qemu/target/nios2
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
..
cpu-param.h Normalize header guard symbol definition 2022-05-11 16:50:26 +02:00
cpu.c target/nios2: Implement EIC interrupt processing 2022-04-26 08:17:05 -07:00
cpu.h target/nios2: Advance pc when raising exceptions 2022-04-26 08:17:05 -07:00
helper.c target/nios2: Advance pc when raising exceptions 2022-04-26 08:17:05 -07:00
helper.h target/nios2: Implement rdprs, wrprs 2022-04-26 08:17:05 -07:00
Kconfig meson: Introduce target-specific Kconfig 2021-07-09 18:21:34 +02:00
meson.build target/nios2: Move nios2-semi.c to nios2_softmmu_ss 2022-06-28 10:18:57 +05:30
mmu.c target/nios2: Use hw/registerfields.h for CR_TLBMISC fields 2022-04-26 08:16:41 -07:00
mmu.h target: Include missing 'cpu.h' 2022-03-06 13:15:42 +01:00
monitor.c hmp: Pass monitor to mon_get_cpu_env() 2020-11-13 12:45:51 +00:00
nios2-semi.c target/nios2: Convert semihosting errno to gdb remote errno 2022-09-13 17:18:20 +01:00
op_helper.c target/nios2: Advance pc when raising exceptions 2022-04-26 08:17:05 -07:00
trace-events target/nios2: Replace MMU_LOG with tracepoints 2022-03-03 09:36:38 -10:00
translate.c semihosting: Allow optional use of semihosting from userspace 2022-09-13 17:18:21 +01:00