Re: [PULL v3 00/20] tcg patch queue

[Ilya Leoshkevich]

On Tue, 2022-09-20 at 12:27 +0200, Thomas Huth wrote:
> On 06/09/2022 10.37, Richard Henderson wrote:
> > v2: Fix incorretly resolved rebase conflict in patch 16.
> > v3: Work around clang preprocessor bug in patch 3.
> > 
> > 
> > r~
> > 
> > 
> > The following changes since commit
> > fd28528ece590dc709d1a893fce2ff2f68ddca70:
> > 
> >    Merge tag 'pull-or1k-20220904' of
> > https://github.com/stffrdhrn/qemu into staging (2022-09-05 18:01:02
> > -0400)
> > 
> > are available in the Git repository at:
> > 
> >    https://gitlab.com/rth7680/qemu.git tags/pull-tcg-20220906
> > 
> > for you to fetch changes up to
> > 00c07344fa245b22e895b363320ba4cd0ec1088a:
> > 
> >    target/riscv: Make translator stop before the end of a page
> > (2022-09-06 08:04:26 +0100)
> > 
> > ----------------------------------------------------------------
> > Respect PROT_EXEC in user-only mode.
> > Fix s390x, i386 and riscv for translations crossing a page.
> > 
> > ----------------------------------------------------------------
> > Ilya Leoshkevich (4):
> >        linux-user: Clear translations on mprotect()
> >        accel/tcg: Introduce is_same_page()
> >        target/s390x: Make translator stop before the end of a page
> >        target/i386: Make translator stop before the end of a page
> > 
> > Richard Henderson (16):
> >        linux-user/arm: Mark the commpage executable
> >        linux-user/hppa: Allocate page zero as a commpage
> >        linux-user/x86_64: Allocate vsyscall page as a commpage
> >        linux-user: Honor PT_GNU_STACK
> >        tests/tcg/i386: Move smc_code2 to an executable section
> >        accel/tcg: Properly implement get_page_addr_code for user-
> > only
> >        accel/tcg: Unlock mmap_lock after longjmp
> >        accel/tcg: Make tb_htable_lookup static
> >        accel/tcg: Move qemu_ram_addr_from_host_nofail to physmem.c
> >        accel/tcg: Use probe_access_internal for softmmu
> > get_page_addr_code_hostp
> >        accel/tcg: Document the faulting lookup in tb_lookup_cmp
> >        accel/tcg: Remove translator_ldsw
> >        accel/tcg: Add pc and host_pc params to
> > gen_intermediate_code
> >        accel/tcg: Add fast path for translator_ld*
> >        target/riscv: Add MAX_INSN_LEN and insn_len
> >        target/riscv: Make translator stop before the end of a page
> 
>   Hi Richard!
> 
> Since your pull request has been merged, the Travis CI now constantly
> shows 
> a failure, see:
> 
>   https://app.travis-ci.com/gitlab/qemu-project/qemu/builds/255231855
> 
> The previous runs were all green, so I assume this has been
> introduced by 
> one of the patches in here. Could you please have a look?
> 
>   Thanks,
>    Thomas
> 

The reason seems to be that vstl instruction (used by libc's memcpy)
is not treated as a write for purposes of self-modifying-code
detection. This causes qemu to incorrectly forward SEGV to the guest
program.

I will prepare a patch.