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authorEmilio G. Cota <cota@braap.org>2017-07-19 18:57:58 -0400
committerRichard Henderson <richard.henderson@linaro.org>2017-10-24 13:53:42 -0700
commit3468b59e18b179bc63c7ce934de912dfa9596122 (patch)
tree80364d5e448b4d1b820f85845144b6c3497a94b2 /linux-user
parente8feb96fcc6c16eab8923332e86ff4ef0e2ac276 (diff)
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tcg: enable multiple TCG contexts in softmmu
This enables parallel TCG code generation. However, we do not take advantage of it yet since tb_lock is still held during tb_gen_code. In user-mode we use a single TCG context; see the documentation added to tcg_region_init for the rationale. Note that targets do not need any conversion: targets initialize a TCGContext (e.g. defining TCG globals), and after this initialization has finished, the context is cloned by the vCPU threads, each of them keeping a separate copy. TCG threads claim one entry in tcg_ctxs[] by atomically increasing n_tcg_ctxs. Do not be too annoyed by the subsequent atomic_read's of that variable and tcg_ctxs; they are there just to play nice with analysis tools such as thread sanitizer. Note that we do not allocate an array of contexts (we allocate an array of pointers instead) because when tcg_context_init is called, we do not know yet how many contexts we'll use since the bool behind qemu_tcg_mttcg_enabled() isn't set yet. Previous patches folded some TCG globals into TCGContext. The non-const globals remaining are only set at init time, i.e. before the TCG threads are spawned. Here is a list of these set-at-init-time globals under tcg/: Only written by tcg_context_init: - indirect_reg_alloc_order - tcg_op_defs Only written by tcg_target_init (called from tcg_context_init): - tcg_target_available_regs - tcg_target_call_clobber_regs - arm: arm_arch, use_idiv_instructions - i386: have_cmov, have_bmi1, have_bmi2, have_lzcnt, have_movbe, have_popcnt - mips: use_movnz_instructions, use_mips32_instructions, use_mips32r2_instructions, got_sigill (tcg_target_detect_isa) - ppc: have_isa_2_06, have_isa_3_00, tb_ret_addr - s390: tb_ret_addr, s390_facilities - sparc: qemu_ld_trampoline, qemu_st_trampoline (build_trampolines), use_vis3_instructions Only written by tcg_prologue_init: - 'struct jit_code_entry one_entry' - aarch64: tb_ret_addr - arm: tb_ret_addr - i386: tb_ret_addr, guest_base_flags - ia64: tb_ret_addr - mips: tb_ret_addr, bswap32_addr, bswap32u_addr, bswap64_addr Reviewed-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'linux-user')
-rw-r--r--linux-user/syscall.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 9bf901f..d4497de 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -6218,6 +6218,7 @@ static void *clone_func(void *arg)
TaskState *ts;
rcu_register_thread();
+ tcg_register_thread();
env = info->env;
cpu = ENV_GET_CPU(env);
thread_cpu = cpu;