openrisc: Fix jump_label smp syncing

The original commit 8c30b0018f9d ("openrisc: Add jump label support")
copies from arm64 and does not properly consider how icache invalidation
on remote cores works in OpenRISC.  On OpenRISC remote icaches need to
be invalidated otherwise static key's may remain state after updating.

Fix SMP cache syncing by:

 1. Properly invalidate remote core icaches on SMP systems by using
    icache_all_inv.  The old code uses kick_all_cpus_sync() which runs a
    no-op IPI function call on remote CPU's which does execute a lot of
    code and flushes many cache lines in the process, but does not flush
    all and it's not correct on OpenRISC.
 2. For architectures that do not have WRITETHROUGH caches be sure
    to flush the dcache after patching.

To test this I first reproduced the issue using a custom test module
[0].  The test confirmed that some icache lines maintained stale
static_key code sequences after calling static_branch_enable().  After
this patch there are no longer jump_label coherency issues.

[0] https://github.com/stffrdhrn/or1k-utils/tree/master/tests/smp_static_key_test

Cc: stable@vger.kernel.org # depends on openrisc: Add icache_all_inv
Fixes: 8c30b0018f9d ("openrisc: Add jump label support")
Signed-off-by: Stafford Horne <shorne@gmail.com>

diff --git a/arch/openrisc/kernel/jump_label.c b/arch/openrisc/kernel/jump_label.c
index ab7137c23b46c707fc10ccd40e706f9c4ce56037..9cb63f2d2e2b79152f3a5bb1c569d2191f60d740 100644 (file)
--- a/arch/openrisc/kernel/jump_label.c
+++ b/arch/openrisc/kernel/jump_label.c
@@ -47,5 +47,5 @@ bool arch_jump_label_transform_queue(struct jump_entry *entry,
 
 void arch_jump_label_transform_apply(void)
 {
-       kick_all_cpus_sync();
+       icache_all_inv();
 }

diff --git a/arch/openrisc/kernel/patching.c b/arch/openrisc/kernel/patching.c
index d186172beb33770529d6e32073ebd226d04eb4fb..5db027b78bc4029b2afbe91aeba764c1a92d4d05 100644 (file)
--- a/arch/openrisc/kernel/patching.c
+++ b/arch/openrisc/kernel/patching.c
@@ -49,6 +49,9 @@ static int __patch_insn_write(void *addr, u32 insn)
        waddr = patch_map(addr, FIX_TEXT_POKE0);
 
        ret = copy_to_kernel_nofault(waddr, &insn, OPENRISC_INSN_SIZE);
+       if (!IS_ENABLED(CONFIG_DCACHE_WRITETHROUGH))
+               local_dcache_range_flush((unsigned long)waddr,
+                                        (unsigned long)waddr + OPENRISC_INSN_SIZE);
        local_icache_range_inv((unsigned long)waddr,
                               (unsigned long)waddr + OPENRISC_INSN_SIZE);