PATCH: Fix 2.6 kernel for the new ia64 assembler

PATCH: Fix 2.6 kernel for the new ia64 assembler

[H. J. Lu]

[-- Attachment #1: Type: text/plain, Size: 304 bytes --]

The new ia64 assembler uses slot 1 for the offset of a long (2-slot)
instruction and the old assembler uses slot 2. The 2.6 kernel assumes
slot 2 and won't boot when the new assembler is used:

http://sources.redhat.com/bugzilla/show_bug.cgi?id=1433

This patch will work with either slot 1 or 2.


H.J.

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--- linux/arch/ia64/kernel/patch.c.slot	2004-10-18 14:54:39.000000000 -0700
+++ linux/arch/ia64/kernel/patch.c	2005-10-07 09:23:04.000000000 -0700
@@ -64,22 +64,30 @@ ia64_patch (u64 insn_addr, u64 mask, u64
 void
 ia64_patch_imm64 (u64 insn_addr, u64 val)
 {
-	ia64_patch(insn_addr,
+	/* The assembler may generate offset pointing to either slot 1
+	   or slot 2 for a long (2-slot) instruction, occupying slots 1
+	   and 2.  */
+  	insn_addr &= -16UL;
+	ia64_patch(insn_addr + 2,
 		   0x01fffefe000UL, (  ((val & 0x8000000000000000UL) >> 27) /* bit 63 -> 36 */
 				     | ((val & 0x0000000000200000UL) <<  0) /* bit 21 -> 21 */
 				     | ((val & 0x00000000001f0000UL) <<  6) /* bit 16 -> 22 */
 				     | ((val & 0x000000000000ff80UL) << 20) /* bit  7 -> 27 */
 				     | ((val & 0x000000000000007fUL) << 13) /* bit  0 -> 13 */));
-	ia64_patch(insn_addr - 1, 0x1ffffffffffUL, val >> 22);
+	ia64_patch(insn_addr + 1, 0x1ffffffffffUL, val >> 22);
 }
 
 void
 ia64_patch_imm60 (u64 insn_addr, u64 val)
 {
-	ia64_patch(insn_addr,
+	/* The assembler may generate offset pointing to either slot 1
+	   or slot 2 for a long (2-slot) instruction, occupying slots 1
+	   and 2.  */
+  	insn_addr &= -16UL;
+	ia64_patch(insn_addr + 2,
 		   0x011ffffe000UL, (  ((val & 0x0800000000000000UL) >> 23) /* bit 59 -> 36 */
 				     | ((val & 0x00000000000fffffUL) << 13) /* bit  0 -> 13 */));
-	ia64_patch(insn_addr - 1, 0x1fffffffffcUL, val >> 18);
+	ia64_patch(insn_addr + 1, 0x1fffffffffcUL, val >> 18);
 }
 
 /*

Re: PATCH: Fix 2.6 kernel for the new ia64 assembler

[David Mosberger-Tang]

Looks fine to me.

  --david

On 10/7/05, H. J. Lu <hjl@lucon.org> wrote:
> The new ia64 assembler uses slot 1 for the offset of a long (2-slot)
> instruction and the old assembler uses slot 2. The 2.6 kernel assumes
> slot 2 and won't boot when the new assembler is used:
>
> http://sources.redhat.com/bugzilla/show_bug.cgi?id\x1433
>
> This patch will work with either slot 1 or 2.
>
>
> H.J.
>
>
>


--
Mosberger Consulting LLC, voice/fax: 510-744-9372,
http://www.mosberger-consulting.com/
35706 Runckel Lane, Fremont, CA 94536

Re: PATCH: Fix 2.6 kernel for the new ia64 assembler

[James E Wilson]

On Fri, 2005-10-07 at 11:01, H. J. Lu wrote:
> The new ia64 assembler uses slot 1 for the offset of a long (2-slot)
> instruction and the old assembler uses slot 2. The 2.6 kernel assumes
> slot 2 and won't boot when the new assembler is used:

Specifically, this is in reference to tags occurring immediately before
a long instruction.

Given something like
	.text
	nop
[L1:]
	movl
The value of L1 should be .text+1 but it was incorrectly .text+2 until
about 2 weeks ago.  Unfortunately, there is code in the kernel that
relies on the incorrect value, and needs to be fixed.  H.J.'s patch
fixes this.

RE: PATCH: Fix 2.6 kernel for the new ia64 assembler

[Magenheimer, Dan (HP Labs Fort Collins)]

Will the fixed code work on both old and new assemblers?
If not, isn't there a potential gcc/kernel version mismatch
problem?

> -----Original Message-----
> From: linux-ia64-owner@vger.kernel.org 
> [mailto:linux-ia64-owner@vger.kernel.org] On Behalf Of James E Wilson
> Sent: Friday, October 07, 2005 12:20 PM
> Cc: linux ia64 kernel
> Subject: Re: PATCH: Fix 2.6 kernel for the new ia64 assembler
> 
> On Fri, 2005-10-07 at 11:01, H. J. Lu wrote:
> > The new ia64 assembler uses slot 1 for the offset of a long (2-slot)
> > instruction and the old assembler uses slot 2. The 2.6 
> kernel assumes
> > slot 2 and won't boot when the new assembler is used:
> 
> Specifically, this is in reference to tags occurring 
> immediately before
> a long instruction.
> 
> Given something like
> 	.text
> 	nop
> [L1:]
> 	movl
> The value of L1 should be .text+1 but it was incorrectly .text+2 until
> about 2 weeks ago.  Unfortunately, there is code in the kernel that
> relies on the incorrect value, and needs to be fixed.  H.J.'s patch
> fixes this.
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe 
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> 

RE: PATCH: Fix 2.6 kernel for the new ia64 assembler

[James E Wilson]

On Fri, 2005-10-07 at 12:27, Magenheimer, Dan (HP Labs Fort Collins)
wrote:
> Will the fixed code work on both old and new assemblers?

Yes.  It is independent of the assembler, at the expense of being
slightly slower than necessary.  The code does an &=-16 to get a bundle
address, then adds 1 or 2 as appropriate to reach each slot.  Ideally,
the &=-16 should not be needed, but it is there to work around the
assembler problem.