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authorAndy Lutomirski <luto@kernel.org>2015-07-30 20:32:42 -0700
committerIngo Molnar <mingo@kernel.org>2015-08-04 10:16:55 +0200
commit27747f8bc355a2808ca9e490ab6866acd85b4c16 (patch)
tree27a6a89c2e8497cdf79e461e1084fb872e62987c /arch
parentab513927ab449af00cc70b0269e15ee80dd537f9 (diff)
perf/x86/hw_breakpoints: Fix check for kernel-space breakpoints
The check looked wrong, although I think it was actually safe. TASK_SIZE is unnecessarily small for compat tasks, and it wasn't possible to make a range breakpoint so large it started in user space and ended in kernel space. Nonetheless, let's fix up the check for the benefit of future readers. A breakpoint is in the kernel if either end is in the kernel. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/136be387950e78f18cea60e9d1bef74465d0ee8f.1438312874.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/hw_breakpoint.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 6f345d302cf6..50a3fad5b89f 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -180,7 +180,11 @@ int arch_check_bp_in_kernelspace(struct perf_event *bp)
va = info->address;
len = bp->attr.bp_len;
- return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+ /*
+ * We don't need to worry about va + len - 1 overflowing:
+ * we already require that va is aligned to a multiple of len.
+ */
+ return (va >= TASK_SIZE_MAX) || ((va + len - 1) >= TASK_SIZE_MAX);
}
int arch_bp_generic_fields(int x86_len, int x86_type,