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authorChuck Ebbert <76306.1226@compuserve.com>2006-01-05 23:11:29 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-05 20:50:51 -0800
commit9f155b9802bb7049cd0f216c3fe903b58620df11 (patch)
treed83fa1699e8113d83588d38a1c16e68cd3fcf462
parent29552b1462799afbe02af035b243e97579d63350 (diff)
downloadop-kernel-dev-9f155b9802bb7049cd0f216c3fe903b58620df11.zip
op-kernel-dev-9f155b9802bb7049cd0f216c3fe903b58620df11.tar.gz
[PATCH] i386: PTRACE_POKEUSR: allow changing RF bit in EFLAGS register.
Setting RF (resume flag) allows a debugger to resume execution after a code breakpoint without tripping the breakpoint again. It is reset by the CPU after execution of one instruction. Requested by Stephane Eranian: "I am trying to the user HW debug registers on i386 and I am running into a problem with ptrace() not allowing access to EFLAGS_RF for POKEUSER (see FLAG_MASK). [ ... ] It avoids the need to remove the breakpoint, single step, and reinstall. The equivalent functionality exists on IA-64 and is allowed by ptrace()" Cc: Stephane Eranian <eranian@hpl.hp.com> Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/kernel/ptrace.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c
index 5ffbb4b..5c1fb6a 100644
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -32,9 +32,12 @@
* in exit.c or in signal.c.
*/
-/* determines which flags the user has access to. */
-/* 1 = access 0 = no access */
-#define FLAG_MASK 0x00044dd5
+/*
+ * Determines which flags the user has access to [1 = access, 0 = no access].
+ * Prohibits changing ID(21), VIP(20), VIF(19), VM(17), IOPL(12-13), IF(9).
+ * Also masks reserved bits (31-22, 15, 5, 3, 1).
+ */
+#define FLAG_MASK 0x00054dd5
/* set's the trap flag. */
#define TRAP_FLAG 0x100
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