sparc64: Store per-cpu offset in trap_block[]

Surprisingly this actually makes LOAD_PER_CPU_BASE() a little
more efficient.

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 11 insertions, 34 deletions

diff --git a/arch/sparc/kernel/head_64.S b/arch/sparc/kernel/head_64.S
index 91bf4c7f79b9..f8f21050448b 100644
--- a/arch/sparc/kernel/head_64.S
+++ b/arch/sparc/kernel/head_64.S
@@ -641,28 +641,6 @@ tlb_fixup_done:
         /* Not reached... */
 
 1:
-        /* If we boot on a non-zero cpu, all of the per-cpu
-         * variable references we make before setting up the
-         * per-cpu areas will use a bogus offset.  Put a
-         * compensating factor into __per_cpu_base to handle
-         * this cleanly.
-         *
-         * What the per-cpu code calculates is:
-         *
-         *      __per_cpu_base + (cpu << __per_cpu_shift)
-         *
-         * These two variables are zero initially, so to
-         * make it all cancel out to zero we need to put
-         * "0 - (cpu << 0)" into __per_cpu_base so that the
-         * above formula evaluates to zero.
-         *
-         * We cannot even perform a printk() until this stuff
-         * is setup as that calls cpu_clock() which uses
-         * per-cpu variables.
-         */
-        sub     %g0, %o0, %o1
-        sethi   %hi(__per_cpu_base), %o2
-        stx     %o1, [%o2 + %lo(__per_cpu_base)]
 #else
         mov     0, %o0
 #endif
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 4226d0ebaea5..b20f253857b7 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1371,23 +1371,17 @@ void smp_send_stop(void)
 {
 }
 
-unsigned long __per_cpu_base __read_mostly;
-unsigned long __per_cpu_shift __read_mostly;
-
-EXPORT_SYMBOL(__per_cpu_base);
-EXPORT_SYMBOL(__per_cpu_shift);
-
 void __init real_setup_per_cpu_areas(void)
 {
-        unsigned long paddr, goal, size, i;
+        unsigned long base, shift, paddr, goal, size, i;
         char *ptr;
 
         /* Copy section for each CPU (we discard the original) */
         goal = PERCPU_ENOUGH_ROOM;
 
-        __per_cpu_shift = PAGE_SHIFT;
+        shift = PAGE_SHIFT;
         for (size = PAGE_SIZE; size < goal; size <<= 1UL)
-                __per_cpu_shift++;
+                shift++;
 
         paddr = lmb_alloc(size * NR_CPUS, PAGE_SIZE);
         if (!paddr) {
@@ -1396,10 +1390,12 @@ void __init real_setup_per_cpu_areas(void)
         }
 
         ptr = __va(paddr);
-        __per_cpu_base = ptr - __per_cpu_start;
+        base = ptr - __per_cpu_start;
 
-        for (i = 0; i < NR_CPUS; i++, ptr += size)
+        for (i = 0; i < NR_CPUS; i++, ptr += size) {
+                __per_cpu_offset(i) = base + (i * size);
                 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
+        }
 
         /* Setup %g5 for the boot cpu.  */
         __local_per_cpu_offset = __per_cpu_offset(smp_processor_id());
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index d809c4ebb48f..d073aabf65ed 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -2509,6 +2509,7 @@ void do_getpsr(struct pt_regs *regs)
 }
 
 struct trap_per_cpu trap_block[NR_CPUS];
+EXPORT_SYMBOL(trap_block);
 
 /* This can get invoked before sched_init() so play it super safe
  * and use hard_smp_processor_id().
@@ -2592,7 +2593,9 @@ void __init trap_init(void)
             (TRAP_PER_CPU_RESUM_QMASK !=
              offsetof(struct trap_per_cpu, resum_qmask)) ||
             (TRAP_PER_CPU_NONRESUM_QMASK !=
-             offsetof(struct trap_per_cpu, nonresum_qmask)))
+             offsetof(struct trap_per_cpu, nonresum_qmask)) ||
+            (TRAP_PER_CPU_PER_CPU_BASE !=
+             offsetof(struct trap_per_cpu, __per_cpu_base)))
                 trap_per_cpu_offsets_are_bolixed_dave();
 
         if ((TSB_CONFIG_TSB !=