Messages in this thread Patch in this message | | | Date | Fri, 29 Jan 2010 09:25:59 GMT | From | "tip-bot for K.Prasad" <> | Subject | [tip:perf/core] x86/debug: Clear reserved bits of DR6 in do_debug() |
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Commit-ID: 40f9249a73f6c251adea492b1c3d19d39e2a9bda Gitweb: http://git.kernel.org/tip/40f9249a73f6c251adea492b1c3d19d39e2a9bda Author: K.Prasad <prasad@linux.vnet.ibm.com> AuthorDate: Thu, 28 Jan 2010 16:44:01 +0530 Committer: Frederic Weisbecker <fweisbec@gmail.com> CommitDate: Fri, 29 Jan 2010 02:26:10 +0100
x86/debug: Clear reserved bits of DR6 in do_debug()
Clear the reserved bits from the stored copy of debug status register (DR6). This will help easy bitwise operations such as quick testing of a debug event origin.
Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Roland McGrath <roland@redhat.com> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Ingo Molnar <mingo@elte.hu> LKML-Reference: <20100128111401.GB13935@in.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> --- arch/x86/include/asm/debugreg.h | 3 +++ arch/x86/kernel/traps.c | 3 +++ 2 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 8240f76..b81002f 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -14,6 +14,9 @@ which debugging register was responsible for the trap. The other bits are either reserved or not of interest to us. */ +/* Define reserved bits in DR6 which are always set to 1 */ +#define DR6_RESERVED (0xFFFF0FF0) + #define DR_TRAP0 (0x1) /* db0 */ #define DR_TRAP1 (0x2) /* db1 */ #define DR_TRAP2 (0x4) /* db2 */ diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 3339917..1168e44 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -534,6 +534,9 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) get_debugreg(dr6, 6); + /* Filter out all the reserved bits which are preset to 1 */ + dr6 &= ~DR6_RESERVED; + /* Catch kmemcheck conditions first of all! */ if ((dr6 & DR_STEP) && kmemcheck_trap(regs)) return;
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