diff options
| author | Masami Hiramatsu <mhiramat@kernel.org> | 2017-01-08 23:58:09 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-01-14 08:38:05 +0100 |
| commit | 5b485629ba0d5d027880769ff467c587b24b4bde (patch) | |
| tree | 395ec5583989fd297007dfd2c7d04292ed273242 /kernel/extable.c | |
| parent | f913f3a655cb4c37129bb36c9f175071e1fbdc29 (diff) | |
kprobes, extable: Identify kprobes trampolines as kernel text area
Improve __kernel_text_address()/kernel_text_address() to return
true if the given address is on a kprobe's instruction slot
trampoline.
This can help stacktraces to determine the address is on a
text area or not.
To implement this atomically in is_kprobe_*_slot(), also change
the insn_cache page list to an RCU list.
This changes timings a bit (it delays page freeing to the RCU garbage
collection phase), but none of that is in the hot path.
Note: this change can add small overhead to stack unwinders because
it adds 2 additional checks to __kernel_text_address(). However, the
impact should be very small, because kprobe_insn_pages list has 1 entry
per 256 probes(on x86, on arm/arm64 it will be 1024 probes),
and kprobe_optinsn_pages has 1 entry per 32 probes(on x86).
In most use cases, the number of kprobe events may be less
than 20, which means that is_kprobe_*_slot() will check just one entry.
Tested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/148388747896.6869.6354262871751682264.stgit@devbox
[ Improved the changelog and coding style. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/extable.c')
| -rw-r--r-- | kernel/extable.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/kernel/extable.c b/kernel/extable.c index e3beec4a2339..e1359474baa5 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -20,6 +20,7 @@ #include <linux/module.h> #include <linux/mutex.h> #include <linux/init.h> +#include <linux/kprobes.h> #include <asm/sections.h> #include <linux/uaccess.h> @@ -104,6 +105,8 @@ int __kernel_text_address(unsigned long addr) return 1; if (is_ftrace_trampoline(addr)) return 1; + if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr)) + return 1; /* * There might be init symbols in saved stacktraces. * Give those symbols a chance to be printed in @@ -123,7 +126,11 @@ int kernel_text_address(unsigned long addr) return 1; if (is_module_text_address(addr)) return 1; - return is_ftrace_trampoline(addr); + if (is_ftrace_trampoline(addr)) + return 1; + if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr)) + return 1; + return 0; } /* |