Re: flush_icache_range

Zoltan Menyhart
2005-06-03T12:35:52Z

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David, Jim,

Here is my next try. I hope I have not missed out anything.

Thanks,

Zoltan

P.S.: next week I'll be away, should there be some minor problems...

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--- linux-2.6.11-orig/arch/ia64/lib/flush.S 2005-04-26 15:59:49.000000000 +0200
+++ linux-2.6.11/arch/ia64/lib/flush.S 2005-06-03 14:11:09.069041791 +0200
@@ -3,37 +3,59 @@
*
* Copyright (C) 1999-2001 Hewlett-Packard Co
* Copyright (C) 1999-2001 David Mosberger-Tang <davidm@hpl.hp.com>
+ *
+ * 05/28/05 Zoltan Menyhart Dynamic stride size
*/
+
#include <asm/asmmacro.h>
-#include <asm/page.h>
+

/*
* flush_icache_range(start,end)
- * Must flush range from start to end-1 but nothing else (need to
+ *
+ * Make i-cache(s) coherent with d-caches.
+ *
+ * Must deal with range from start to end-1 but nothing else (need to
* be careful not to touch addresses that may be unmapped).
+ *
+ * Note: "in0" and "in1" are preserved for debugging purposes.
*/
GLOBAL_ENTRY(flush_icache_range)
+
.prologue
- alloc r2=ar.pfs,2,0,0,0
- sub r8=in1,in0,1
- ;;
- shr.u r8=r8,5 // we flush 32 bytes per iteration
- .save ar.lc, r3
- mov r3=ar.lc // save ar.lc
+ alloc r2=ar.pfs,2,0,0,0
+ movl r3=ia64_i_cache_stride_shift
+ mov r21=1
+ ;;
+ ld8 r20=[r3] // r20: stride shift
+ sub r22=in1,r0,1 // last byte address
+ ;;
+ shr.u r23=in0,r20 // start / (stride size)
+ shr.u r22=r22,r20 // (last byte address) / (stride size)
+ shl r21=r21,r20 // r21: stride size of the i-cache(s)
+ ;;
+ sub r8=r22,r23 // number of strides - 1
+ shl r24=r23,r20 // r24: addresses for "fc.i" =
+ // "start" rounded down to stride boundary
+ .save ar.lc,r3
+ mov r3=ar.lc // save ar.lc
;;

.body
-
- mov ar.lc=r8
+ mov ar.lc=r8
;;
-.Loop: fc in0 // issuable on M0 only
- add in0=32,in0
+ /*
+ * 32 byte aligned loop, even number of (actually 2) bundles
+ */
+.Loop: fc.i r24 // issuable on M0 only
+ add r24=r21,r24 // we flush "stride size" bytes per iteration
+ nop.i 0
br.cloop.sptk.few .Loop
;;
sync.i
;;
srlz.i
;;
- mov ar.lc=r3 // restore ar.lc
+ mov ar.lc=r3 // restore ar.lc
br.ret.sptk.many rp
END(flush_icache_range)
--- linux-2.6.11-orig/arch/ia64/kernel/setup.c 2005-04-26 15:59:49.000000000 +0200
+++ linux-2.6.11/arch/ia64/kernel/setup.c 2005-06-03 14:06:23.779006224 +0200
@@ -15,6 +15,7 @@
* 02/01/00 R.Seth fixed get_cpuinfo for SMP
* 01/07/99 S.Eranian added the support for command line argument
* 06/24/99 W.Drummond added boot_cpu_data.
+ * 05/28/05 Z. Menyhart Dynamic stride size for "flush_icache_range()"
*/
#include <linux/config.h>
#include <linux/module.h>
@@ -78,6 +79,13 @@
EXPORT_SYMBOL(io_space);
unsigned int num_io_spaces;

+/*
+ * "flush_icache_range()" needs to know what processor dependent stride size to use
+ * when it makes i-cache(s) coherent with d-caches.
+ */
+#define I_CACHE_STRIDE_SHIFT 5 /* Safest way to go: 32 bytes by 32 bytes */
+unsigned long ia64_i_cache_stride_shift = ~0;
+
unsigned char aux_device_present = 0xaa; /* XXX remove this when legacy I/O is gone */

/*
@@ -590,6 +598,12 @@
/* start_kernel() requires this... */
}

+/*
+ * Calculate the max. cache line size.
+ *
+ * In addition, the minimum of the i-cache stride sizes is calculated for
+ * "flush_icache_range()".
+ */
static void
get_max_cacheline_size (void)
{
@@ -603,6 +617,8 @@
printk(KERN_ERR "%s: ia64_pal_cache_summary() failed (status=%ld)\n",
__FUNCTION__, status);
max = SMP_CACHE_BYTES;
+ /* Safest setup for "flush_icache_range()" */
+ ia64_i_cache_stride_shift = I_CACHE_STRIDE_SHIFT;
goto out;
}

@@ -611,14 +627,31 @@
&cci);
if (status != 0) {
printk(KERN_ERR
- "%s: ia64_pal_cache_config_info(l=%lu) failed (status=%ld)\n",
+ "%s: ia64_pal_cache_config_info(l=%lu, 2) failed (status=%ld)\n",
__FUNCTION__, l, status);
max = SMP_CACHE_BYTES;
+ /* The safest setup for "flush_icache_range()" */
+ cci.pcci_stride = I_CACHE_STRIDE_SHIFT;
+ cci.pcci_unified = 1;
}
line_size = 1 << cci.pcci_line_size;
if (line_size > max)
max = line_size;
- }
+ if (!cci.pcci_unified) {
+ status = ia64_pal_cache_config_info(l,
+ /* cache_type (instruction)= */ 1,
+ &cci);
+ if (status != 0) {
+ printk(KERN_ERR
+ "%s: ia64_pal_cache_config_info(l=%lu, 1) failed (status=%ld)\n",
+ __FUNCTION__, l, status);
+ /* The safest setup for "flush_icache_range()" */
+ cci.pcci_stride = I_CACHE_STRIDE_SHIFT;
+ }
+ }
+ if (cci.pcci_stride < ia64_i_cache_stride_shift)
+ ia64_i_cache_stride_shift = cci.pcci_stride;
+ }
out:
if (max > ia64_max_cacheline_size)
ia64_max_cacheline_size = max;