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authorMichael Matz <matz@suse.de>2014-01-04 22:15:47 +0000
committerPeter Maydell <peter.maydell@linaro.org>2014-01-08 19:07:20 +0000
commitfa2ef212dff8556ea92c4aef54b57efec69ca6fe (patch)
tree45931520fb538132a2279285931369a9cbf7594c /target-arm
parent03d05e2d0765512fb960192b6e9f9a41c47282bd (diff)
target-arm: A64: support for ld/st/cl exclusive
This implement exclusive loads/stores for aarch64 along the lines of arm32 and ppc implementations. The exclusive load remembers the address and loaded value. The exclusive store throws an an exception which uses those values to check for equality in a proper exclusive region. This is not actually the architecture mandated semantics (for either AArch32 or AArch64) but it is close enough for typical guest code sequences to work correctly, and saves us from having to monitor all guest stores. It's fairly easy to come up with test cases where we don't behave like hardware - we don't for example model cache line behaviour. However in the common patterns this works, and the existing 32 bit ARM exclusive access implementation has the same limitations. AArch64 also implements new acquire/release loads/stores (which may be either exclusive or non-exclusive). These imposes extra ordering constraints on memory operations (ie they act as if they have an implicit barrier built into them). As TCG is single-threaded all our barriers are no-ops, so these just behave like normal loads and stores. Signed-off-by: Michael Matz <matz@suse.de> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'target-arm')
-rw-r--r--target-arm/translate-a64.c156
1 files changed, 153 insertions, 3 deletions
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 61974419cd..40c6fc4a9b 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -38,6 +38,15 @@ static TCGv_i64 cpu_X[32];
static TCGv_i64 cpu_pc;
static TCGv_i32 cpu_NF, cpu_ZF, cpu_CF, cpu_VF;
+/* Load/store exclusive handling */
+static TCGv_i64 cpu_exclusive_addr;
+static TCGv_i64 cpu_exclusive_val;
+static TCGv_i64 cpu_exclusive_high;
+#ifdef CONFIG_USER_ONLY
+static TCGv_i64 cpu_exclusive_test;
+static TCGv_i32 cpu_exclusive_info;
+#endif
+
static const char *regnames[] = {
"x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
"x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15",
@@ -70,6 +79,19 @@ void a64_translate_init(void)
cpu_ZF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, ZF), "ZF");
cpu_CF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, CF), "CF");
cpu_VF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, VF), "VF");
+
+ cpu_exclusive_addr = tcg_global_mem_new_i64(TCG_AREG0,
+ offsetof(CPUARMState, exclusive_addr), "exclusive_addr");
+ cpu_exclusive_val = tcg_global_mem_new_i64(TCG_AREG0,
+ offsetof(CPUARMState, exclusive_val), "exclusive_val");
+ cpu_exclusive_high = tcg_global_mem_new_i64(TCG_AREG0,
+ offsetof(CPUARMState, exclusive_high), "exclusive_high");
+#ifdef CONFIG_USER_ONLY
+ cpu_exclusive_test = tcg_global_mem_new_i64(TCG_AREG0,
+ offsetof(CPUARMState, exclusive_test), "exclusive_test");
+ cpu_exclusive_info = tcg_global_mem_new_i32(TCG_AREG0,
+ offsetof(CPUARMState, exclusive_info), "exclusive_info");
+#endif
}
void aarch64_cpu_dump_state(CPUState *cs, FILE *f,
@@ -767,6 +789,11 @@ static void handle_hint(DisasContext *s, uint32_t insn,
}
}
+static void gen_clrex(DisasContext *s, uint32_t insn)
+{
+ tcg_gen_movi_i64(cpu_exclusive_addr, -1);
+}
+
/* CLREX, DSB, DMB, ISB */
static void handle_sync(DisasContext *s, uint32_t insn,
unsigned int op1, unsigned int op2, unsigned int crm)
@@ -778,7 +805,7 @@ static void handle_sync(DisasContext *s, uint32_t insn,
switch (op2) {
case 2: /* CLREX */
- unsupported_encoding(s, insn);
+ gen_clrex(s, insn);
return;
case 4: /* DSB */
case 5: /* DMB */
@@ -1106,10 +1133,133 @@ static void disas_b_exc_sys(DisasContext *s, uint32_t insn)
}
}
-/* Load/store exclusive */
+/*
+ * Load/Store exclusive instructions are implemented by remembering
+ * the value/address loaded, and seeing if these are the same
+ * when the store is performed. This is not actually the architecturally
+ * mandated semantics, but it works for typical guest code sequences
+ * and avoids having to monitor regular stores.
+ *
+ * In system emulation mode only one CPU will be running at once, so
+ * this sequence is effectively atomic. In user emulation mode we
+ * throw an exception and handle the atomic operation elsewhere.
+ */
+static void gen_load_exclusive(DisasContext *s, int rt, int rt2,
+ TCGv_i64 addr, int size, bool is_pair)
+{
+ TCGv_i64 tmp = tcg_temp_new_i64();
+ TCGMemOp memop = MO_TE + size;
+
+ g_assert(size <= 3);
+ tcg_gen_qemu_ld_i64(tmp, addr, get_mem_index(s), memop);
+
+ if (is_pair) {
+ TCGv_i64 addr2 = tcg_temp_new_i64();
+ TCGv_i64 hitmp = tcg_temp_new_i64();
+
+ g_assert(size >= 2);
+ tcg_gen_addi_i64(addr2, addr, 1 << size);
+ tcg_gen_qemu_ld_i64(hitmp, addr2, get_mem_index(s), memop);
+ tcg_temp_free_i64(addr2);
+ tcg_gen_mov_i64(cpu_exclusive_high, hitmp);
+ tcg_gen_mov_i64(cpu_reg(s, rt2), hitmp);
+ tcg_temp_free_i64(hitmp);
+ }
+
+ tcg_gen_mov_i64(cpu_exclusive_val, tmp);
+ tcg_gen_mov_i64(cpu_reg(s, rt), tmp);
+
+ tcg_temp_free_i64(tmp);
+ tcg_gen_mov_i64(cpu_exclusive_addr, addr);
+}
+
+#ifdef CONFIG_USER_ONLY
+static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
+ TCGv_i64 addr, int size, int is_pair)
+{
+ tcg_gen_mov_i64(cpu_exclusive_test, addr);
+ tcg_gen_movi_i32(cpu_exclusive_info,
+ size | is_pair << 2 | (rd << 4) | (rt << 9) | (rt2 << 14));
+ gen_exception_insn(s, 4, EXCP_STREX);
+}
+#else
+static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
+ TCGv_i64 addr, int size, int is_pair)
+{
+ qemu_log_mask(LOG_UNIMP,
+ "%s:%d: system mode store_exclusive unsupported "
+ "at pc=%016" PRIx64 "\n",
+ __FILE__, __LINE__, s->pc - 4);
+}
+#endif
+
+/* C3.3.6 Load/store exclusive
+ *
+ * 31 30 29 24 23 22 21 20 16 15 14 10 9 5 4 0
+ * +-----+-------------+----+---+----+------+----+-------+------+------+
+ * | sz | 0 0 1 0 0 0 | o2 | L | o1 | Rs | o0 | Rt2 | Rn | Rt |
+ * +-----+-------------+----+---+----+------+----+-------+------+------+
+ *
+ * sz: 00 -> 8 bit, 01 -> 16 bit, 10 -> 32 bit, 11 -> 64 bit
+ * L: 0 -> store, 1 -> load
+ * o2: 0 -> exclusive, 1 -> not
+ * o1: 0 -> single register, 1 -> register pair
+ * o0: 1 -> load-acquire/store-release, 0 -> not
+ *
+ * o0 == 0 AND o2 == 1 is un-allocated
+ * o1 == 1 is un-allocated except for 32 and 64 bit sizes
+ */
static void disas_ldst_excl(DisasContext *s, uint32_t insn)
{
- unsupported_encoding(s, insn);
+ int rt = extract32(insn, 0, 5);
+ int rn = extract32(insn, 5, 5);
+ int rt2 = extract32(insn, 10, 5);
+ int is_lasr = extract32(insn, 15, 1);
+ int rs = extract32(insn, 16, 5);
+ int is_pair = extract32(insn, 21, 1);
+ int is_store = !extract32(insn, 22, 1);
+ int is_excl = !extract32(insn, 23, 1);
+ int size = extract32(insn, 30, 2);
+ TCGv_i64 tcg_addr;
+
+ if ((!is_excl && !is_lasr) ||
+ (is_pair && size < 2)) {
+ unallocated_encoding(s);
+ return;
+ }
+
+ if (rn == 31) {
+ gen_check_sp_alignment(s);
+ }
+ tcg_addr = read_cpu_reg_sp(s, rn, 1);
+
+ /* Note that since TCG is single threaded load-acquire/store-release
+ * semantics require no extra if (is_lasr) { ... } handling.
+ */
+
+ if (is_excl) {
+ if (!is_store) {
+ gen_load_exclusive(s, rt, rt2, tcg_addr, size, is_pair);
+ } else {
+ gen_store_exclusive(s, rs, rt, rt2, tcg_addr, size, is_pair);
+ }
+ } else {
+ TCGv_i64 tcg_rt = cpu_reg(s, rt);
+ if (is_store) {
+ do_gpr_st(s, tcg_rt, tcg_addr, size);
+ } else {
+ do_gpr_ld(s, tcg_rt, tcg_addr, size, false, false);
+ }
+ if (is_pair) {
+ TCGv_i64 tcg_rt2 = cpu_reg(s, rt);
+ tcg_gen_addi_i64(tcg_addr, tcg_addr, 1 << size);
+ if (is_store) {
+ do_gpr_st(s, tcg_rt2, tcg_addr, size);
+ } else {
+ do_gpr_ld(s, tcg_rt2, tcg_addr, size, false, false);
+ }
+ }
+ }
}
/*