powerpc: Properly handshake CPUs going out of boot spin loop

We need to wait a bit for them to have done their CPU setup
or we might end up with translation and EE on with different
LPCR values between threads

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index a902a0d3ae0dbda54a11cb070df0aaccb2bc55e5..bb4c033a8fb0a7c57bc760caec2725b2af1adf4f 100644 (file)
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -29,6 +29,7 @@
 #include <asm/percpu.h>
 
 extern int boot_cpuid;
+extern int boot_cpu_count;
 
 extern void cpu_die(void);
 

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 95944278380c44e1b65d018efc6fdae98907aa8a..0700e1135c91a63eb5fa90dedf376e3c479cb030 100644 (file)
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -242,23 +242,31 @@ generic_secondary_common_init:
        ld      r23,0(r23)
        ld      r23,CPU_SPEC_RESTORE(r23)
        cmpdi   0,r23,0
-       beq     4f
+       beq     3f
        ld      r23,0(r23)
        mtctr   r23
        bctrl
 
-3:     HMT_LOW
+3:     LOAD_REG_ADDR(r3, boot_cpu_count) /* Decrement boot_cpu_count */
+       lwarx   r4,0,r3
+       subi    r4,r4,1
+       stwcx.  r4,0,r3
+       bne     3b
+       isync
+
+4:     HMT_LOW
        lbz     r23,PACAPROCSTART(r13)  /* Test if this processor should */
                                        /* start.                        */
 #ifndef CONFIG_SMP
-       b       3b                      /* Never go on non-SMP           */
+       b       4b                      /* Never go on non-SMP           */
 #else
        cmpwi   0,r23,0
-       beq     3b                      /* Loop until told to go         */
+       beq     4b                      /* Loop until told to go         */
 
        sync                            /* order paca.run and cur_cpu_spec */
+       isync                           /* In case code patching happened */
 
-4:     /* Create a temp kernel stack for use before relocation is on.  */
+       /* Create a temp kernel stack for use before relocation is on.  */
        ld      r1,PACAEMERGSP(r13)
        subi    r1,r1,STACK_FRAME_OVERHEAD
 

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index e74fa12afc82b6c35da819f2b4a5f1e02ec42580..c391dc4c8bad8ffa9e028e5d6bfb546c18509de7 100644 (file)
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -268,13 +268,12 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
                                          const char *uname, int depth,
                                          void *data)
 {
-       static int logical_cpuid = 0;
        char *type = of_get_flat_dt_prop(node, "device_type", NULL);
        const u32 *prop;
        const u32 *intserv;
        int i, nthreads;
        unsigned long len;
-       int found = 0;
+       int found = -1;
 
        /* We are scanning "cpu" nodes only */
        if (type == NULL || strcmp(type, "cpu") != 0)
@@ -299,11 +298,8 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
                 * booted proc.
                 */
                if (initial_boot_params && initial_boot_params->version >= 2) {
-                       if (intserv[i] ==
-                                       initial_boot_params->boot_cpuid_phys) {
-                               found = 1;
-                               break;
-                       }
+                       if (intserv[i] == initial_boot_params->boot_cpuid_phys)
+                               found = boot_cpu_count;
                } else {
                        /*
                         * Check if it's the boot-cpu, set it's hw index now,
@@ -311,23 +307,20 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
                         * off secondary threads.
                         */
                        if (of_get_flat_dt_prop(node,
-                                       "linux,boot-cpu", NULL) != NULL) {
-                               found = 1;
-                               break;
-                       }
+                                       "linux,boot-cpu", NULL) != NULL)
+                               found = boot_cpu_count;
                }
-
 #ifdef CONFIG_SMP
                /* logical cpu id is always 0 on UP kernels */
-               logical_cpuid++;
+               boot_cpu_count++;
 #endif
        }
 
-       if (found) {
-               DBG("boot cpu: logical %d physical %d\n", logical_cpuid,
+       if (found >= 0) {
+               DBG("boot cpu: logical %d physical %d\n", found,
                        intserv[i]);
-               boot_cpuid = logical_cpuid;
-               set_hard_smp_processor_id(boot_cpuid, intserv[i]);
+               boot_cpuid = found;
+               set_hard_smp_processor_id(found, intserv[i]);
 
                /*
                 * PAPR defines "logical" PVR values for cpus that

diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 1d2fbc905303401c50bbd410da0118338cb05eb7..620d792b52e471cbd6658dba347f10e95660bf36 100644 (file)
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -48,6 +48,7 @@ extern void bootx_init(unsigned long r4, unsigned long phys);
 
 int boot_cpuid = -1;
 EXPORT_SYMBOL_GPL(boot_cpuid);
+int __initdata boot_cpu_count;
 int boot_cpuid_phys;
 
 int smp_hw_index[NR_CPUS];

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 5a0401fcaebd2b078994d156253de9d2467c6ea7..91a5cc5f0d022237cef58a20317442993d428c8e 100644 (file)
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -72,6 +72,7 @@
 #endif
 
 int boot_cpuid = 0;
+int __initdata boot_cpu_count;
 u64 ppc64_pft_size;
 
 /* Pick defaults since we might want to patch instructions
@@ -233,6 +234,7 @@ void early_setup_secondary(void)
 void smp_release_cpus(void)
 {
        unsigned long *ptr;
+       int i;
 
        DBG(" -> smp_release_cpus()\n");
 
@@ -245,7 +247,16 @@ void smp_release_cpus(void)
        ptr  = (unsigned long *)((unsigned long)&__secondary_hold_spinloop
                        - PHYSICAL_START);
        *ptr = __pa(generic_secondary_smp_init);
-       mb();
+
+       /* And wait a bit for them to catch up */
+       for (i = 0; i < 100000; i++) {
+               mb();
+               HMT_low();
+               if (boot_cpu_count == 0)
+                       break;
+               udelay(1);
+       }
+       DBG("boot_cpu_count = %d\n", boot_cpu_count);
 
        DBG(" <- smp_release_cpus()\n");
 }