Re: [Qemu-devel] [Bug 1830872] Re: AARCH64 to ARMv7 mistranslation in TCG

[Andrew Randrianasulu <1830872@bugs.launchpad.net>]

В сообщении от Monday 03 June 2019 18:51:40 Alex Bennée написал(а):
> I managed to tweak the memory test enough to detect the failure on
> aarch64-on-armv7 and I the attached patch fixes it. Could you please
> double check with your test case?
> 


Hm, I manually applied path from LP(git diff disliked copypasted patch), 
so for now git diff in qemu tree shows:

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index cdcc377102..b796ab1cbe 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1303,7 +1303,7 @@ load_helper(CPUArchState *env, target_ulong addr, TCGMemOpIdx oi,
         && unlikely((addr & ~TARGET_PAGE_MASK) + size - 1
                     >= TARGET_PAGE_SIZE)) {
         target_ulong addr1, addr2;
-        tcg_target_ulong r1, r2;
+        uint64_t r1, r2;
         unsigned shift;
     do_unaligned_access:
         addr1 = addr & ~(size - 1);
lines 1-13/13 (END)                          

---------

but x86_64-softmmu/qemu-system-x86_64 -kernel /boot/bzImage-4.12.0-x64 -accel tcg
still hangs at 'booting the kernel" (it decompress OK)

I make distclean'ed source tree and reconfigured it:
 ./configure --target-list=x86_64-softmmu --disable-werror --enable-debug-tcg  --cross-cc-x86_64="/opt/kgcc64/bin/x86_64-unknown-linux-gnu-gcc-6.5.0"

next, make -j 5 and test.

Hm.

I tried debug switches, it seems to hang a bit differently for two runs:

x86_64-softmmu/qemu-system-x86_64 -kernel /boot/bzImage-4.12.0-x64
-accel tcg -nographic -d in_asm,op,op_opt,op_ind,out_asm

=====================

IN:
0xffffffff810e8a63:  48 83 c3 64              addq     $0x64, %rbx
0xffffffff810e8a67:  eb c2                    jmp      0xffffffff810e8a2b

OP:
 ld_i32 tmp18,env,$0xfffffff0
 movi_i32 tmp19,$0x0
 brcond_i32 tmp18,tmp19,lt,$L0

 ---- ffffffff810e8a63 0000000000000000
 movi_i32 tmp2,$0x64
 movi_i32 tmp3,$0x0
 mov_i32 tmp0,rbx_0
 mov_i32 tmp1,rbx_1
 add2_i32 tmp0,tmp1,tmp0,tmp1,tmp2,tmp3
 mov_i32 rbx_0,tmp0
 mov_i32 rbx_1,tmp1
 mov_i32 cc_src_0,tmp2
 mov_i32 cc_src_1,tmp3
 mov_i32 cc_dst_0,tmp0
 mov_i32 cc_dst_1,tmp1
 discard cc_src2_0
 discard cc_src2_1
 discard cc_op

 ---- ffffffff810e8a67 0000000000000009
 movi_i32 cc_op,$0x9
 goto_tb $0x0
 movi_i32 tmp6,$0x810e8a2b
 movi_i32 tmp7,$0xffffffff
 st_i32 tmp6,env,$0x80
 st_i32 tmp7,env,$0x84
 exit_tb $0xf2f1c080
 set_label $L0
 exit_tb $0xf2f1c083

OP after optimization and liveness analysis:
 ld_i32 tmp18,env,$0xfffffff0             dead: 1  pref=0xff
 movi_i32 tmp19,$0x0                      pref=0xff
 brcond_i32 tmp18,tmp19,lt,$L0            dead: 0 1

 ---- ffffffff810e8a63 0000000000000000
 movi_i32 tmp2,$0x64                      pref=0xff
 movi_i32 tmp3,$0x0                       pref=0xff
 add2_i32 tmp0,tmp1,rbx_0,rbx_1,tmp2,tmp3  dead: 2 3  pref=0xff,0xff
 mov_i32 rbx_0,tmp0                       sync: 0  dead: 1  pref=0xff
 mov_i32 rbx_1,tmp1                       sync: 0  dead: 1  pref=0xff
 mov_i32 cc_src_0,tmp2                    sync: 0  dead: 0 1  pref=0xff
 mov_i32 cc_src_1,tmp3                    sync: 0  dead: 0 1  pref=0xff
 mov_i32 cc_dst_0,rbx_0                   sync: 0  dead: 0 1  pref=0xff
 mov_i32 cc_dst_1,rbx_1                   sync: 0  dead: 0 1  pref=0xff
 discard cc_src2_0                        pref=0xff
 discard cc_src2_1                        pref=0xff
 discard cc_op                            pref=0xff mov_i32 cc_dst_0,tmp0
 mov_i32 cc_dst_1,tmp1
 discard cc_src2_0
 discard cc_src2_1
 discard cc_op

 ---- ffffffff810e8a55 0000000000000021
 movi_i32 cc_op,$0x21
 movi_i32 tmp20,$0x0
 movi_i32 tmp21,$0x0
 brcond2_i32 cc_dst_0,cc_dst_1,tmp20,tmp21,eq,$L1
 goto_tb $0x0
 movi_i32 tmp6,$0x810e8a57
 movi_i32 tmp7,$0xffffffff
 st_i32 tmp6,env,$0x80
 st_i32 tmp7,env,$0x84
 exit_tb $0xf2f1c180
 set_label $L1
 goto_tb $0x1
 movi_i32 tmp6,$0x810e8a63
 movi_i32 tmp7,$0xffffffff
 st_i32 tmp6,env,$0x80
 st_i32 tmp7,env,$0x84
 exit_tb $0xf2f1c181
 set_label $L0
 exit_tb $0xf2f1c183

OP after optimization and liveness analysis:
 ld_i32 tmp18,env,$0xfffffff0             dead: 1  pref=0xff
 movi_i32 tmp19,$0x0                      pref=0xff
 brcond_i32 tmp18,tmp19,lt,$L0            dead: 0 1

 ---- ffffffff810e8a4c 0000000000000000

 ---- ffffffff810e8a52 0000000000000000
 movi_i32 tmp1,$0x0                       pref=0xff
 movi_i32 tmp0,$0x64                      pref=0xff
 mov_i32 r14_0,tmp0                       sync: 0  dead: 1  pref=0xf8
 mov_i32 r14_1,tmp1                       sync: 0  dead: 1  pref=0xf8
 call cc_compute_c,$0x5,$2,cc_src_0,cc_src_1,cc_dst_0,cc_dst_1,cc_src_0,cc_src_1,cc_src2_0,cc_src2_1,cc_op  sync: 0 1  dead: 0 1 2 3 4 5 6 7 8  pref=none,none
 mov_i32 cc_dst_0,r14_0                   sync: 0  dead: 0 1  pref=0xff
 mov_i32 cc_dst_1,r14_1                   sync: 0  dead: 0 1  pref=0xffУбито

(killed by me)

==================

IN:
0xffffffff810e8a61:  eb ef                    jmp      0xffffffff810e8a52

OP:
 ld_i32 tmp18,env,$0xfffffff0
 movi_i32 tmp19,$0x0
 brcond_i32 tmp18,tmp19,lt,$L0

 ---- ffffffff810e8a61 0000000000000000
 goto_tb $0x0
 movi_i32 tmp6,$0x810e8a52
 movi_i32 tmp7,$0xffffffff
 st_i32 tmp6,env,$0x80
 st_i32 tmp7,env,$0x84
 exit_tb $0xf2f22900
 set_label $L0
 exit_tb $0xf2f22903

OP after optimization and liveness analysis:
 ld_i32 tmp18,env,$0xfffffff0             dead: 1  pref=0xff
 movi_i32 tmp19,$0x0                      pref=0xff
 brcond_i32 tmp18,tmp19,lt,$L0            dead: 0 1

 ---- ffffffff810e8a61 0000000000000000
 goto_tb $0x0
 movi_i32 tmp6,$0x810e8a52                pref=0xff
 movi_i32 tmp7,$0xffffffff                pref=0xff
 st_i32 tmp6,env,$0x80                    dead: 0
 st_i32 tmp7,env,$0x84                    dead: 0 1
 exit_tb $0xf2f22900
 set_label $L0
 exit_tb $0xf2f22903

OUT: [size=56]
0xf2f22980:  8b 5d f0                 movl     -0x10(%ebp), %ebx
0xf2f22983:  85 db                    testl    %ebx, %ebx
0xf2f22985:  0f 8c 23 00 00 00        jl       0xf2f229ae
0xf2f2298b:  e9 00 00 00 00           jmp      0xf2f22990
0xf2f22990:  c7 85 80 00 00 00 52 8a  movl     $0x810e8a52, 0x80(%ebp)
0xf2f22998:  0e 81
0xf2f2299a:  c7 85 84 00 00 00 ff ff  movl     $0xffffffff, 0x84(%ebp)
0xf2f229a2:  ff ff
0xf2f229a4:  b8 00 29 f2 f2           movl     $0xf2f22900, %eax
0xf2f229a9:  e9 69 46 c9 ff           jmp      0xf2bb7017
0xf2f229ae:  b8 03 29 f2 f2           movl     $0xf2f22903, %eax
0xf2f229b3:  e9 5f 46 c9 ff           jmp      0xf2bb7017

----------------
IN:
0xffffffff810e8a52:  49 ff ce                 decq     %r14
0xffffffff810e8a55:  74 0c                    je       0xffffffff810e8a63

OP:
 ld_i32 tmp18,env,$0xfffffff0
 movi_i32 tmp19,$0x0
 brcond_i32 tmp18,tmp19,lt,$L0

 ---- ffffffff810e8a52 0000000000000000
 mov_i32 tmp0,r14_0
 mov_i32 tmp1,r14_1
 mov_i32 tmp0,r14_0
 mov_i32 tmp1,r14_1
 movi_i32 tmp20,$0xffffffff
 movi_i32 tmp21,$0xffffffff
 add2_i32 tmp0,tmp1,tmp0,tmp1,tmp20,tmp21
 mov_i32 r14_0,tmp0
 mov_i32 r14_1,tmp1
 call cc_compute_c,$0x5,$2,cc_src_0,cc_src_1,cc_dst_0,cc_dst_1,cc_src_0,cc_src_1,cc_src2_0,cc_src2_1,cc_op
 mov_i32 cc_dst_0,tmp0
 mov_i32 cc_dst_1,tmp1
 discard cc_src2_0
 discard cc_src2_1
 discard cc_op

 ---- ffffffff810e8a55 0000000000000021 mov_i32 cc_dst_0,r14_0                   sync: 0  dead: 1  pref=0xff
 mov_i32 cc_dst_1,r14_1                   sync: 0  dead: 1  pref=0xff
 discard cc_src2_0                        pref=0xff
 discard cc_src2_1                        pref=0xff
 discard cc_op                            pref=0xff

 ---- ffffffff810e8a55 0000000000000021
 movi_i32 cc_op,$0x21                     sync: 0  dead: 0  pref=0xff
 movi_i32 tmp20,$0x0                      pref=0xff
 movi_i32 tmp21,$0x0                      pref=0xff
 brcond2_i32 cc_dst_0,cc_dst_1,tmp20,tmp21,eq,$L1  dead: 0 1 2 3
 goto_tb $0x0
 movi_i32 tmp6,$0x810e8a57                pref=0xff
 movi_i32 tmp7,$0xffffffff                pref=0xff
 st_i32 tmp6,env,$0x80                    dead: 0
 st_i32 tmp7,env,$0x84                    dead: 0 1
 exit_tb $0xf2f229c0
 set_label $L1
 goto_tb $0x1
 movi_i32 tmp6,$0x810e8a63                pref=0xff movi_i32 cc_op,$0x9                      sync: 0  dead: 0  pref=0xff
 goto_tb $0x0
 movi_i32 tmp6,$0x810e8a2b                pref=0xff
 movi_i32 tmp7,$0xffffffff                pref=0xff
 st_i32 tmp6,env,$0x80                    dead: 0
 st_i32 tmp7,env,$0x84                    dead: 0 1
 exit_tb $0xf2f22b40
 set_label $L0
 exit_tb $0xf2f22b43

OUT: [size=116]
0xf2f22bc0:  8b 5d f0                 movl     -0x10(%ebp), %ebx
0xf2f22bc3:  85 db                    testl    %ebx, %ebx
0xf2f22bc5:  0f 8c 5f 00 00 00        jl       0xf2f22c2a
0xf2f22bcb:  8b 5d 18                 movl     0x18(%ebp), %ebx
0xf2f22bce:  8b 75 1c                 movl     0x1c(%ebp), %esi
0xf2f22bd1:  83 c3 64                 addl     $0x64, %ebx
0xf2f22bd4:  83 d6 00                 adcl     $0, %esi
0xf2f22bd7:  89 5d 18                 movl     %ebx, 0x18(%ebp)
Убито

=============================

try kernel I use (it works with qemu compiiled under 64-bit Slackware,
and also with kvm on 32-bit x86)

sha256sum /boot/bzImage-4.12.0-x64
b4183376de17e8ea7a25094b7a526e99bcb8339b8703090684c93e0e0a50d284  /boot/bzImage-4.12.0-x64

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https://bugs.launchpad.net/bugs/1830872

Title:
  AARCH64 to ARMv7 mistranslation in TCG

Status in QEMU:
  New

Bug description:
  The following guest code:

  https://github.com/tianocore/edk2/blob/3604174718e2afc950c3cc64c64ba5165c8692bd/MdePkg/Library/BaseMemoryLibOptDxe/AArch64/CopyMem.S

  implements, in hand-optimized aarch64 assembly, the CopyMem() edk2 (EFI
  Development Kit II) library function. (CopyMem() basically has memmove()
  semantics, to provide a standard C analog here.) The relevant functions
  are InternalMemCopyMem() and __memcpy().

  When TCG translates this aarch64 code to x86_64, everything works
  fine.

  When TCG translates this aarch64 code to ARMv7, the destination area of
  the translated CopyMem() function becomes corrupted -- it differs from
  the intended source contents. Namely, in every 4096 byte block, the
  8-byte word at offset 4032 (0xFC0) is zeroed out in the destination,
  instead of receiving the intended source value.

  I'm attaching two hexdumps of the same destination area:

  - "good.txt" is a hexdump of the destination area when CopyMem() was
    translated to x86_64,

  - "bad.txt" is a hexdump of the destination area when CopyMem() was
    translated to ARMv7.

  In order to assist with the analysis of this issue, I disassembled the
  aarch64 binary with "objdump". Please find the listing in
  "DxeCore.objdump", attached. The InternalMemCopyMem() function starts at
  hex offset 2b2ec. The __memcpy() function starts at hex offset 2b180.

  And, I ran the guest on the ARMv7 host with "-d
  in_asm,op,op_opt,op_ind,out_asm". Please find the log in
  "tcg.in_asm.op.op_opt.op_ind.out_asm.log", attached.

  The TBs that correspond to (parts of) the InternalMemCopyMem() and
  __memcpy() functions are scattered over the TCG log file, but the offset
  between the "nice" disassembly from "DxeCore.objdump", and the in-RAM
  TBs in the TCG log, can be determined from the fact that there is a
  single prfm instruction in the entire binary. The instruction's offset
  is 0x2b180 in "DxeCore.objdump" -- at the beginning of the __memcpy()
  function --, and its RAM address is 0x472d2180 in the TCG log. Thus the
  difference (= the load address of DxeCore.efi) is 0x472a7000.

  QEMU was built at commit a4f667b67149 ("Merge remote-tracking branch
  'remotes/cohuck/tags/s390x-20190521-3' into staging", 2019-05-21).

  The reproducer command line is (on an ARMv7 host):

    qemu-system-aarch64 \
      -display none \
      -machine virt,accel=tcg \
      -nodefaults \
      -nographic \
      -drive if=pflash,format=raw,file=$prefix/share/qemu/edk2-aarch64-code.fd,readonly \
      -drive if=pflash,format=raw,file=$prefix/share/qemu/edk2-arm-vars.fd,snapshot=on \
      -cpu cortex-a57 \
      -chardev stdio,signal=off,mux=on,id=char0 \
      -mon chardev=char0,mode=readline \
      -serial chardev:char0

  The apparent symptom is an assertion failure *in the guest*, such as

  > ASSERT [DxeCore]
  > /home/lacos/src/upstream/qemu/roms/edk2/MdePkg/Library/BaseLib/String.c(1090):
  > Length < _gPcd_FixedAtBuild_PcdMaximumAsciiStringLength

  but that is only a (distant) consequence of the CopyMem()
  mistranslation, and resultant destination area corruption.

  Originally reported in the following two mailing list messages:
  - http://mid.mail-archive.com/9d2e260c-c491-03d2-9b8b-b57b72083f77@redhat.com
  - http://mid.mail-archive.com/f1cec8c0-1a9b-f5bb-f951-ea0ba9d276ee@redhat.com

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