powerpc/64: rtas avoid accessing paca in 32-bit mode

Commit 177ba7c647f3 ("powerpc/mm/radix: Limit paca allocation in radix")
limited the paca allocation address to 1G on pSeries because RTAS return
accesses the paca in 32-bit mode:

    On return from RTAS we access the paca variables and we have 64 bit
    disabled. This requires us to limit paca in 32 bit range.

    Fix this by setting ppc64_rma_size to first_memblock_size/1G range.

Avoid this limit by switching to 64-bit mode before accessing any memory.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 36878b6..371c05f 100644 (file)
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -1083,6 +1083,17 @@ __enter_rtas:
 rtas_return_loc:
        FIXUP_ENDIAN
 
+       /*
+        * Clear RI and set SF before anything.
+        */
+       mfmsr   r6
+       li      r0,MSR_RI
+       andc    r6,r6,r0
+       sldi    r0,r0,(MSR_SF_LG - MSR_RI_LG)
+       or      r6,r6,r0
+       sync
+       mtmsrd  r6
+
        /* relocation is off at this point */
        GET_PACA(r4)
        clrldi  r4,r4,2                 /* convert to realmode address */
@@ -1091,12 +1102,6 @@ rtas_return_loc:
 0:     mflr    r3
        ld      r3,(1f-0b)(r3)          /* get &rtas_restore_regs */
 
-       mfmsr   r6
-       li      r0,MSR_RI
-       andc    r6,r6,r0
-       sync    
-       mtmsrd  r6
-        
         ld     r1,PACAR1(r4)           /* Restore our SP */
         ld     r4,PACASAVEDMSR(r4)     /* Restore our MSR */