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authorMasami Hiramatsu <mhiramat@kernel.org>2017-01-08 23:58:09 +0900
committerIngo Molnar <mingo@kernel.org>2017-01-14 08:38:05 +0100
commit5b485629ba0d5d027880769ff467c587b24b4bde (patch)
tree395ec5583989fd297007dfd2c7d04292ed273242 /kernel/extable.c
parentf913f3a655cb4c37129bb36c9f175071e1fbdc29 (diff)
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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.c9
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;
}
/*