RE: [PATCH]forbid ptrace changes psr.ri to 3

> This confused me, too, because the changelog and comments say
> "PSR.ri bits 3 are reserved" and "psr.ri bits 11 are reserved".
>
> Something like "PSR.ri value 3 is reserved" would have made
> the intent more clear.

Is this better?  I'd already re-worded it a bit when I was checking
into my GIT tree yesterday ... but I can make more changes if this
is still causing confusion.

commit f8655358b7a6f527a5b102cb7d36b4eb14414860
Author: Shaohua Li <shaohua.li@intel.com>
Date:   Thu Aug 16 10:47:05 2007 -0700

    [IA64] forbid ptrace changes psr.ri to 3
    
    The "ri" field in the processor status register only has defined
    values of 0, 1, 2.  Do not let ptrace set this to 3.  As with
    other reserved fields in registers we silently discard the value.
    
    Signed-off-by: Shaohua Li <shaohua.li@intel.com>
    Signed-off-by: Tony Luck <tony.luck@intel.com>

diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 00f8032..da031f8 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -951,10 +951,14 @@ access_uarea (struct task_struct *child, unsigned long addr,
 			return 0;
 
 		      case PT_CR_IPSR:
-			if (write_access)
-				pt->cr_ipsr = ((*data & IPSR_MASK)
+			if (write_access) {
+				unsigned long tmp = *data;
+				/* psr.ri bits 11 are reserved, ignore the change */
+				if ((tmp & IA64_PSR_RI) == IA64_PSR_RI)
+					tmp &= ~IA64_PSR_RI;
+				pt->cr_ipsr = ((tmp & IPSR_MASK)
 					       | (pt->cr_ipsr & ~IPSR_MASK));
-			else
+			} else
 				*data = (pt->cr_ipsr & IPSR_MASK);
 			return 0;
 
-
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