[RFC PATCH 10/25] powerpc/book3s64/kuap: Move UAMOR setup to key init function

[Aneesh Kumar K.V]

With hash translation, the kernel will use key 3 for implementing
KUAP feature. Hence the default UAMOR value depends on what other
keys are marked reserved. Move the UAMOR initialization to pkeys init.

Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
---
 arch/powerpc/include/asm/pkeys.h |  1 +
 arch/powerpc/kernel/smp.c        |  3 +++
 arch/powerpc/mm/book3s64/pkeys.c | 25 ++++++++++++++++++++-----
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index b1d448c53209..6e8157f78b52 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -12,6 +12,7 @@
 #include <asm/firmware.h>
 
 extern int max_pkey;
+extern u64 default_uamor;
 extern u32 reserved_allocation_mask; /* bits set for reserved keys */
 
 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 6d2a3a3666f0..5d1e5489bcd2 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -59,6 +59,7 @@
 #include <asm/asm-prototypes.h>
 #include <asm/cpu_has_feature.h>
 #include <asm/ftrace.h>
+#include <asm/pkeys.h>
 
 #ifdef DEBUG
 #include <asm/udbg.h>
@@ -1256,6 +1257,8 @@ void start_secondary(void *unused)
        mmgrab(&init_mm);
        current->active_mm = &init_mm;
 
+       mtspr(SPRN_UAMOR, default_uamor);
+
        smp_store_cpu_info(cpu);
        set_dec(tb_ticks_per_jiffy);
        preempt_disable();
diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
index 727284607fa8..a0406ea32487 100644
--- a/arch/powerpc/mm/book3s64/pkeys.c
+++ b/arch/powerpc/mm/book3s64/pkeys.c
@@ -23,7 +23,7 @@ static u32  initial_allocation_mask;   /* Bits set for the 
initially allocated k
 static u64 default_amr;
 static u64 default_iamr;
 /* Allow all keys to be modified by default */
-static u64 default_uamor = ~0x0UL;
+u64 default_uamor = ~0x0UL;
 /*
  * Key used to implement PROT_EXEC mmap. Denies READ/WRITE
  * We pick key 2 because 0 is special key and 1 is reserved as per ISA.
@@ -112,8 +112,16 @@ void __init pkey_early_init_devtree(void)
        /* scan the device tree for pkey feature */
        pkeys_total = scan_pkey_feature();
        if (!pkeys_total) {
-               /* No support for pkey. Mark it disabled */
-               return;
+               /*
+                * No key support but on radix we can use key 0
+                * to implement kuap.
+                */
+               if (early_radix_enabled())
+                       /*
+                        * Make sure userspace can't change the AMR
+                        */
+                       default_uamor = 0;
+               goto err_out;
        }
 
        cur_cpu_spec->mmu_features |= MMU_FTR_PKEY;
@@ -195,6 +203,12 @@ void __init pkey_early_init_devtree(void)
         */
        initial_allocation_mask |= reserved_allocation_mask;
 
+err_out:
+       /*
+        * Setup uamor on boot cpu
+        */
+       mtspr(SPRN_UAMOR, default_uamor);
+
        return;
 }
 
@@ -230,8 +244,9 @@ void setup_kuap(bool disabled)
                cur_cpu_spec->mmu_features |= MMU_FTR_KUAP;
        }
 
-       /* Make sure userspace can't change the AMR */
-       mtspr(SPRN_UAMOR, 0);
+       /*
+        * Set the default kernel AMR values on all cpus.
+        */
        mtspr(SPRN_AMR, AMR_KUAP_BLOCKED);
        isync();
 }
-- 
2.25.3