diff mbox series

[resend] parisc: Don't hardcode assembler bit definitions in tmpalias code

Message ID YoGC6PhtBMnfGA/O@mx3210.localdomain (mailing list archive)
State Accepted, archived
Headers show
Series [resend] parisc: Don't hardcode assembler bit definitions in tmpalias code | expand

Commit Message

John David Anglin May 15, 2022, 10:47 p.m. UTC 
Remove the hardcoded bit definitions in the tmpalias assembly code.
This makes it easy to change the size of the tmpalias region.

The alignment of the tmpalias region is reduced from 16 MB to 8 MB.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
---
diff mbox series

Patch

diff --git a/arch/parisc/include/asm/fixmap.h b/arch/parisc/include/asm/fixmap.h
index e480b2c05407..5cd80ce1163a 100644
--- a/arch/parisc/include/asm/fixmap.h
+++ b/arch/parisc/include/asm/fixmap.h
@@ -9,12 +9,27 @@ 
  *
  * All of the values in this file must be <4GB (because of assembly
  * loading restrictions).  If you place this region anywhere above
- * __PAGE_OFFSET, you must adjust the memory map accordingly */
+ * __PAGE_OFFSET, you must adjust the memory map accordingly
+ */
 
-/* The alias region is used in kernel space to do copy/clear to or
- * from areas congruently mapped with user space.  It is 8MB large
- * and must be 16MB aligned */
-#define TMPALIAS_MAP_START	((__PAGE_OFFSET) - 16*1024*1024)
+/*
+ * The tmpalias region is used in kernel space to copy/clear/flush data
+ * from pages congruently mapped with user space. It is comprised of
+ * a pair regions. The size of these regions is determined by the largest
+ * cache aliasing boundary for machines that support equivalent aliasing.
+ *
+ * The c3750 with PA8700 processor returns an alias value of 11. This
+ * indicates that it has an alias boundary of 4 MB. It also supports
+ * non-equivalent aliasing without a performance penalty.
+ *
+ * Machines with PA8800/PA8900 processors return an alias value of 0.
+ * This indicates the alias boundary is unknown and may be larger than
+ * 16 MB. Non-equivalent aliasing is not supported.
+ *
+ * Here we assume the maximum alias boundary is 4 MB.
+ */
+#define TMPALIAS_SIZE_BITS	22	/* 4 MB */
+#define TMPALIAS_MAP_START	((__PAGE_OFFSET) - (2 << TMPALIAS_SIZE_BITS))
 
 #define FIXMAP_SIZE		(FIX_BITMAP_COUNT << PAGE_SHIFT)
 #define FIXMAP_START		(TMPALIAS_MAP_START - FIXMAP_SIZE)
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index ecf50159359e..2af27c8b4aa6 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -554,8 +554,9 @@ 
 	extrd,s		\pte,63,25,\pte
 	.endm
 
-	/* The alias region is an 8MB aligned 16MB to do clear and
-	 * copy user pages at addresses congruent with the user
+	/* The alias region is comprised of a pair of 4 MB regions
+	 * aligned to 8 MB. It is used to clear/copy/flush user pages
+	 * using kernel virtual addresses congruent with the user
 	 * virtual address.
 	 *
 	 * To use the alias page, you set %r26 up with the to TLB
@@ -571,7 +572,7 @@ 
 	depdi		0,31,32,\tmp
 #endif
 	copy		\va,\tmp1
-	depi		0,31,23,\tmp1
+	depi_safe	0,31,TMPALIAS_SIZE_BITS+1,\tmp1
 	cmpb,COND(<>),n	\tmp,\tmp1,\fault
 	mfctl		%cr19,\tmp	/* iir */
 	/* get the opcode (first six bits) into \tmp */
@@ -605,9 +606,9 @@ 
 	 * Check "subtle" note in pacache.S re: r23/r26.
 	 */
 #ifdef CONFIG_64BIT
-	extrd,u,*=	\va,41,1,%r0
+	extrd,u,*=	\va,63-TMPALIAS_SIZE_BITS,1,%r0
 #else
-	extrw,u,=	\va,9,1,%r0
+	extrw,u,=	\va,31-TMPALIAS_SIZE_BITS,1,%r0
 #endif
 	or,COND(tr)	%r23,%r0,\pte
 	or		%r26,%r0,\pte
diff --git a/arch/parisc/kernel/pacache.S b/arch/parisc/kernel/pacache.S
index 8569141e3e67..45762a9ca064 100644
--- a/arch/parisc/kernel/pacache.S
+++ b/arch/parisc/kernel/pacache.S
@@ -487,6 +487,8 @@  ENDPROC_CFI(copy_page_asm)
  *       parisc chip designers that there will not ever be a parisc
  *       chip with a larger alias boundary (Never say never :-) ).
  *
+ *       Yah, what about the PA8800 and PA8900 processors?
+ *
  *       Subtle: the dtlb miss handlers support the temp alias region by
  *       "knowing" that if a dtlb miss happens within the temp alias
  *       region it must have occurred while in clear_user_page. Since
@@ -545,17 +547,17 @@  ENTRY_CFI(copy_user_page_asm)
 #endif
 	convert_phys_for_tlb_insert20 %r26	/* convert phys addr to tlb insert format */
 	convert_phys_for_tlb_insert20 %r23	/* convert phys addr to tlb insert format */
-	depd		%r24,63,22, %r28	/* Form aliased virtual address 'to' */
+	depd		%r24,63,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depdi		0, 63,PAGE_SHIFT, %r28	/* Clear any offset bits */
 	copy		%r28, %r29
-	depdi		1, 41,1, %r29		/* Form aliased virtual address 'from' */
+	depdi		1, 63-TMPALIAS_SIZE_BITS,1, %r29	/* Form aliased virtual address 'from' */
 #else
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
 	extrw,u		%r23, 24,25, %r23	/* convert phys addr to tlb insert format */
-	depw		%r24, 31,22, %r28	/* Form aliased virtual address 'to' */
+	depw		%r24, 31,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 	copy		%r28, %r29
-	depwi		1, 9,1, %r29		/* Form aliased virtual address 'from' */
+	depwi		1, 31-TMPALIAS_SIZE_BITS,1, %r29	/* Form aliased virtual address 'from' */
 #endif
 
 	/* Purge any old translations */
@@ -691,11 +693,11 @@  ENTRY_CFI(clear_user_page_asm)
 	depdi		0, 31,32, %r28		/* clear any sign extension */
 #endif
 	convert_phys_for_tlb_insert20 %r26	/* convert phys addr to tlb insert format */
-	depd		%r25, 63,22, %r28	/* Form aliased virtual address 'to' */
+	depd		%r25, 63,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depdi		0, 63,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #else
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
-	depw		%r25, 31,22, %r28	/* Form aliased virtual address 'to' */
+	depw		%r25, 31,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #endif
 
@@ -767,11 +769,11 @@  ENTRY_CFI(flush_dcache_page_asm)
 	depdi		0, 31,32, %r28		/* clear any sign extension */
 #endif
 	convert_phys_for_tlb_insert20 %r26	/* convert phys addr to tlb insert format */
-	depd		%r25, 63,22, %r28	/* Form aliased virtual address 'to' */
+	depd		%r25, 63,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depdi		0, 63,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #else
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
-	depw		%r25, 31,22, %r28	/* Form aliased virtual address 'to' */
+	depw		%r25, 31,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #endif
 
@@ -826,11 +828,11 @@  ENTRY_CFI(purge_dcache_page_asm)
 	depdi		0, 31,32, %r28		/* clear any sign extension */
 #endif
 	convert_phys_for_tlb_insert20 %r26	/* convert phys addr to tlb insert format */
-	depd		%r25, 63,22, %r28	/* Form aliased virtual address 'to' */
+	depd		%r25, 63,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depdi		0, 63,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #else
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
-	depw		%r25, 31,22, %r28	/* Form aliased virtual address 'to' */
+	depw		%r25, 31,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #endif
 
@@ -885,11 +887,11 @@  ENTRY_CFI(flush_icache_page_asm)
 	depdi		0, 31,32, %r28		/* clear any sign extension */
 #endif
 	convert_phys_for_tlb_insert20 %r26	/* convert phys addr to tlb insert format */
-	depd		%r25, 63,22, %r28	/* Form aliased virtual address 'to' */
+	depd		%r25, 63,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depdi		0, 63,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #else
 	extrw,u		%r26, 24,25, %r26	/* convert phys addr to tlb insert format */
-	depw		%r25, 31,22, %r28	/* Form aliased virtual address 'to' */
+	depw		%r25, 31,TMPALIAS_SIZE_BITS, %r28	/* Form aliased virtual address 'to' */
 	depwi		0, 31,PAGE_SHIFT, %r28	/* Clear any offset bits */
 #endif