The exception return address for nios2 is the instruction
after the one that was executing at the time of the exception.
We have so far implemented this by advancing the pc during the
process of raising the exception. It is perhaps a little less
confusing to do this advance in the translator (and helpers)
when raising the exception in the first place, so that we may
more closely match kernel sources.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220421151735.31996-58-richard.henderson@linaro.org>
Indirect branches, plus eret and bret optionally raise
an exception when branching to a misaligned address.
The exception is required when an mmu is enabled, but
enable it always because the fallback behaviour is not
documented (though presumably it discards low bits).
For the purposes of the linux-user cpu loop, if EXCP_UNALIGN
(misaligned data) were to arrive, it would be treated the
same as EXCP_UNALIGND (misaligned destination). See the
!defined(CONFIG_NIOS2_ALIGNMENT_TRAP) block in kernel/traps.c.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-53-richard.henderson@linaro.org>
Drop the set of estatus in init_thread; it was clearly intended
to be setting the value of CR_STATUS for the application, but we
never actually performed that copy. However, the proper value is
set in nios2_cpu_reset so we don't need to do anything here.
We only initialize SP and EA in init_thread, there's no value in
copying other uninitialized data into ENV.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-21-richard.henderson@linaro.org>
Note that this advance *should* be done by the translator, as
that's the pc value that's supposed to be generated by hardware.
However, that's a much larger change across sysemu as well.
In the meantime, produce the correct PC for any signals raised
by the trap instruction. Note the special case of TRAP_BRKPT,
which itself is special cased within the kernel.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-2-richard.henderson@linaro.org>
The real kernel will talk about the user PC as EA,
because that's where the hardware will have copied it,
and where it expects to put it to then use ERET.
But qemu does not emulate all of the exception stuff
while emulating user-only. Manipulate PC directly.
This fixes signal entry and return, and eliminates
some slight confusion from target_cpu_copy_regs.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20211221025012.1057923-6-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
qemu.h is included in various non-linux-user files (which
mostly want the TaskState struct and the functions for
doing usermode access to guest addresses like lock_user(),
unlock_user(), get_user*(), etc).
Split out the parts that are only used in linux-user itself
into a new user-internals.h. This leaves qemu.h with basically
three things:
* the definition of the TaskState struct
* the user-access functions and macros
* do_brk()
all of which are needed by code outside linux-user that
includes qemu.h.
The addition of all the extra #include lines was done with
sed -i '/include.*qemu\.h/a #include "user-internals.h"' $(git grep -l 'include.*qemu\.h' linux-user)
(and then undoing the change to fpa11.h).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210908154405.15417-8-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Nios II user-mode emulation was missing handling for EXCP_DEBUG,
making the gdb stub essentially useless. This patch adds the missing
piece. The new code was copied from the existing EXCP_TRAP handling
and is also similar to what other targets (e.g., arm) do with EXCP_DEBUG.
Signed-off-by: Sandra Loosemore <sandra@codesourcery.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <1550076626-7202-1-git-send-email-sandra@codesourcery.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
The nios2 main loop code's code does some odd
things with gdb_handlesig() that no other target
CPU does: it has some signals that are delivered
to gdb and only to gdb. Stop doing this, and instead
behave like all the other targets:
* a trap instruction becomes a SIGTRAP
* an unhandled exception type returned from cpu_exec()
causes us to abort(), not to try to hand gdb a SIGILL
This fixes in passing Coverity issue CID 1390853,
which was a complaint that the old code failed to
check the return value from gdb_handlesig().
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20181019174958.26616-3-peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[lv: removed gdbsig unused variable]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Create a cpu_loop-common.h for future use by
these new files and use it in the existing
main.c
Introduce target_cpu_copy_regs():
declare the function in cpu_loop-common.h
and an empty function for each target,
to move all the cpu_loop prologues to this function.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20180411185651.21351-2-laurent@vivier.eu>
