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accel/tcg: Add fast path for translator_ld*

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Cache the translation from guest to host address, so we may
use direct loads when we hit on the primary translation page.

Look up the second translation page only once, during translation.
This obviates another lookup of the second page within tb_gen_code
after translation.

Fixes a bug in that plugin_insn_append should be passed the bytes
in the original memory order, not bswapped by pieces.

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-08-10 21:39:29 -07:00
parent 306c872103
commit 50627f1b7b
3 changed files with 141 additions and 71 deletions
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126
accel/tcg/translator.c
View file

@ -42,15 +42,6 @@ bool translator_use_goto_tb(DisasContextBase *db, target_ulong dest)
return ((db->pc_first ^ dest) & TARGET_PAGE_MASK) == 0;
}
static inline void translator_page_protect(DisasContextBase *dcbase,
target_ulong pc)
{
#ifdef CONFIG_USER_ONLY
dcbase->page_protect_end = pc | ~TARGET_PAGE_MASK;
page_protect(pc);
#endif
}
void translator_loop(CPUState *cpu, TranslationBlock *tb, int max_insns,
target_ulong pc, void *host_pc,
const TranslatorOps *ops, DisasContextBase *db)
@ -66,7 +57,12 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int max_insns,
db->num_insns = 0;
db->max_insns = max_insns;
db->singlestep_enabled = cflags & CF_SINGLE_STEP;
translator_page_protect(db, db->pc_next);
db->host_addr[0] = host_pc;
db->host_addr[1] = NULL;
#ifdef CONFIG_USER_ONLY
page_protect(pc);
#endif
ops->init_disas_context(db, cpu);
tcg_debug_assert(db->is_jmp == DISAS_NEXT); /* no early exit */
@ -151,31 +147,103 @@ void translator_loop(CPUState *cpu, TranslationBlock *tb, int max_insns,
#endif
}
static inline void translator_maybe_page_protect(DisasContextBase *dcbase,
target_ulong pc, size_t len)
static void *translator_access(CPUArchState *env, DisasContextBase *db,
target_ulong pc, size_t len)
{
#ifdef CONFIG_USER_ONLY
target_ulong end = pc + len - 1;
void *host;
target_ulong base, end;
TranslationBlock *tb;
if (end > dcbase->page_protect_end) {
translator_page_protect(dcbase, end);
tb = db->tb;
/* Use slow path if first page is MMIO. */
if (unlikely(tb->page_addr[0] == -1)) {
return NULL;
}
end = pc + len - 1;
if (likely(is_same_page(db, end))) {
host = db->host_addr[0];
base = db->pc_first;
} else {
host = db->host_addr[1];
base = TARGET_PAGE_ALIGN(db->pc_first);
if (host == NULL) {
tb->page_addr[1] =
get_page_addr_code_hostp(env, base, &db->host_addr[1]);
#ifdef CONFIG_USER_ONLY
page_protect(end);
#endif
/* We cannot handle MMIO as second page. */
assert(tb->page_addr[1] != -1);
host = db->host_addr[1];
}
/* Use slow path when crossing pages. */
if (is_same_page(db, pc)) {
return NULL;
}
}
tcg_debug_assert(pc >= base);
return host + (pc - base);
}
#define GEN_TRANSLATOR_LD(fullname, type, load_fn, swap_fn) \
type fullname ## _swap(CPUArchState *env, DisasContextBase *dcbase, \
abi_ptr pc, bool do_swap) \
{ \
translator_maybe_page_protect(dcbase, pc, sizeof(type)); \
type ret = load_fn(env, pc); \
if (do_swap) { \
ret = swap_fn(ret); \
} \
plugin_insn_append(pc, &ret, sizeof(ret)); \
return ret; \
uint8_t translator_ldub(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
{
uint8_t ret;
void *p = translator_access(env, db, pc, sizeof(ret));
if (p) {
plugin_insn_append(pc, p, sizeof(ret));
return ldub_p(p);
}
ret = cpu_ldub_code(env, pc);
plugin_insn_append(pc, &ret, sizeof(ret));
return ret;
}
FOR_EACH_TRANSLATOR_LD(GEN_TRANSLATOR_LD)
uint16_t translator_lduw(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
{
uint16_t ret, plug;
void *p = translator_access(env, db, pc, sizeof(ret));
#undef GEN_TRANSLATOR_LD
if (p) {
plugin_insn_append(pc, p, sizeof(ret));
return lduw_p(p);
}
ret = cpu_lduw_code(env, pc);
plug = tswap16(ret);
plugin_insn_append(pc, &plug, sizeof(ret));
return ret;
}
uint32_t translator_ldl(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
{
uint32_t ret, plug;
void *p = translator_access(env, db, pc, sizeof(ret));
if (p) {
plugin_insn_append(pc, p, sizeof(ret));
return ldl_p(p);
}
ret = cpu_ldl_code(env, pc);
plug = tswap32(ret);
plugin_insn_append(pc, &plug, sizeof(ret));
return ret;
}
uint64_t translator_ldq(CPUArchState *env, DisasContextBase *db, abi_ptr pc)
{
uint64_t ret, plug;
void *p = translator_access(env, db, pc, sizeof(ret));
if (p) {
plugin_insn_append(pc, p, sizeof(ret));
return ldq_p(p);
}
ret = cpu_ldq_code(env, pc);
plug = tswap64(ret);
plugin_insn_append(pc, &plug, sizeof(ret));
return ret;
}