ static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src)
    }
    /* Check whether the address range is reserved */
    if (ftrace_text_reserved(src, src + len - 1) ||
    - alternatives_text_reserved(src, src + len - 1))
    + alternatives_text_reserved(src, src + len - 1) ||
    + jump_label_text_reserved(src, src + len - 1))
    return -EBUSY;

    return len;
    diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
    index 7de278d..2464348 100644
    --- a/include/linux/jump_label.h
    +++ b/include/linux/jump_label.h
    @@ -30,6 +30,7 @@ extern void arch_jump_label_transform(struct jump_entry *entry,
    extern const u8 *arch_get_jump_label_nop(void);

    extern void jump_label_update(const char *name, enum jump_label_type type);
    +extern int jump_label_text_reserved(void *start, void *end);

    extern void apply_jump_label_nops(struct module *mod);

    @@ -64,6 +65,11 @@ static inline int apply_jump_label_nops(struct module *mod)
    return 0;
    }

    +static inline int jump_label_text_reserved(void *start, void *end)
    +{
    + return 0;
    +}
    +
    #endif

    #endif
    diff --git a/kernel/jump_label.c b/kernel/jump_label.c
    index 1db7a63..f44c792 100644
    --- a/kernel/jump_label.c
    +++ b/kernel/jump_label.c
    @@ -182,6 +182,89 @@ void jump_label_update(const char *name, enum jump_label_type type)
    mutex_unlock(&jump_label_mutex);
    }

    +static int addr_conflict(struct jump_entry *entry, void *start, void *end)
    +{
    + if (entry->code <= (unsigned long)end &&
    + entry->code + IDEAL_NOP_SIZE_5 > (unsigned long)start)
    + return 1;
    +
    + return 0;
    +}
    +
    +#ifdef CONFIG_MODULES
    +
    +static int module_conflict(void *start, void *end)
    +{
    + struct hlist_head *head;
    + struct hlist_node *node, *node_next, *module_node, *module_node_next;
    + struct jump_label_entry *e;
    + struct jump_label_module_entry *e_module;
    + struct jump_entry *iter;
    + int i, count;
    + int conflict = 0;
    +
    + for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
    + head = &jump_label_table[i];
    + hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
    + hlist_for_each_entry_safe(e_module, module_node,
    + module_node_next,
    + &(e->modules), hlist) {
    + count = e_module->nr_entries;
    + iter = e_module->table;
    + while (count--) {
    + if (addr_conflict(iter, start, end)) {
    + conflict = 1;
    + goto out;
    + }
    + iter++;
    + }
    + }
    + }
    + }
    +out:
    + return conflict;
    +}
    +
    +#endif
    +
    +/***
    + * jump_label_text_reserved - check if addr range is reserved
    + * @start: start text addr
    + * @end: end text addr
    + *
    + * checks if the text addr located between @start and @end
    + * overlaps with any of the jump label patch addresses. Code
    + * that wants to modify kernel text should first verify that
    + * it does not overlap with any of the jump label addresses.
    + *
    + * returns 1 if there is an overlap, 0 otherwise
    + */
    +int jump_label_text_reserved(void *start, void *end)
    +{
    + struct jump_entry *iter;
    + struct jump_entry *iter_start = __start___jump_table;
    + struct jump_entry *iter_stop = __start___jump_table;
    + int conflict = 0;
    +
    + mutex_lock(&jump_label_mutex);
    + iter = iter_start;
    + while (iter < iter_stop) {
    + if (addr_conflict(iter, start, end)) {
    + conflict = 1;
    + goto out;
    + }
    + iter++;
    + }
    +
    + /* now check modules */
    +#ifdef CONFIG_MODULES
    + conflict = module_conflict(start, end);
    +#endif
    +out:
    + mutex_unlock(&jump_label_mutex);
    + return conflict;
    +}
    +
    static int init_jump_label(void)
    {
    int ret;
    diff --git a/kernel/kprobes.c b/kernel/kprobes.c
    index 0ed46f3..e866e04 100644
    --- a/kernel/kprobes.c
    +++ b/kernel/kprobes.c
    @@ -1141,7 +1141,8 @@ int __kprobes register_kprobe(struct kprobe *p)
    preempt_disable();
    if (!kernel_text_address((unsigned long) p->addr) ||
    in_kprobes_functions((unsigned long) p->addr) ||
    - ftrace_text_reserved(p->addr, p->addr)) {
    + ftrace_text_reserved(p->addr, p->addr) ||
    + jump_label_text_reserved(p->addr, p->addr)) {
    preempt_enable();
    return -EINVAL;
    }
    --
    1.7.0.1


    \
     
     \ /
      Last update: 2010-04-16 17:29    [W:0.030 / U:0.208 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site