On 9/25/22 22:28, John David Anglin wrote:
On 2022-09-25 4:11 p.m., Helge Deller wrote:
n 9/25/22 22:02, John David Anglin wrote:
On 2022-09-25 2:57 p.m., Helge Deller wrote:
+#ifdef CONFIG_PA20
+#define ALT_COND_PACACHE ALT_COND_ALWAYS
+#else
+#define ALT_COND_PACACHE ALT_COND_NO_SMP
+#endif
+
ENTRY_CFI(flush_tlb_all_local)
/*
* The pitlbe and pdtlbe instructions should only be used to
@@ -539,15 +545,10 @@ ENTRY_CFI(copy_user_page_asm)
/* Purge any old translations */
-#ifdef CONFIG_PA20
- pdtlb,l %r0(%r28)
- pdtlb,l %r0(%r29)
-#else
0: pdtlb %r0(%r28)
1: pdtlb %r0(%r29)
- ALTERNATIVE(0b, 0b+4, ALT_COND_NO_SMP, INSN_PxTLB)
- ALTERNATIVE(1b, 1b+4, ALT_COND_NO_SMP, INSN_PxTLB)
-#endif
+ ALTERNATIVE(0b, 0b+4, ALT_COND_PACACHE, INSN_PxTLB)
+ ALTERNATIVE(1b, 1b+4, ALT_COND_PACACHE, INSN_PxTLB)
This doesn't look correct. If ALT_COND_PACACHE is defined as ALT_COND_NO_SMP, the pdtlb
instructions will be converted to pdtlb,l instructions when running UP. These are not supported
on PA 1.1.
Your concern is correct, but there is an additonal check in the alternative-coding,
which prevents enabling the local flag if we're not running on a PA2.0 CPU.
So, those ALTERNATIVE() macros will only apply on PA2.0 machines.
You are correct. Missed that.
That only leaves the bus serialization issue when pdtlb is used on an SMP machine.
I think we are Ok with what's in the kernel already.
According to arch/parisc/include/asm/pgtable.h:
* This is for the serialization of PxTLB broadcasts. At least on the N class
* systems, only one PxTLB inter processor broadcast can be active at any one
* time on the Merced bus. */
extern spinlock_t pa_tlb_flush_lock;
#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
extern int pa_serialize_tlb_flushes;
#else
#define pa_serialize_tlb_flushes (0)
#endif
we currently do TLB serialization on 64-bit machines with a 64-bit kernel only.
N-class machines are 64-bit-only machines which can't run a 32-bit kernel.
So, 32-bit SMP kernels (which don't have serialization for PxTLB flushes)
don't seem to be affected.
Helge
