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target/xtensa: implement exclusive access option

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The Exclusive Instructions provide a general-purpose mechanism for
atomic updates of memory-based synchronization variables that can be
used for exclusion algorithms.

Use cmpxchg-based implementation that is sufficient for the typical use
of exclusive access in atomic operations.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov 2019-04-18 16:37:00 -07:00
parent 98736654f3
commit b345e14053
7 changed files with 200 additions and 2 deletions
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1
target/xtensa/cpu.c
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@ -82,6 +82,7 @@ static void xtensa_cpu_reset(CPUState *s)
XTENSA_OPTION_ATOMCTL) ? 0x28 : 0x15;
env->sregs[CONFIGID0] = env->config->configid[0];
env->sregs[CONFIGID1] = env->config->configid[1];
env->exclusive_addr = -1;
#ifndef CONFIG_USER_ONLY
reset_mmu(env);

2
target/xtensa/cpu.h
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@ -527,6 +527,8 @@ typedef struct CPUXtensaState {
} fregs[16];
float_status fp_status;
uint32_t windowbase_next;
uint32_t exclusive_addr;
uint32_t exclusive_val;
#ifndef CONFIG_USER_ONLY
xtensa_tlb_entry itlb[7][MAX_TLB_WAY_SIZE];

1
target/xtensa/helper.h
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@ -24,6 +24,7 @@ DEF_HELPER_1(check_interrupts, void, env)
DEF_HELPER_2(intset, void, env, i32)
DEF_HELPER_2(intclear, void, env, i32)
DEF_HELPER_3(check_atomctl, void, env, i32, i32)
DEF_HELPER_4(check_exclusive, void, env, i32, i32, i32)
DEF_HELPER_2(wsr_memctl, void, env, i32)
DEF_HELPER_2(itlb_hit_test, void, env, i32)

42
target/xtensa/op_helper.c
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@ -130,6 +130,48 @@ void HELPER(check_atomctl)(CPUXtensaState *env, uint32_t pc, uint32_t vaddr)
}
}
void HELPER(check_exclusive)(CPUXtensaState *env, uint32_t pc, uint32_t vaddr,
uint32_t is_write)
{
uint32_t paddr, page_size, access;
uint32_t atomctl = env->sregs[ATOMCTL];
int rc = xtensa_get_physical_addr(env, true, vaddr, is_write,
xtensa_get_cring(env), &paddr,
&page_size, &access);
if (rc) {
HELPER(exception_cause_vaddr)(env, pc, rc, vaddr);
}
/* When data cache is not configured use ATOMCTL bypass field. */
if (!xtensa_option_enabled(env->config, XTENSA_OPTION_DCACHE)) {
access = PAGE_CACHE_BYPASS;
}
switch (access & PAGE_CACHE_MASK) {
case PAGE_CACHE_WB:
atomctl >>= 2;
/* fall through */
case PAGE_CACHE_WT:
atomctl >>= 2;
/* fall through */
case PAGE_CACHE_BYPASS:
if ((atomctl & 0x3) == 0) {
HELPER(exception_cause_vaddr)(env, pc,
EXCLUSIVE_ERROR_CAUSE, vaddr);
}
break;
case PAGE_CACHE_ISOLATE:
HELPER(exception_cause_vaddr)(env, pc,
LOAD_STORE_ERROR_CAUSE, vaddr);
break;
default:
break;
}
}
void HELPER(wsr_memctl)(CPUXtensaState *env, uint32_t v)
{
if (xtensa_option_enabled(env->config, XTENSA_OPTION_ICACHE)) {

8
target/xtensa/overlay_tool.h
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@ -76,6 +76,10 @@
#define XCHAL_HAVE_MPU 0
#endif
#ifndef XCHAL_HAVE_EXCLUSIVE
#define XCHAL_HAVE_EXCLUSIVE 0
#endif
#define XCHAL_OPTION(xchal, qemu) ((xchal) ? XTENSA_OPTION_BIT(qemu) : 0)
#define XTENSA_OPTIONS ( \
@ -96,8 +100,8 @@
XCHAL_OPTION(XCHAL_HAVE_FP, XTENSA_OPTION_FP_COPROCESSOR) | \
XCHAL_OPTION(XCHAL_HAVE_RELEASE_SYNC, XTENSA_OPTION_MP_SYNCHRO) | \
XCHAL_OPTION(XCHAL_HAVE_S32C1I, XTENSA_OPTION_CONDITIONAL_STORE) | \
XCHAL_OPTION(XCHAL_HAVE_S32C1I && XCHAL_HW_MIN_VERSION >= 230000, \
XTENSA_OPTION_ATOMCTL) | \
XCHAL_OPTION(((XCHAL_HAVE_S32C1I && XCHAL_HW_MIN_VERSION >= 230000) || \
XCHAL_HAVE_EXCLUSIVE), XTENSA_OPTION_ATOMCTL) | \
XCHAL_OPTION(XCHAL_HAVE_DEPBITS, XTENSA_OPTION_DEPBITS) | \
/* Interrupts and exceptions */ \
XCHAL_OPTION(XCHAL_HAVE_EXCEPTIONS, XTENSA_OPTION_EXCEPTION) | \

100
target/xtensa/translate.c
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@ -87,6 +87,8 @@ static TCGv_i32 cpu_BR8[2];
static TCGv_i32 cpu_SR[256];
static TCGv_i32 cpu_UR[256];
static TCGv_i32 cpu_windowbase_next;
static TCGv_i32 cpu_exclusive_addr;
static TCGv_i32 cpu_exclusive_val;
static GHashTable *xtensa_regfile_table;
@ -216,6 +218,14 @@ void xtensa_translate_init(void)
tcg_global_mem_new_i32(cpu_env,
offsetof(CPUXtensaState, windowbase_next),
"windowbase_next");
cpu_exclusive_addr =
tcg_global_mem_new_i32(cpu_env,
offsetof(CPUXtensaState, exclusive_addr),
"exclusive_addr");
cpu_exclusive_val =
tcg_global_mem_new_i32(cpu_env,
offsetof(CPUXtensaState, exclusive_val),
"exclusive_val");
}
void **xtensa_get_regfile_by_name(const char *name)
@ -1592,6 +1602,12 @@ static void translate_clrb_expstate(DisasContext *dc, const OpcodeArg arg[],
tcg_gen_andi_i32(cpu_UR[EXPSTATE], cpu_UR[EXPSTATE], ~(1u << arg[0].imm));
}
static void translate_clrex(DisasContext *dc, const OpcodeArg arg[],
const uint32_t par[])
{
tcg_gen_movi_i32(cpu_exclusive_addr, -1);
}
static void translate_const16(DisasContext *dc, const OpcodeArg arg[],
const uint32_t par[])
{
@ -1667,6 +1683,17 @@ static void translate_extui(DisasContext *dc, const OpcodeArg arg[],
tcg_temp_free(tmp);
}
static void translate_getex(DisasContext *dc, const OpcodeArg arg[],
const uint32_t par[])
{
TCGv_i32 tmp = tcg_temp_new_i32();
tcg_gen_extract_i32(tmp, cpu_SR[ATOMCTL], 8, 1);
tcg_gen_deposit_i32(cpu_SR[ATOMCTL], cpu_SR[ATOMCTL], arg[0].in, 8, 1);
tcg_gen_mov_i32(arg[0].out, tmp);
tcg_temp_free(tmp);
}
static void translate_icache(DisasContext *dc, const OpcodeArg arg[],
const uint32_t par[])
{
@ -1714,6 +1741,38 @@ static void translate_l32e(DisasContext *dc, const OpcodeArg arg[],
tcg_temp_free(addr);
}
#ifdef CONFIG_USER_ONLY
static void gen_check_exclusive(DisasContext *dc, TCGv_i32 addr, bool is_write)
{
}
#else
static void gen_check_exclusive(DisasContext *dc, TCGv_i32 addr, bool is_write)
{
if (!option_enabled(dc, XTENSA_OPTION_MPU)) {
TCGv_i32 tpc = tcg_const_i32(dc->pc);
TCGv_i32 write = tcg_const_i32(is_write);
gen_helper_check_exclusive(cpu_env, tpc, addr, write);
tcg_temp_free(tpc);
tcg_temp_free(write);
}
}
#endif
static void translate_l32ex(DisasContext *dc, const OpcodeArg arg[],
const uint32_t par[])
{
TCGv_i32 addr = tcg_temp_new_i32();
tcg_gen_mov_i32(addr, arg[1].in);
gen_load_store_alignment(dc, 2, addr, true);
gen_check_exclusive(dc, addr, false);
tcg_gen_qemu_ld_i32(arg[0].out, addr, dc->ring, MO_TEUL);
tcg_gen_mov_i32(cpu_exclusive_addr, addr);
tcg_gen_mov_i32(cpu_exclusive_val, arg[0].out);
tcg_temp_free(addr);
}
static void translate_ldst(DisasContext *dc, const OpcodeArg arg[],
const uint32_t par[])
{
@ -2269,6 +2328,33 @@ static void translate_s32e(DisasContext *dc, const OpcodeArg arg[],
tcg_temp_free(addr);
}
static void translate_s32ex(DisasContext *dc, const OpcodeArg arg[],
const uint32_t par[])
{
TCGv_i32 prev = tcg_temp_new_i32();
TCGv_i32 addr = tcg_temp_local_new_i32();
TCGv_i32 res = tcg_temp_local_new_i32();
TCGLabel *label = gen_new_label();
tcg_gen_movi_i32(res, 0);
tcg_gen_mov_i32(addr, arg[1].in);
gen_load_store_alignment(dc, 2, addr, true);
tcg_gen_brcond_i32(TCG_COND_NE, addr, cpu_exclusive_addr, label);
gen_check_exclusive(dc, addr, true);
tcg_gen_atomic_cmpxchg_i32(prev, cpu_exclusive_addr, cpu_exclusive_val,
arg[0].in, dc->cring, MO_TEUL);
tcg_gen_setcond_i32(TCG_COND_EQ, res, prev, cpu_exclusive_val);
tcg_gen_movcond_i32(TCG_COND_EQ, cpu_exclusive_val,
prev, cpu_exclusive_val, prev, cpu_exclusive_val);
tcg_gen_movi_i32(cpu_exclusive_addr, -1);
gen_set_label(label);
tcg_gen_extract_i32(arg[0].out, cpu_SR[ATOMCTL], 8, 1);
tcg_gen_deposit_i32(cpu_SR[ATOMCTL], cpu_SR[ATOMCTL], res, 8, 1);
tcg_temp_free(prev);
tcg_temp_free(addr);
tcg_temp_free(res);
}
static void translate_salt(DisasContext *dc, const OpcodeArg arg[],
const uint32_t par[])
{
@ -3067,6 +3153,9 @@ static const XtensaOpcodeOps core_ops[] = {
}, {
.name = "clrb_expstate",
.translate = translate_clrb_expstate,
}, {
.name = "clrex",
.translate = translate_clrex,
}, {
.name = "const16",
.translate = translate_const16,
@ -3172,6 +3261,9 @@ static const XtensaOpcodeOps core_ops[] = {
}, {
.name = "extw",
.translate = translate_memw,
}, {
.name = "getex",
.translate = translate_getex,
}, {
.name = "hwwdtlba",
.op_flags = XTENSA_OP_ILL,
@ -3243,6 +3335,10 @@ static const XtensaOpcodeOps core_ops[] = {
.name = "l32e",
.translate = translate_l32e,
.op_flags = XTENSA_OP_PRIVILEGED | XTENSA_OP_LOAD,
}, {
.name = "l32ex",
.translate = translate_l32ex,
.op_flags = XTENSA_OP_LOAD,
}, {
.name = (const char * const[]) {
"l32i", "l32i.n", NULL,
@ -4556,6 +4652,10 @@ static const XtensaOpcodeOps core_ops[] = {
.name = "s32e",
.translate = translate_s32e,
.op_flags = XTENSA_OP_PRIVILEGED | XTENSA_OP_STORE,
}, {
.name = "s32ex",
.translate = translate_s32ex,
.op_flags = XTENSA_OP_LOAD | XTENSA_OP_STORE,
}, {
.name = (const char * const[]) {
"s32i", "s32i.n", "s32nb", NULL,

48
tests/tcg/xtensa/test_exclusive.S Normal file
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@ -0,0 +1,48 @@
#include "macros.inc"
test_suite exclusive
#if XCHAL_HAVE_EXCLUSIVE
test exclusive_nowrite
movi a2, 0x29
wsr a2, atomctl
clrex
movi a2, 1f
movi a3, 1
s32ex a3, a2
getex a3
assert eqi, a3, 0
l32i a3, a2, 0
assert eqi, a3, 3
.data
.align 4
1:
.word 3
.text
test_end
test exclusive_write
movi a2, 0x29
wsr a2, atomctl
movi a2, 1f
l32ex a3, a2
assert eqi, a3, 3
movi a3, 2
s32ex a3, a2
getex a3
assert eqi, a3, 1
l32i a3, a2, 0
assert eqi, a3, 2
.data
.align 4
1:
.word 3
.text
test_end
#endif
test_suite_end