Re: [RFT PATCH -next v3] [BUGFIX] kprobes: Fix "Failed to find blacklist" error on ia64 and ppc64

Masami Hiramatsu
2014-06-06T06:38:14Z

Ping?

I guess this should go to 3.16 branch, shouldn't it?

(2014/05/30 12:18), Masami Hiramatsu wrote:
> On ia64 and ppc64, the function pointer does not point the
> entry address of the function, but the address of function
> discriptor (which contains the entry address and misc
> data.) Since the kprobes passes the function pointer stored
> by NOKPROBE_SYMBOL() to kallsyms_lookup_size_offset() for
> initalizing its blacklist, it fails and reports many errors
> as below.
>
> Failed to find blacklist 0001013168300000
> Failed to find blacklist 0001013000f0a000
> Failed to find blacklist 000101315f70a000
> Failed to find blacklist 000101324c80a000
> Failed to find blacklist 0001013063f0a000
> Failed to find blacklist 000101327800a000
> Failed to find blacklist 0001013277f0a000
> Failed to find blacklist 000101315a70a000
> Failed to find blacklist 0001013277e0a000
> Failed to find blacklist 000101305a20a000
> Failed to find blacklist 0001013277d0a000
> Failed to find blacklist 00010130bdc0a000
> Failed to find blacklist 00010130dc20a000
> Failed to find blacklist 000101309a00a000
> Failed to find blacklist 0001013277c0a000
> Failed to find blacklist 0001013277b0a000
> Failed to find blacklist 0001013277a0a000
> Failed to find blacklist 000101327790a000
> Failed to find blacklist 000101303140a000
> Failed to find blacklist 0001013a3280a000
>
> To fix this bug, this introduces function_entry() macro to
> retrieve the entry address from the given function pointer,
> and uses for kallsyms_lookup_size_offset() while initializing
> blacklist.
>
> Changes in v3:
> - Fix a bug to get blacklist address based on function entry
> instead of function descriptor. (Suzuki's work, Thanks!)
>
> Changes in V2:
> - Use function_entry() macro when lookin up symbols instead
> of storing it.
> - Update for the latest -next.
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
> Reported-by: Tony Luck <tony.luck@gmail.com>
> Cc: Suzuki K. Poulose <suzuki@in.ibm.com>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Kevin Hao <haokexin@gmail.com>
> Cc: linux-ia64@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> ---
> arch/ia64/include/asm/types.h | 2 ++
> arch/powerpc/include/asm/types.h | 11 +++++++++++
> include/linux/types.h | 4 ++++
> kernel/kprobes.c | 11 +++++++----
> 4 files changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/arch/ia64/include/asm/types.h b/arch/ia64/include/asm/types.h
> index 4c351b1..95279dd 100644
> --- a/arch/ia64/include/asm/types.h
> +++ b/arch/ia64/include/asm/types.h
> @@ -27,5 +27,7 @@ struct fnptr {
> unsigned long gp;
> };
>
> +#define function_entry(fn) (((struct fnptr *)(fn))->ip)
> +
> #endif /* !__ASSEMBLY__ */
> #endif /* _ASM_IA64_TYPES_H */
> diff --git a/arch/powerpc/include/asm/types.h b/arch/powerpc/include/asm/types.h
> index bfb6ded..8b89d65 100644
> --- a/arch/powerpc/include/asm/types.h
> +++ b/arch/powerpc/include/asm/types.h
> @@ -25,6 +25,17 @@ typedef struct {
> unsigned long env;
> } func_descr_t;
>
> +#if defined(CONFIG_PPC64) && (!defined(_CALL_ELF) || _CALL_ELF = 1)
> +/*
> + * On PPC64 ABIv1 the function pointer actually points to the
> + * function's descriptor. The first entry in the descriptor is the
> + * address of the function text.
> + */
> +#define function_entry(fn) (((func_descr_t *)(fn))->entry)
> +#else
> +#define function_entry(fn) ((unsigned long)(fn))
> +#endif
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_POWERPC_TYPES_H */
> diff --git a/include/linux/types.h b/include/linux/types.h
> index a0bb704..3b95369 100644
> --- a/include/linux/types.h
> +++ b/include/linux/types.h
> @@ -213,5 +213,9 @@ struct callback_head {
> };
> #define rcu_head callback_head
>
> +#ifndef function_entry
> +#define function_entry(fn) ((unsigned long)(fn))
> +#endif
> +
> #endif /* __ASSEMBLY__ */
> #endif /* _LINUX_TYPES_H */
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 2ac9f13..3f2d6d4 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -32,6 +32,7 @@
> * <prasanna@in.ibm.com> added function-return probes.
> */
> #include <linux/kprobes.h>
> +#include <linux/types.h>
> #include <linux/hash.h>
> #include <linux/init.h>
> #include <linux/slab.h>
> @@ -2042,16 +2043,18 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
> unsigned long offset = 0, size = 0;
>
> for (iter = start; iter < end; iter++) {
> - if (!kallsyms_lookup_size_offset(*iter, &size, &offset)) {
> - pr_err("Failed to find blacklist %p\n", (void *)*iter);
> + unsigned long entry = function_entry(*iter);
> + if (!kallsyms_lookup_size_offset(entry, &size, &offset)) {
> + pr_err("Failed to find blacklist at %p\n",
> + (void *)entry);
> continue;
> }
>
> ent = kmalloc(sizeof(*ent), GFP_KERNEL);
> if (!ent)
> return -ENOMEM;
> - ent->start_addr = *iter;
> - ent->end_addr = *iter + size;
> + ent->start_addr = entry;
> + ent->end_addr = entry + size;
> INIT_LIST_HEAD(&ent->list);
> list_add_tail(&ent->list, &kprobe_blacklist);
> }