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perf/x86/hw_breakpoints: Improve range breakpoint validation

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Range breakpoints will do the wrong thing if the address isn't
aligned.  While we're there, add comments about why it's safe for
instruction breakpoints.

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/ae25d14d61f2f43b78e0a247e469f3072df7e201.1438312874.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2015-07-30 20:32:41 -07:00 committed by Ingo Molnar
parent e5779e8e12
commit ab513927ab
1 changed files with 10 additions and 0 deletions
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10
arch/x86/kernel/hw_breakpoint.c
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@ -291,8 +291,18 @@ static int arch_build_bp_info(struct perf_event *bp)
break; break;
#endif #endif
default: default:
/* AMD range breakpoint */
if (!is_power_of_2(bp->attr.bp_len)) if (!is_power_of_2(bp->attr.bp_len))
return -EINVAL; return -EINVAL;
if (bp->attr.bp_addr & (bp->attr.bp_len - 1))
return -EINVAL;
/*
* It's impossible to use a range breakpoint to fake out
* user vs kernel detection because bp_len - 1 can't
* have the high bit set. If we ever allow range instruction
* breakpoints, then we'll have to check for kprobe-blacklisted
* addresses anywhere in the range.
*/
if (!cpu_has_bpext) if (!cpu_has_bpext)
return -EOPNOTSUPP; return -EOPNOTSUPP;
info->mask = bp->attr.bp_len - 1; info->mask = bp->attr.bp_len - 1;