4 files changed, 69 insertions, 7 deletions

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index bb8e93a76407..c09e3573c5de 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -46,7 +46,8 @@
          * this macro assumes that irqstat (r6) and base (r5) are
          * preserved from get_irqnr_and_base above
          */
-        test_for_ipi r0, r6, r5, lr
+        ALT_SMP(test_for_ipi r0, r6, r5, lr)
+        ALT_UP_B(9997f)
         movne   r0, sp
         adrne   lr, BSYM(1b)
         bne     do_IPI
@@ -57,6 +58,7 @@
         adrne   lr, BSYM(1b)
         bne     do_local_timer
 #endif
+9997:
 #endif
 
         .endm
@@ -965,11 +967,8 @@ kuser_cmpxchg_fixup:
         beq     1b
         rsbs    r0, r3, #0
         /* beware -- each __kuser slot must be 8 instructions max */
-#ifdef CONFIG_SMP
-        b       __kuser_memory_barrier
-#else
-        usr_ret lr
-#endif
+        ALT_SMP(b       __kuser_memory_barrier)
+        ALT_UP(usr_ret  lr)
 
 #endif
 
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index eb62bf947212..b44d21e1e344 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -86,6 +86,9 @@ ENTRY(stext)
         movs    r8, r5                          @ invalid machine (r5=0)?
         beq     __error_a                       @ yes, error 'a'
         bl      __vet_atags
+#ifdef CONFIG_SMP_ON_UP
+        bl      __fixup_smp
+#endif
         bl      __create_page_tables
 
         /*
@@ -333,4 +336,51 @@ __create_page_tables:
 ENDPROC(__create_page_tables)
         .ltorg
 
+#ifdef CONFIG_SMP_ON_UP
+__fixup_smp:
+        mov     r7, #0x00070000
+        orr     r6, r7, #0xff000000     @ mask 0xff070000
+        orr     r7, r7, #0x41000000     @ val 0x41070000
+        and     r0, r9, r6
+        teq     r0, r7                  @ ARM CPU and ARMv6/v7?
+        bne     __fixup_smp_on_up       @ no, assume UP
+
+        orr     r6, r6, #0x0000ff00
+        orr     r6, r6, #0x000000f0     @ mask 0xff07fff0
+        orr     r7, r7, #0x0000b000
+        orr     r7, r7, #0x00000020     @ val 0x4107b020
+        and     r0, r9, r6
+        teq     r0, r7                  @ ARM 11MPCore?
+        moveq   pc, lr                  @ yes, assume SMP
+
+        mrc     p15, 0, r0, c0, c0, 5   @ read MPIDR
+        tst     r0, #1 << 31
+        movne   pc, lr                  @ bit 31 => SMP
+
+__fixup_smp_on_up:
+        adr     r0, 1f
+        ldmia   r0, {r3, r6, r7}
+        sub     r3, r0, r3
+        add     r6, r6, r3
+        add     r7, r7, r3
+2:      cmp     r6, r7
+        ldmia   r6!, {r0, r4}
+        strlo   r4, [r0, r3]
+        blo     2b
+        mov     pc, lr
+ENDPROC(__fixup_smp)
+
+1:      .word   .
+        .word   __smpalt_begin
+        .word   __smpalt_end
+
+        .pushsection .data
+        .globl  smp_on_up
+smp_on_up:
+        ALT_SMP(.long   1)
+        ALT_UP(.long    0)
+        .popsection
+
+#endif
+
 #include "head-common.S"
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index d5231ae7355a..5a82c39ca85e 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -36,6 +36,7 @@
 #include <asm/procinfo.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
+#include <asm/smp_plat.h>
 #include <asm/mach-types.h>
 #include <asm/cacheflush.h>
 #include <asm/cachetype.h>
@@ -825,7 +826,8 @@ void __init setup_arch(char **cmdline_p)
         request_standard_resources(&meminfo, mdesc);
 
 #ifdef CONFIG_SMP
-        smp_init_cpus();
+        if (is_smp())
+                smp_init_cpus();
 #endif
         reserve_crashkernel();
 
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index b16c07914b55..fd5750b8ac84 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -40,6 +40,11 @@ SECTIONS
                 __tagtable_begin = .;
                         *(.taglist.init)
                 __tagtable_end = .;
+#ifdef CONFIG_SMP_ON_UP
+                __smpalt_begin = .;
+                        *(.alt.smp.init)
+                __smpalt_end = .;
+#endif
 
                 INIT_SETUP(16)
 
@@ -237,6 +242,12 @@ SECTIONS
 
         /* Default discards */
         DISCARDS
+
+#ifndef CONFIG_SMP_ON_UP
+        /DISCARD/ : {
+                *(.alt.smp.init)
+        }
+#endif
 }
 
 /*