[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v4] tcg: Toggle page execution for Apple Silicon
|
From: |
Roman Bolshakov |
|
Subject: |
Re: [PATCH v4] tcg: Toggle page execution for Apple Silicon |
|
Date: |
Sat, 23 Jan 2021 21:04:30 +0300 |
On Sat, Jan 23, 2021 at 02:53:49PM +0300, Roman Bolshakov wrote:
> On Thu, Jan 21, 2021 at 08:47:52AM -1000, Richard Henderson wrote:
> > From: Roman Bolshakov <r.bolshakov@yadro.com>
> >
> > Pages can't be both write and executable at the same time on Apple
> > Silicon. macOS provides public API to switch write protection [1] for
> > JIT applications, like TCG.
> >
> > 1.
> > https://developer.apple.com/documentation/apple_silicon/porting_just-in-time_compilers_to_apple_silicon
> >
> > Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
> > Message-Id: <20210113032806.18220-1-r.bolshakov@yadro.com>
> > [rth: Inline the qemu_thread_jit_* functions;
> > drop the MAP_JIT change for a follow-on patch.]
> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> > ---
> >
> > Supercedes: <20210113032806.18220-1-r.bolshakov@yadro.com>
> >
> > This is the version of Roman's patch that I'm queuing to tcg-next.
> > What's missing from the full "Fix execution" patch is setting MAP_JIT
> > for !splitwx in alloc_code_gen_buffer().
> >
>
> Richard, thanks for updating the patch. I have no objections against
> moving the functions and inlining them. However I'm seeing an issue that
> wasn't present in v3:
>
> Process 37109 stopped
> * thread #6,
> stop reason = EXC_BAD_ACCESS (code=1, address=0xfffffffffffffd4f)
> frame #0: 0x00000001002f1c90
> qemu-system-x86_64`tcg_emit_op(opc=INDEX_op_add_i64) at tcg.c:2531:5 [opt]
> 2528 TCGOp *tcg_emit_op(TCGOpcode opc)
> 2529 {
> 2530
> TCGOp *op = tcg_op_alloc(opc);
> -> 2531 QTAILQ_INSERT_TAIL(&tcg_ctx->ops, op, link);
> 2532 return op;
> 2533 }
> 2534
> Target 0: (qemu-system-x86_64) stopped.
> (lldb) bt
> * thread #6, stop reason = EXC_BAD_ACCESS (code=1, address=0xfffffffffffffd4f)
> * frame #0: 0x00000001002f1c90
> qemu-system-x86_64`tcg_emit_op(opc=INDEX_op_add_i64) at tcg.c:2531:5 [opt]
> frame #1: 0x000000010026f040 qemu-system-x86_64`tcg_gen_addi_i64
> [inlined] tcg_gen_op3(opc=INDEX_op_add_i64, a1=4430334952, a2=4430333440,
> a3=4430361496) at tcg-op.c:60:17 [opt]
> frame #2: 0x000000010026f038 qemu-system-x86_64`tcg_gen_addi_i64
> [inlined] tcg_gen_op3_i64(opc=INDEX_op_add_i64, a1=<unavailable>, a2=<unav
> ailable>, a3=<unavailable>) at tcg-op.h:94 [opt]
> frame #3: 0x000000010026f030 qemu-system-x86_64`tcg_gen_addi_i64
> [inlined] tcg_gen_add_i64(ret=<unavailable>, arg1=<unavailable>, arg2=<una
> vailable>) at tcg-op.h:618 [opt]
> frame #4: 0x000000010026f030
> qemu-system-x86_64`tcg_gen_addi_i64(ret=<unavailable>, arg1=<unavailable>,
> arg2=<unavailable>) at tcg-op.c:123
> 5 [opt]
> frame #5: 0x000000010021d1e0
> qemu-system-x86_64`gen_lea_modrm_1(s=<unavailable>, a=(def_seg = 2, base = 5,
> index = -1, scale = 0, disp = -6
> 89)) at translate.c:2101:9 [opt]
> frame #6: 0x000000010020eeec qemu-system-x86_64`disas_insn [inlined]
> gen_lea_modrm(env=0x0000000118610870, s=0x00000001700b6b00, modrm=<una
> vailable>) at translate.c:2111:15 [opt]
> frame #7: 0x000000010020eec0
> qemu-system-x86_64`disas_insn(s=0x00000001700b6b00, cpu=<unavailable>) at
> translate.c:5509 [opt]
> frame #8: 0x000000010020bb44
> qemu-system-x86_64`i386_tr_translate_insn(dcbase=0x00000001700b6b00,
> cpu=<unavailable>) at translate.c:8573:15
> [opt]
> frame #9: 0x00000001002fbcf8
> qemu-system-x86_64`translator_loop(ops=0x0000000100b209c8,
> db=0x00000001700b6b00, cpu=0x0000000118608000, tb=0
> x0000000120017200, max_insns=512) at translator.c:0 [opt]
> frame #10: 0x000000010020b73c
> qemu-system-x86_64`gen_intermediate_code(cpu=<unavailable>, tb=<unavailable>,
> max_insns=<unavailable>) at tra
> nslate.c:8635:5 [opt]
> frame #11: 0x0000000100257970
> qemu-system-x86_64`tb_gen_code(cpu=0x0000000118608000, pc=<unavailable>,
> cs_base=0, flags=4194483, cflags=-16
> 777216) at translate-all.c:1931:5 [opt]
> frame #12: 0x00000001002deb90 qemu-system-x86_64`cpu_exec [inlined]
> tb_find(cpu=0x0000000118608000, last_tb=0x0000000000000000, tb_exit=<un
> available>, cf_mask=0) at cpu-exec.c:456:14 [opt]
> frame #13: 0x00000001002deb54
> qemu-system-x86_64`cpu_exec(cpu=0x0000000118608000) at cpu-exec.c:812 [opt]
> frame #14: 0x00000001002bc0d0
> qemu-system-x86_64`tcg_cpus_exec(cpu=0x0000000118608000) at tcg-cpus.c:57:11
> [opt]
> frame #15: 0x000000010024c2cc
> qemu-system-x86_64`rr_cpu_thread_fn(arg=<unavailable>) at
> tcg-cpus-rr.c:217:21 [opt]
> frame #16: 0x00000001004b00b4
> qemu-system-x86_64`qemu_thread_start(args=<unavailable>) at
> qemu-thread-posix.c:521:9 [opt]
> frame #17: 0x0000000191c4d06c libsystem_pthread.dylib`_pthread_start + 320
>
> I'm looking into the issue but perhaps we'll need v5.
>
Nope. The issue is not directly related to the patch and W^X. I think it
can be applied.
tcg_ctx->ops is somehow getting corrupted despite it's initialized
properly during TCG start:
(lldb) p tcg_ctx->ops
(TCGContext::(anonymous union)) $18 = {
tqh_first = 0x0000008401010000
tqh_circ = {
tql_next = 0x0000008401010000
tql_prev = 0xfffffffffffffd4f
}
}
I've bisected it (with v3 of Apple Silicon fix for TCG) to:
commit 8fe35e0444be88de4e3ab80a2a0e210a1f6d663d
Author: Richard Henderson <richard.henderson@linaro.org>
Date: Mon Mar 30 20:42:43 2020 -0700
tcg/optimize: Use tcg_constant_internal with constant folding
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
tcg/optimize.c | 108 ++++++++++++++++++++++++++-------------------------------
1 file changed, 49 insertions(+), 59 deletions(-)
Although, it crashes with a bit different backtrace than provided above:
Process 17251 stopped
* thread #6, stop reason = EXC_BAD_ACCESS (code=1, address=0x10)
frame #0: 0x00000001002727a8 qemu-system-x86_64`tcg_opt_gen_mov [inlined]
ts_is_copy(ts=<unavailable>) at optimize.c:68:25 [opt]
65
66 static inline bool ts_is_copy(TCGTemp *ts)
67 {
-> 68 return ts_info(ts)->next_copy != ts;
69 }
70
71 /* Reset TEMP's state, possibly removing the temp for the list of
copies. */
Target 0: (qemu-system-x86_64) stopped.
(lldb) bt
* thread #6, stop reason = EXC_BAD_ACCESS (code=1, address=0x10)
* frame #0: 0x00000001002727a8 qemu-system-x86_64`tcg_opt_gen_mov [inlined]
ts_is_copy(ts=<unavailable>) at optimize.c:68:25 [opt]
frame #1: 0x00000001002727a4 qemu-system-x86_64`tcg_opt_gen_mov [inlined]
ts_are_copies(ts1=0x00000001202e8e50, ts2=0x00000001202ef398) at optimize.c:163
[opt]
frame #2: 0x000000010027278c
qemu-system-x86_64`tcg_opt_gen_mov(s=0x00000001202e8000, op=0x0000000119157710,
dst=4834889296, src=4834915224) at optimize.c:191 [opt]
frame #3: 0x0000000100271740
qemu-system-x86_64`tcg_optimize(s=<unavailable>) at optimize.c:0:9 [opt]
frame #4: 0x00000001002f39c4
qemu-system-x86_64`tcg_gen_code(s=0x00000001202e8000, tb=0x0000000128020800) at
tcg.c:4407:5 [opt]
frame #5: 0x00000001002b2688
qemu-system-x86_64`tb_gen_code(cpu=0x0000000118428000, pc=<unavailable>,
cs_base=0, flags=4194483, cflags=-16777216) at translate-all.c:1961:21 [opt]
frame #6: 0x0000000100279460 qemu-system-x86_64`cpu_exec [inlined]
tb_find(cpu=0x0000000118428000, last_tb=0x0000000000000000,
tb_exit=<unavailable>, cf_mask=0) at cpu-exec.c:456:14 [opt]
frame #7: 0x0000000100279424
qemu-system-x86_64`cpu_exec(cpu=0x0000000118428000) at cpu-exec.c:812 [opt]
frame #8: 0x000000010026ea74
qemu-system-x86_64`tcg_cpus_exec(cpu=0x0000000118428000) at tcg-cpus.c:57:11
[opt]
frame #9: 0x0000000100284efc
qemu-system-x86_64`rr_cpu_thread_fn(arg=<unavailable>) at tcg-cpus-rr.c:217:21
[opt]
frame #10: 0x00000001004cffe8
qemu-system-x86_64`qemu_thread_start(args=<unavailable>) at
qemu-thread-posix.c:521:9 [opt]
frame #11: 0x0000000191c4d06c libsystem_pthread.dylib`_pthread_start + 320
The problem is that ts2 in ts_are_copies() contains NULL state_ptr:
(lldb) p *ts2
(TCGTemp) $2 = {
reg = TCG_REG_X0
val_type = TEMP_VAL_DEAD
base_type = TCG_TYPE_I64
type = TCG_TYPE_I64
kind = TEMP_CONST
indirect_reg = 0
indirect_base = 0
mem_coherent = 0
mem_allocated = 0
temp_allocated = 1
val = -690
mem_base = 0x0000000000000000
mem_offset = 0
name = 0x0000000000000000
state = 0
state_ptr = 0x0000000000000000
}
-Roman