Frederic Weisbecker 89e45aac42 x86: Fix instruction breakpoint encoding ... Lengths and types of breakpoints are encoded in a half byte into CPU registers. However when we extract these values and store them, we add a high half byte part to them: 0x40 to the length and 0x80 to the type. When that gets reloaded to the CPU registers, the high part is masked. While making the instruction breakpoints available for perf, I zapped that high part on instruction breakpoint encoding and that broke the arch -> generic translation used by ptrace instruction breakpoints. Writing dr7 to set an inst breakpoint was then failing. There is no apparent reason for these high parts so we could get rid of them altogether. That's an invasive change though so let's do that later and for now fix the problem by restoring that inst breakpoint high part encoding in this sole patch. Reported-by: Kelvie Wong <kelvie@ieee.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: Will Deacon <will.deacon@arm.com>		2010-09-17 03:24:13 +02:00
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asm	x86: Fix instruction breakpoint encoding	2010-09-17 03:24:13 +02:00