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[PATCH] i386: PTRACE_POKEUSR: allow changing RF bit in EFLAGS register.

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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>
This commit is contained in:
Chuck Ebbert 2006-01-05 23:11:29 -05:00 committed by Linus Torvalds
parent 29552b1462
commit 9f155b9802
1 changed files with 6 additions and 3 deletions
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9
arch/i386/kernel/ptrace.c
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@ -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