diff options
| author | Chuck Ebbert <76306.1226@compuserve.com> | 2006-01-05 23:11:29 -0500 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-05 20:50:51 -0800 |
| commit | 9f155b9802bb7049cd0f216c3fe903b58620df11 (patch) | |
| tree | d83fa1699e8113d83588d38a1c16e68cd3fcf462 | |
| parent | 29552b1462799afbe02af035b243e97579d63350 (diff) | |
[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.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c index 5ffbb4b7ad0..5c1fb6aada5 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 |