tcg: Add atomic helpers

Add all of cmpxchg, op_fetch, fetch_op, and xchg.
Handle both endian-ness, and sizes up to 8.
Handle expanding non-atomically, when emulating in serial.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 109 insertions, 3 deletions

diff --git a/cputlb.c b/cputlb.c
index 82cf46e..4f2c500 100644
--- a/cputlb.c
+++ b/cputlb.c
@@ -23,15 +23,15 @@
 #include "exec/memory.h"
 #include "exec/address-spaces.h"
 #include "exec/cpu_ldst.h"
-
 #include "exec/cputlb.h"
-
 #include "exec/memory-internal.h"
 #include "exec/ram_addr.h"
 #include "exec/exec-all.h"
 #include "tcg/tcg.h"
 #include "qemu/error-report.h"
 #include "exec/log.h"
+#include "exec/helper-proto.h"
+#include "qemu/atomic.h"
 
 /* DEBUG defines, enable DEBUG_TLB_LOG to log to the CPU_LOG_MMU target */
 /* #define DEBUG_TLB */
@@ -585,6 +585,69 @@ void probe_write(CPUArchState *env, target_ulong addr, int mmu_idx,
     }
 }
 
+/* Probe for a read-modify-write atomic operation.  Do not allow unaligned
+ * operations, or io operations to proceed.  Return the host address.  */
+static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr,
+                               TCGMemOpIdx oi, uintptr_t retaddr)
+{
+    size_t mmu_idx = get_mmuidx(oi);
+    size_t index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
+    CPUTLBEntry *tlbe = &env->tlb_table[mmu_idx][index];
+    target_ulong tlb_addr = tlbe->addr_write;
+    TCGMemOp mop = get_memop(oi);
+    int a_bits = get_alignment_bits(mop);
+    int s_bits = mop & MO_SIZE;
+
+    /* Adjust the given return address.  */
+    retaddr -= GETPC_ADJ;
+
+    /* Enforce guest required alignment.  */
+    if (unlikely(a_bits > 0 && (addr & ((1 << a_bits) - 1)))) {
+        /* ??? Maybe indicate atomic op to cpu_unaligned_access */
+        cpu_unaligned_access(ENV_GET_CPU(env), addr, MMU_DATA_STORE,
+                             mmu_idx, retaddr);
+    }
+
+    /* Enforce qemu required alignment.  */
+    if (unlikely(addr & ((1 << s_bits) - 1))) {
+        /* We get here if guest alignment was not requested,
+           or was not enforced by cpu_unaligned_access above.
+           We might widen the access and emulate, but for now
+           mark an exception and exit the cpu loop.  */
+        goto stop_the_world;
+    }
+
+    /* Check TLB entry and enforce page permissions.  */
+    if ((addr & TARGET_PAGE_MASK)
+        != (tlb_addr & (TARGET_PAGE_MASK | TLB_INVALID_MASK))) {
+        if (!VICTIM_TLB_HIT(addr_write, addr)) {
+            tlb_fill(ENV_GET_CPU(env), addr, MMU_DATA_STORE, mmu_idx, retaddr);
+        }
+        tlb_addr = tlbe->addr_write;
+    }
+
+    /* Notice an IO access, or a notdirty page.  */
+    if (unlikely(tlb_addr & ~TARGET_PAGE_MASK)) {
+        /* There's really nothing that can be done to
+           support this apart from stop-the-world.  */
+        goto stop_the_world;
+    }
+
+    /* Let the guest notice RMW on a write-only page.  */
+    if (unlikely(tlbe->addr_read != tlb_addr)) {
+        tlb_fill(ENV_GET_CPU(env), addr, MMU_DATA_LOAD, mmu_idx, retaddr);
+        /* Since we don't support reads and writes to different addresses,
+           and we do have the proper page loaded for write, this shouldn't
+           ever return.  But just in case, handle via stop-the-world.  */
+        goto stop_the_world;
+    }
+
+    return (void *)((uintptr_t)addr + tlbe->addend);
+
+ stop_the_world:
+    cpu_loop_exit_atomic(ENV_GET_CPU(env), retaddr);
+}
+
 #ifdef TARGET_WORDS_BIGENDIAN
 # define TGT_BE(X)  (X)
 # define TGT_LE(X)  BSWAP(X)
@@ -606,8 +669,51 @@ void probe_write(CPUArchState *env, target_ulong addr, int mmu_idx,
 
 #define DATA_SIZE 8
 #include "softmmu_template.h"
-#undef MMUSUFFIX
 
+/* First set of helpers allows passing in of OI and RETADDR.  This makes
+   them callable from other helpers.  */
+
+#define EXTRA_ARGS     , TCGMemOpIdx oi, uintptr_t retaddr
+#define ATOMIC_NAME(X) \
+    HELPER(glue(glue(glue(atomic_ ## X, SUFFIX), END), _mmu))
+#define ATOMIC_MMU_LOOKUP  atomic_mmu_lookup(env, addr, oi, retaddr)
+
+#define DATA_SIZE 1
+#include "atomic_template.h"
+
+#define DATA_SIZE 2
+#include "atomic_template.h"
+
+#define DATA_SIZE 4
+#include "atomic_template.h"
+
+#define DATA_SIZE 8
+#include "atomic_template.h"
+
+/* Second set of helpers are directly callable from TCG as helpers.  */
+
+#undef EXTRA_ARGS
+#undef ATOMIC_NAME
+#undef ATOMIC_MMU_LOOKUP
+#define EXTRA_ARGS         , TCGMemOpIdx oi
+#define ATOMIC_NAME(X)     HELPER(glue(glue(atomic_ ## X, SUFFIX), END))
+#define ATOMIC_MMU_LOOKUP  atomic_mmu_lookup(env, addr, oi, GETPC())
+
+#define DATA_SIZE 1
+#include "atomic_template.h"
+
+#define DATA_SIZE 2
+#include "atomic_template.h"
+
+#define DATA_SIZE 4
+#include "atomic_template.h"
+
+#define DATA_SIZE 8
+#include "atomic_template.h"
+
+/* Code access functions.  */
+
+#undef MMUSUFFIX
 #define MMUSUFFIX _cmmu
 #undef GETPC
 #define GETPC() ((uintptr_t)0)