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>

1 files changed, 12 insertions, 21 deletions

diff --git a/arch/arm/mm/tlb-v7.S b/arch/arm/mm/tlb-v7.S
index f3f288a9546d..53cd5b454673 100644
--- a/arch/arm/mm/tlb-v7.S
+++ b/arch/arm/mm/tlb-v7.S
@@ -13,6 +13,7 @@
  */
 #include <linux/init.h>
 #include <linux/linkage.h>
+#include <asm/assembler.h>
 #include <asm/asm-offsets.h>
 #include <asm/page.h>
 #include <asm/tlbflush.h>
@@ -41,20 +42,15 @@ ENTRY(v7wbi_flush_user_tlb_range)
         orr     r0, r3, r0, lsl #PAGE_SHIFT     @ Create initial MVA
         mov     r1, r1, lsl #PAGE_SHIFT
 1:
-#ifdef CONFIG_SMP
-        mcr     p15, 0, r0, c8, c3, 1           @ TLB invalidate U MVA (shareable) 
-#else
-        mcr     p15, 0, r0, c8, c7, 1           @ TLB invalidate U MVA
-#endif
+        ALT_SMP(mcr     p15, 0, r0, c8, c3, 1)  @ TLB invalidate U MVA (shareable)
+        ALT_UP(mcr      p15, 0, r0, c8, c7, 1)  @ TLB invalidate U MVA
+
         add     r0, r0, #PAGE_SZ
         cmp     r0, r1
         blo     1b
         mov     ip, #0
-#ifdef CONFIG_SMP
-        mcr     p15, 0, ip, c7, c1, 6           @ flush BTAC/BTB Inner Shareable
-#else
-        mcr     p15, 0, ip, c7, c5, 6           @ flush BTAC/BTB
-#endif
+        ALT_SMP(mcr     p15, 0, ip, c7, c1, 6)  @ flush BTAC/BTB Inner Shareable
+        ALT_UP(mcr      p15, 0, ip, c7, c5, 6)  @ flush BTAC/BTB
         dsb
         mov     pc, lr
 ENDPROC(v7wbi_flush_user_tlb_range)
@@ -74,20 +70,14 @@ ENTRY(v7wbi_flush_kern_tlb_range)
         mov     r0, r0, lsl #PAGE_SHIFT
         mov     r1, r1, lsl #PAGE_SHIFT
 1:
-#ifdef CONFIG_SMP
-        mcr     p15, 0, r0, c8, c3, 1           @ TLB invalidate U MVA (shareable)
-#else
-        mcr     p15, 0, r0, c8, c7, 1           @ TLB invalidate U MVA
-#endif
+        ALT_SMP(mcr     p15, 0, r0, c8, c3, 1)  @ TLB invalidate U MVA (shareable)
+        ALT_UP(mcr      p15, 0, r0, c8, c7, 1)  @ TLB invalidate U MVA
         add     r0, r0, #PAGE_SZ
         cmp     r0, r1
         blo     1b
         mov     r2, #0
-#ifdef CONFIG_SMP
-        mcr     p15, 0, r2, c7, c1, 6           @ flush BTAC/BTB Inner Shareable
-#else
-        mcr     p15, 0, r2, c7, c5, 6           @ flush BTAC/BTB
-#endif
+        ALT_SMP(mcr     p15, 0, r2, c7, c1, 6)  @ flush BTAC/BTB Inner Shareable
+        ALT_UP(mcr      p15, 0, r2, c7, c5, 6)  @ flush BTAC/BTB
         dsb
         isb
         mov     pc, lr
@@ -99,5 +89,6 @@ ENDPROC(v7wbi_flush_kern_tlb_range)
 ENTRY(v7wbi_tlb_fns)
         .long   v7wbi_flush_user_tlb_range
         .long   v7wbi_flush_kern_tlb_range
-        .long   v7wbi_tlb_flags
+        ALT_SMP(.long   v7wbi_tlb_flags_smp)
+        ALT_UP(.long    v7wbi_tlb_flags_up)
         .size   v7wbi_tlb_fns, . - v7wbi_tlb_fns