ARM: Allow SMP kernels to boot on UP systems
UP systems do not implement all the instructions that SMP systems have,
so in order to boot a SMP kernel on a UP system, we need to rewrite
parts of the kernel.
Do this using an 'alternatives' scheme, where the kernel code and data
is modified prior to initialization to replace the SMP instructions,
thereby rendering the problematical code ineffectual. We use the linker
to generate a list of 32-bit word locations and their replacement values,
and run through these replacements when we detect a UP system.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 7563ff0..df422fe 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -30,15 +30,13 @@
#define TTB_IRGN_WT ((1 << 0) | (0 << 6))
#define TTB_IRGN_WB ((1 << 0) | (1 << 6))
-#ifndef CONFIG_SMP
/* PTWs cacheable, inner WB not shareable, outer WB not shareable */
-#define TTB_FLAGS TTB_IRGN_WB|TTB_RGN_OC_WB
-#define PMD_FLAGS PMD_SECT_WB
-#else
+#define TTB_FLAGS_UP TTB_IRGN_WB|TTB_RGN_OC_WB
+#define PMD_FLAGS_UP PMD_SECT_WB
+
/* PTWs cacheable, inner WBWA shareable, outer WBWA not shareable */
-#define TTB_FLAGS TTB_IRGN_WBWA|TTB_S|TTB_NOS|TTB_RGN_OC_WBWA
-#define PMD_FLAGS PMD_SECT_WBWA|PMD_SECT_S
-#endif
+#define TTB_FLAGS_SMP TTB_IRGN_WBWA|TTB_S|TTB_NOS|TTB_RGN_OC_WBWA
+#define PMD_FLAGS_SMP PMD_SECT_WBWA|PMD_SECT_S
ENTRY(cpu_v7_proc_init)
mov pc, lr
@@ -105,7 +103,8 @@
#ifdef CONFIG_MMU
mov r2, #0
ldr r1, [r1, #MM_CONTEXT_ID] @ get mm->context.id
- orr r0, r0, #TTB_FLAGS
+ ALT_SMP(orr r0, r0, #TTB_FLAGS_SMP)
+ ALT_UP(orr r0, r0, #TTB_FLAGS_UP)
#ifdef CONFIG_ARM_ERRATA_430973
mcr p15, 0, r2, c7, c5, 6 @ flush BTAC/BTB
#endif
@@ -188,7 +187,8 @@
*/
__v7_ca9mp_setup:
#ifdef CONFIG_SMP
- mrc p15, 0, r0, c1, c0, 1
+ ALT_SMP(mrc p15, 0, r0, c1, c0, 1)
+ ALT_UP(mov r0, #(1 << 6)) @ fake it for UP
tst r0, #(1 << 6) @ SMP/nAMP mode enabled?
orreq r0, r0, #(1 << 6) | (1 << 0) @ Enable SMP/nAMP mode and
mcreq p15, 0, r0, c1, c0, 1 @ TLB ops broadcasting
@@ -262,7 +262,8 @@
#ifdef CONFIG_MMU
mcr p15, 0, r10, c8, c7, 0 @ invalidate I + D TLBs
mcr p15, 0, r10, c2, c0, 2 @ TTB control register
- orr r4, r4, #TTB_FLAGS
+ ALT_SMP(orr r4, r4, #TTB_FLAGS_SMP)
+ ALT_UP(orr r4, r4, #TTB_FLAGS_UP)
mcr p15, 0, r4, c2, c0, 1 @ load TTB1
mov r10, #0x1f @ domains 0, 1 = manager
mcr p15, 0, r10, c3, c0, 0 @ load domain access register
@@ -354,10 +355,16 @@
__v7_ca9mp_proc_info:
.long 0x410fc090 @ Required ID value
.long 0xff0ffff0 @ Mask for ID
- .long PMD_TYPE_SECT | \
+ ALT_SMP(.long \
+ PMD_TYPE_SECT | \
PMD_SECT_AP_WRITE | \
PMD_SECT_AP_READ | \
- PMD_FLAGS
+ PMD_FLAGS_SMP)
+ ALT_UP(.long \
+ PMD_TYPE_SECT | \
+ PMD_SECT_AP_WRITE | \
+ PMD_SECT_AP_READ | \
+ PMD_FLAGS_UP)
.long PMD_TYPE_SECT | \
PMD_SECT_XN | \
PMD_SECT_AP_WRITE | \
@@ -380,10 +387,16 @@
__v7_proc_info:
.long 0x000f0000 @ Required ID value
.long 0x000f0000 @ Mask for ID
- .long PMD_TYPE_SECT | \
+ ALT_SMP(.long \
+ PMD_TYPE_SECT | \
PMD_SECT_AP_WRITE | \
PMD_SECT_AP_READ | \
- PMD_FLAGS
+ PMD_FLAGS_SMP)
+ ALT_UP(.long \
+ PMD_TYPE_SECT | \
+ PMD_SECT_AP_WRITE | \
+ PMD_SECT_AP_READ | \
+ PMD_FLAGS_UP)
.long PMD_TYPE_SECT | \
PMD_SECT_XN | \
PMD_SECT_AP_WRITE | \