[PARISC] Make sure use of RFI conforms to PA 2.0 and 1.1 arch docs

2.6.12-rc4-pa3 : first pass at making sure use of RFI conforms to
PA 2.0 arch pages F-4 and F-5, PA 1.1 Arch page 3-19 and 3-20.

The discussion revolves around all the rules for clearing PSW Q-bit.
The hard part is meeting all the rules for "relied upon translation".

.align directive is used to guarantee the critical sequence ends more than
8 instructions (32 bytes) from the end of page.

Signed-off-by: Grant Grundler <grundler@parisc-linux.org>

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/include/asm-parisc/assembly.h b/include/asm-parisc/assembly.h
index 30b0234..b24a99e 100644
--- a/include/asm-parisc/assembly.h
+++ b/include/asm-parisc/assembly.h
@@ -450,5 +450,30 @@
 	REST_CR	(%cr22, PT_PSW	(\regs))
 	.endm
 
+
+	/* First step to create a "relied upon translation"
+	 * See PA 2.0 Arch. page F-4 and F-5.
+	 *
+	 * The ssm was originally necessary due to a "PCxT bug".
+	 * But someone decided it needed to be added to the architecture
+	 * and this "feature" went into rev3 of PA-RISC 1.1 Arch Manual.
+	 * It's been carried forward into PA 2.0 Arch as well. :^(
+	 *
+	 * "ssm 0,%r0" is a NOP with side effects (prefetch barrier).
+	 * rsm/ssm prevents the ifetch unit from speculatively fetching
+	 * instructions past this line in the code stream.
+	 * PA 2.0 processor will single step all insn in the same QUAD (4 insn).
+	 */
+	.macro	pcxt_ssm_bug
+	rsm	PSW_SM_I,%r0
+	nop	/* 1 */
+	nop	/* 2 */
+	nop	/* 3 */
+	nop	/* 4 */
+	nop	/* 5 */
+	nop	/* 6 */
+	nop	/* 7 */
+	.endm
+
 #endif /* __ASSEMBLY__ */
 #endif