Re: [RFC PATCH 2/2] kprobes: Allow specifying names for certain blacklisted address ranges

[Masami Hiramatsu]

On Thu, 29 Jun 2017 19:38:38 +0530
"Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxxxxxxx> wrote:

> This allows us to provide meaningful names for certain address ranges
> that are blacklisted such as those with __kprobes annotation, kernel
> entry text, and so on. For such ranges, using the symbol/function name
> at the start of the range is misleading.
> 
> On a powerpc64le system, before patch:
>   root@ubuntu:/sys/kernel/debug# tail kprobes/blacklist
>   0xc00000000022d500-0xc00000000022d580	print_type_s64
>   0xc00000000022d480-0xc00000000022d500	print_type_s32
>   0xc00000000022d400-0xc00000000022d480	print_type_s16
>   0xc00000000022d380-0xc00000000022d400	print_type_s8
>   0xc00000000022d300-0xc00000000022d380	print_type_u64
>   0xc00000000022d280-0xc00000000022d300	print_type_u32
>   0xc00000000022d200-0xc00000000022d280	print_type_u16
>   0xc00000000022d180-0xc00000000022d200	print_type_u8
>   0xc0000000009ed778-0xc0000000009ed778	__irqentry_text_end
>   0xc000000000000000-0xc000000000008000	start_first_256B
> 
> After patch:
>   root@ubuntu:/sys/kernel/debug# tail kprobes/blacklist
>   0xc00000000022d540-0xc00000000022d5c0	print_type_s64
>   0xc00000000022d4c0-0xc00000000022d540	print_type_s32
>   0xc00000000022d440-0xc00000000022d4c0	print_type_s16
>   0xc00000000022d3c0-0xc00000000022d440	print_type_s8
>   0xc00000000022d340-0xc00000000022d3c0	print_type_u64
>   0xc00000000022d2c0-0xc00000000022d340	print_type_u32
>   0xc00000000022d240-0xc00000000022d2c0	print_type_u16
>   0xc00000000022d1c0-0xc00000000022d240	print_type_u8
>   0xc0000000009ed7b8-0xc0000000009ed7b8	[__kprobes]
>   0xc000000000000000-0xc000000000008000	[__exceptions]

Looks good to me :)

Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

Thanks!

> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
> ---
>  arch/arm64/kernel/probes/kprobes.c | 10 +++++-----
>  arch/powerpc/kernel/kprobes.c      |  4 ++--
>  arch/x86/kernel/kprobes/core.c     |  4 ++--
>  include/linux/kprobes.h            |  3 ++-
>  kernel/kprobes.c                   | 17 ++++++++++++-----
>  5 files changed, 23 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> index 7f453a71b5a8..340325ec97c6 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -544,17 +544,17 @@ bool arch_within_kprobe_blacklist(unsigned long addr)
>  void __init arch_populate_kprobe_blacklist(void)
>  {
>  	insert_kprobe_blacklist((unsigned long)__kprobes_text_start,
> -				(unsigned long)__kprobes_text_end);
> +				(unsigned long)__kprobes_text_end, "[__kprobes]");
>  	insert_kprobe_blacklist((unsigned long)__entry_text_start,
> -				(unsigned long)__entry_text_end);
> +				(unsigned long)__entry_text_end, "[__entry]");
>  	insert_kprobe_blacklist((unsigned long)__idmap_text_start,
> -				(unsigned long)__idmap_text_end);
> +				(unsigned long)__idmap_text_end, "[__idmap]");
>  
>  	if (!is_kernel_in_hyp_mode()) {
>  		insert_kprobe_blacklist((unsigned long)__hyp_text_start,
> -					(unsigned long)__hyp_text_end);
> +					(unsigned long)__hyp_text_end, "[__hyp]");
>  		insert_kprobe_blacklist((unsigned long)__hyp_idmap_text_start,
> -					(unsigned long)__hyp_idmap_text_end);
> +					(unsigned long)__hyp_idmap_text_end, "[__hyp_idmap]");
>  	}
>  }
>  
> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
> index f707e42b3482..1b873e19d29b 100644
> --- a/arch/powerpc/kernel/kprobes.c
> +++ b/arch/powerpc/kernel/kprobes.c
> @@ -52,9 +52,9 @@ int is_current_kprobe_addr(unsigned long addr)
>  void __init arch_populate_kprobe_blacklist(void)
>  {
>  	insert_kprobe_blacklist((unsigned long)__kprobes_text_start,
> -				(unsigned long)__kprobes_text_end);
> +				(unsigned long)__kprobes_text_end, "[__kprobes]");
>  	insert_kprobe_blacklist((unsigned long)_stext,
> -				(unsigned long)__head_end);
> +				(unsigned long)__head_end, "[__exceptions]");
>  }
>  
>  kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
> diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
> index 4a5fc04b3e92..20e71d783bcf 100644
> --- a/arch/x86/kernel/kprobes/core.c
> +++ b/arch/x86/kernel/kprobes/core.c
> @@ -1144,9 +1144,9 @@ NOKPROBE_SYMBOL(longjmp_break_handler);
>  void __init arch_populate_kprobe_blacklist(void)
>  {
>  	insert_kprobe_blacklist((unsigned long)__kprobes_text_start,
> -				(unsigned long)__kprobes_text_end);
> +				(unsigned long)__kprobes_text_end, "[__kprobes]");
>  	insert_kprobe_blacklist((unsigned long)__entry_text_start,
> -				(unsigned long)__entry_text_end);
> +				(unsigned long)__entry_text_end, "[__entry]");
>  }
>  
>  int __init arch_init_kprobes(void)
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index 6d931ea0604e..05a4f2619cdc 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -210,6 +210,7 @@ struct kprobe_blacklist_entry {
>  	struct list_head list;
>  	unsigned long start_addr;
>  	unsigned long end_addr;
> +	char *name;
>  };
>  
>  #ifdef CONFIG_KPROBES
> @@ -271,7 +272,7 @@ extern bool arch_function_offset_within_entry(unsigned long offset);
>  extern bool function_offset_within_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
>  
>  extern bool within_kprobe_blacklist(unsigned long addr);
> -extern void insert_kprobe_blacklist(unsigned long start, unsigned long end);
> +extern void insert_kprobe_blacklist(unsigned long start, unsigned long end, const char *name);
>  extern void arch_populate_kprobe_blacklist(void);
>  
>  struct kprobe_insn_cache {
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 8ddbee01ce01..fcb1765de49e 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2125,7 +2125,8 @@ NOKPROBE_SYMBOL(dump_kprobe);
>  extern unsigned long __start_kprobe_blacklist[];
>  extern unsigned long __stop_kprobe_blacklist[];
>  
> -void __init insert_kprobe_blacklist(unsigned long start, unsigned long end)
> +void __init insert_kprobe_blacklist(unsigned long start, unsigned long end,
> +						const char *name)
>  {
>  	struct kprobe_blacklist_entry *ent;
>  
> @@ -2137,6 +2138,7 @@ void __init insert_kprobe_blacklist(unsigned long start, unsigned long end)
>  
>  	ent->start_addr = start;
>  	ent->end_addr = end;
> +	ent->name = kstrdup(name, GFP_KERNEL);
>  	INIT_LIST_HEAD(&ent->list);
>  	list_add_tail(&ent->list, &kprobe_blacklist);
>  }
> @@ -2145,7 +2147,7 @@ void __weak __init arch_populate_kprobe_blacklist(void)
>  {
>  	/* The __kprobes marked functions and entry code must not be probed */
>  	insert_kprobe_blacklist((unsigned long)__kprobes_text_start,
> -				(unsigned long)__kprobes_text_end);
> +				(unsigned long)__kprobes_text_end, "[__kprobes]");
>  }
>  
>  static void __init populate_kprobe_blacklist(void)
> @@ -2165,7 +2167,7 @@ static void __init populate_kprobe_blacklist(void)
>  			continue;
>  		}
>  
> -		insert_kprobe_blacklist(entry, entry + size);
> +		insert_kprobe_blacklist(entry, entry + size, NULL);
>  	}
>  
>  	/* Let architectures add their own entries as well */
> @@ -2378,8 +2380,13 @@ static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
>  	struct kprobe_blacklist_entry *ent =
>  		list_entry(v, struct kprobe_blacklist_entry, list);
>  
> -	seq_printf(m, "0x%p-0x%p\t%ps\n", (void *)ent->start_addr,
> -		   (void *)ent->end_addr, (void *)ent->start_addr);
> +	if (ent->name)
> +		seq_printf(m, "0x%p-0x%p\t%s\n", (void *)ent->start_addr,
> +			   (void *)ent->end_addr, ent->name);
> +	else
> +		seq_printf(m, "0x%p-0x%p\t%ps\n", (void *)ent->start_addr,
> +			   (void *)ent->end_addr, (void *)ent->start_addr);
> +
>  	return 0;
>  }
>  
> -- 
> 2.13.1
> 


-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>