Commit Graph

68 Commits

Author SHA1 Message Date
Markus Armbruster 66997c42e0 cleanup: Tweak and re-run return_directly.cocci
Tweak the semantic patch to drop redundant parenthesis around the
return expression.

Coccinelle drops a comment in hw/rdma/vmw/pvrdma_cmd.c; restored
manually.

Coccinelle messes up vmdk_co_create(), not sure why.  Change dropped,
will be done manually in the next commit.

Line breaks in target/avr/cpu.h and hw/rdma/vmw/pvrdma_cmd.c tidied up
manually.

Whitespace in tools/virtiofsd/fuse_lowlevel.c tidied up manually.

checkpatch.pl complains "return of an errno should typically be -ve"
two times for hw/9pfs/9p-synth.c.  Preexisting, the patch merely makes
it visible to checkpatch.pl.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221122134917.1217307-2-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-12-14 16:19:35 +01:00
Bin Meng 3878d0c7d7 semihosting/arm-compat-semi: Avoid using hardcoded /tmp
Use g_get_tmp_dir() to get the directory to use for temporary files.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221006151927.2079583-2-bmeng.cn@gmail.com>
Message-Id: <20221027183637.2772968-11-alex.bennee@linaro.org>
2022-10-31 20:37:58 +00:00
Alex Bennée 424d5ecf52 semihosting: update link to spec
The old link has moved but it seems the document is now hosted on
Arm's github along with a license update to CC-BY-SA-4.0.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220929114231.583801-42-alex.bennee@linaro.org>
2022-10-06 11:53:41 +01:00
Peter Maydell 5202861b20 semihosting: Allow optional use of semihosting from userspace
Currently our semihosting implementations generally prohibit use of
semihosting calls in system emulation from the guest userspace.  This
is a very long standing behaviour justified originally "to provide
some semblance of security" (since code with access to the
semihosting ABI can do things like read and write arbitrary files on
the host system).  However, it is sometimes useful to be able to run
trusted guest code which performs semihosting calls from guest
userspace, notably for test code.  Add a command line suboption to
the existing semihosting-config option group so that you can
explicitly opt in to semihosting from guest userspace with
 -semihosting-config userspace=on

(There is no equivalent option for the user-mode emulator, because
there by definition all code runs in userspace and has access to
semihosting already.)

This commit adds the infrastructure for the command line option and
adds a bool 'is_user' parameter to the function
semihosting_userspace_enabled() that target code can use to check
whether it should be permitting the semihosting call for userspace.
It mechanically makes all the callsites pass 'false', so they
continue checking "is semihosting enabled in general".  Subsequent
commits will make each target that implements semihosting honour the
userspace=on option by passing the correct value and removing
whatever "don't do this for userspace" checking they were doing by
hand.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220822141230.3658237-2-peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-09-13 17:18:21 +01:00
Peter Maydell 9b1268f55c semihosting: Fix handling of buffer in TARGET_SYS_TMPNAM
The TARGET_SYS_TMPNAM implementation has two bugs spotted by
Coverity:
 * confusion about whether 'len' has the length of the string
   including or excluding the terminating NUL means we
   lock_user() len bytes of memory but memcpy() len + 1 bytes
 * In the error-exit cases we forget to free() the buffer
   that asprintf() returned to us

Resolves: Coverity CID 1490285, 1490289
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220719121110.225657-5-peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220725140520.515340-10-alex.bennee@linaro.org>
2022-07-29 09:48:01 +01:00
Peter Maydell fed49cdf6a semihosting: Check for errors on SET_ARG()
The SET_ARG() macro returns an error indication; we check this in the
TARGET_SYS_GET_CMDLINE case but not when we use it in implementing
TARGET_SYS_ELAPSED.  Check for and handle the errors via the do_fault
codepath, and update the comment documenting the SET_ARG() and
GET_ARG() macros to note how they handle memory access errors.

Resolves: Coverity CID 1490287
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220719121110.225657-4-peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220725140520.515340-9-alex.bennee@linaro.org>
2022-07-29 09:48:01 +01:00
Peter Maydell 45704e8904 semihosting: Don't copy buffer after console_write()
The console_write() semihosting function outputs guest data from a
buffer; it doesn't update that buffer.  It therefore doesn't need to
pass a length value to unlock_user(), but can pass 0, meaning "do not
copy any data back to the guest memory".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220719121110.225657-3-peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220725140520.515340-8-alex.bennee@linaro.org>
2022-07-29 09:48:01 +01:00
Peter Maydell aed04e6357 semihosting: Don't return negative values on qemu_semihosting_console_write() failure
The documentation comment for qemu_semihosting_console_write() says
 * Returns: number of bytes written -- this should only ever be short
 * on some sort of i/o error.

and the callsites rely on this.  However, the implementation code
path which sends console output to a chardev doesn't honour this,
and will return negative values on error.  Bring it into line with
the other implementation codepaths and the documentation, so that
it returns 0 on error.

Spotted by Coverity, because console_write() passes the return value
to unlock_user(), which doesn't accept a negative length.

Resolves: Coverity CID 1490288
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220719121110.225657-2-peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220725140520.515340-7-alex.bennee@linaro.org>
2022-07-29 09:48:01 +01:00
Richard Henderson 938fcd741a semihosting: Remove qemu_semihosting_log_out
The function is no longer used.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220628111701.677216-7-richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
2022-07-12 22:32:12 +02:00
Richard Henderson 1b9177f749 semihosting: Create semihost_sys_poll_one
This will be used for implementing the xtensa select_one
system call.  Choose "poll" over "select" so that we can
reuse Glib's g_poll constants and to avoid struct timeval.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:41:37 +05:30
Richard Henderson 2d010c2719 semihosting: Remove qemu_semihosting_console_outs
This function has been replaced by *_write.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:41:20 +05:30
Richard Henderson 7281550cfb semihosting: Use console_out_gf for SYS_WRITE0
Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:40:47 +05:30
Richard Henderson 004d2abe3f semihosting: Remove qemu_semihosting_console_outc
This function has been replaced by *_write.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:40:26 +05:30
Richard Henderson 5d77289dac semihosting: Use console_out_gf for SYS_WRITEC
Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:39:56 +05:30
Richard Henderson 1577eec0fc semihosting: Use console_in_gf for SYS_READC
Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:37:18 +05:30
Richard Henderson e4a4aaa51b semihosting: Create qemu_semihosting_guestfd_init
For arm-compat, initialize console_{in,out}_gf;
otherwise, initialize stdio file descriptors.

This will go some way to cleaning up arm-compat, and
will allow other semihosting to use normal stdio.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:36:50 +05:30
Richard Henderson 008e147572 semihosting: Add GuestFDConsole
Add a GuestFDType for connecting to the semihosting console.
Hook up to read, write, isatty, and fstat syscalls.

Note that the arm-specific syscall flen cannot be applied
to the console, because the console is not a descriptor
exposed to the guest.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:36:30 +05:30
Richard Henderson cd66f20f61 semihosting: Create qemu_semihosting_console_write
Will replace qemu_semihosting_console_{outs,outc},
but we need more plumbing first.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson fb08790b35 semihosting: Cleanup chardev init
Rename qemu_semihosting_connect_chardevs to
qemu_semihosting_chardev_init; pass the result
directly to qemu_semihosting_console_init.

Store the chardev in SemihostingConsole instead
of SemihostingConfig, which lets us drop
semihosting_get_chardev.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson e7fb6f3205 semihosting: Expand qemu_semihosting_console_inc to read
Allow more than one character to be read at one time.
Will be used by m68k and nios2 semihosting for stdio.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 3367d452b0 semihosting: Pass CPUState to qemu_semihosting_console_inc
We don't need CPUArchState, and we do want the CPUState of the
thread performing the operation -- use this instead of current_cpu.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 64c8c6a992 gdbstub: Adjust gdb_syscall_complete_cb declaration
Change 'ret' to uint64_t.  This resolves a FIXME in the
m68k and nios2 semihosting that we've lost data.
Change 'err' to int.  There is nothing target-specific
about the width of the errno value.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 1875dab0ee semihosting: Create semihost_sys_gettimeofday
This syscall will be used by m68k and nios2 semihosting.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson dffeb77566 semihosting: Create semihost_sys_{stat,fstat}
These syscalls will be used by m68k and nios2 semihosting.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 90d8e0b09c semihosting: Split out semihost_sys_system
Split out the non-ARM specific portions of SYS_SYSTEM to a
reusable function.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 25a95da0be semihosting: Split out semihost_sys_rename
Split out the non-ARM specific portions of SYS_RENAME to a
reusable function.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson d49e79b8e2 semihosting: Split out semihost_sys_remove
Split out the non-ARM specific portions of SYS_REMOVE to a
reusable function.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson a6300ed6b7 semihosting: Split out semihost_sys_flen
The ARM-specific SYS_FLEN isn't really something that can be
reused by other semihosting apis, but there are parts that can
reused for the implementation of semihost_sys_fstat.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson a221247430 semihosting: Split out semihost_sys_isatty
Split out the non-ARM specific portions of SYS_ISTTY to a
reusable function.  This handles all GuestFD.

Add a common_semi_istty_cb helper to translate the Posix
error return, 0+ENOTTY, to the Arm semihosting not-a-file
success result.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 9a89470449 semihosting: Split out semihost_sys_lseek
Split out the non-ARM specific portions of SYS_SEEK to a
reusable function.  This handles all GuestFD.  Isolate the
curious ARM-specific return value processing to a new
callback, common_semi_seek_cb.

Expand the internal type of the offset to int64_t, and
provide the whence argument, which will be required by
m68k and nios2 semihosting.

Note that gdb_do_syscall %x reads target_ulong, not int.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 40f1219a8b semihosting: Bound length for semihost_sys_{read,write}
Fixes a minor bug in which a 64-bit guest on a 32-bit host could
truncate the length.  This would only ever cause a problem if
there were no bits set in the low 32, so that it truncates to 0.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson aa915bd0a6 semihosting: Split out semihost_sys_write
Split out the non-ARM specific portions of SYS_WRITE to a
reusable function.  This handles all GuestFD.  This removes
the last use of common_semi_syscall_len.

Note that gdb_do_syscall %x reads target_ulong, not int.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson af0484b502 semihosting: Split out semihost_sys_read
Split out the non-ARM specific portions of SYS_READ to a
reusable function.  This handles all GuestFD.  Isolate the
curious ARM-specific return value processing to a new
callback, common_semi_rw_cb.

Note that gdb_do_syscall %x reads target_ulong, not int.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 5eadbbfca6 semihosting: Split out semihost_sys_close
Split out the non-ARM specific portions of SYS_CLOSE to a
reusable function.  This handles all GuestFD.

Note that gdb_do_syscall %x reads target_ulong, not int.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:52 +05:30
Richard Henderson 5b3f39cb04 semihosting: Split out semihost_sys_open
Split out the non-ARM specific portions of SYS_OPEN to a
reusable function.  This handles gdb and host file i/o.

Add helpers to validate the length of the filename string.
Prepare for usage by other semihosting by allowing the
filename length parameter to be 0, and calling strlen.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:39 +05:30
Richard Henderson 3753b00e57 semihosting: Move GET_ARG/SET_ARG earlier in the file
Moving this to be useful for another function
besides do_common_semihosting.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:27 +05:30
Richard Henderson 189878ae23 semihosting: Use env more often in do_common_semihosting
We've already loaded cs->env_ptr into a local variable; use it.
Since env is unconditionally used, we don't need a dummy use.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:27 +05:30
Richard Henderson 1b3b7693b7 semihosting: Split out common-semi-target.h
Move the ARM and RISCV specific helpers into
their own header file.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson a1df4bab43 semihosting: Split out common_semi_has_synccache
We already have some larger ifdef blocks for ARM and RISCV;
split out a boolean test for SYS_SYNCCACHE.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson 3c820ddc1b semihosting: Split common_semi_flen_buf per target
We already have some larger ifdef blocks for ARM and RISCV;
split out common_semi_stack_bottom per target.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson ef9c5ea85d semihosting: Split is_64bit_semihosting per target
We already have some larger ifdef blocks for ARM and RISCV;
split the function into multiple implementations per arch.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson cd7f29e335 semihosting: Use struct gdb_stat in common_semi_flen_cb
Load the entire 64-bit size value.  While we're at it,
use offsetof instead of an integer constant.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson 94b14fe08f include/exec: Move gdb open flags to gdbstub.h
There were 3 copies of these flags.  Place them in the
file with gdb_do_syscall, with which they belong.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson a1a2a3e609 semihosting: Remove GDB_O_BINARY
The value is zero, and gdb always opens files in binary mode.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson bb3b8821a3 semihosting: Move common-semi.h to include/semihosting/
This header is not private to the top-level semihosting directory,
so place it in the public include directory.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson ed3a06b10a semihosting: Return void from do_common_semihosting
Perform the cleanup in the FIXME comment in common_semi_gdb_syscall.
Do not modify guest registers until the syscall is complete,
which in the gdbstub case is asynchronous.

In the synchronous non-gdbstub case, use common_semi_set_ret
to set the result.  Merge set_swi_errno into common_semi_cb.
Rely on the latter for combined return value / errno setting.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson 4cfeff4ac1 semihosting: Clean up common_semi_open_cb
Use common_semi_cb to return results instead of calling
set_swi_errno and common_semi_set_ret directly.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson 84ca0dfd1e semihosting: Clean up common_semi_flen_cb
Do not read from the gdb struct stat buffer if the callback is
reporting an error. Use common_semi_cb to finish returning results.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson 709fe27b18 semihosting: Adjust error checking in common_semi_cb
The err parameter is non-zero if and only if an error occured.
Use this instead of ret == -1 for determining if we need to
update the saved errno.

This fixes the errno setting of SYS_ISTTY, which returns 0 on
error, not -1.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30
Richard Henderson 5aadd18299 semihosting: Inline set_swi_errno into common_semi_cb
Do not store 'err' into errno only to read it back immediately.
Use 'ret' for the return value, not 'reg0'.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2022-06-28 04:35:07 +05:30