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  1. Jan 07, 2021
  3. Dec 18, 2020
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    • Peter Maydell's avatar
      linux-user/sparc: Don't zero high half of PC, NPC, PSR in sigreturn · c3ab5df2
      Peter Maydell authored 
      
The function do_sigreturn() tries to store the PC, NPC and PSR in
uint32_t local variables, which implicitly drops the high half of
these fields for 64-bit guests.

The usual effect was that a guest which used signals would crash on
return from a signal unless it was lucky enough to take it while the
PC was in the low 4GB of the address space.  In particular, Debian
/bin/dash and /bin/bash would segfault after executing external
commands.

Use abi_ulong, which is the type these fields all have in the
__siginfo_t struct.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Message-Id: <20201105212314.9628-4-peter.maydell@linaro.org>
Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
      c3ab5df2
    • Peter Maydell's avatar
      linux-user/sparc: Correct set/get_context handling of fp and i7 · 266b4158
      Peter Maydell authored 
      
Because QEMU's user-mode emulation just directly accesses guest CPU
state, for SPARC the guest register window state is not the same in
the sparc64_get_context() and sparc64_set_context() functions as it
is for the real kernel's versions of those functions.  Specifically,
for the kernel it has saved the user space state such that the O*
registers go into a pt_regs struct as UREG_I*, and the I* registers
have been spilled onto the userspace stack.  For QEMU, we haven't
done that, so the guest's O* registers are still in WREG_O* and the
I* registers in WREG_I*.

The code was already accessing the O* registers correctly for QEMU,
but had copied the kernel code for accessing the I* registers off the
userspace stack.  Replace this with direct accesses to fp and i7 in
the CPU state, and add a comment explaining why we differ from the
kernel code here.

This fix is sufficient to get bash to a shell prompt.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Message-Id: <20201105212314.9628-3-peter.maydell@linaro.org>
Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
      266b4158
    • Peter Maydell's avatar
      linux-user/sparc: Fix errors in target_ucontext structures · b8ae597f
      Peter Maydell authored 
      
The various structs that make up the SPARC target_ucontext had some
errors:
 * target structures must not include fields which are host pointers,
   which might be the wrong size.  These should be abi_ulong instead
 * because we don't have the 'long double' part of the mcfpu_fregs
   union in our version of the target_mc_fpu struct, we need to
   manually force it to be 16-aligned

In particular, the lack of 16-alignment caused sparc64_get_context()
and sparc64_set_context() to read and write all the registers at the
wrong offset, which triggered a guest glibc stack check in
siglongjmp:
  *** longjmp causes uninitialized stack frame ***: terminated
when trying to run bash.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Message-Id: <20201105212314.9628-2-peter.maydell@linaro.org>
Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
      b8ae597f
  21. Nov 04, 2020
  23. Oct 27, 2020