5202861b20
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>
76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
/*
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* Semihosting support
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*
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* Copyright (c) 2015 Imagination Technologies
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef SEMIHOST_H
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#define SEMIHOST_H
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typedef enum SemihostingTarget {
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SEMIHOSTING_TARGET_AUTO = 0,
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SEMIHOSTING_TARGET_NATIVE,
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SEMIHOSTING_TARGET_GDB
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} SemihostingTarget;
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#ifdef CONFIG_USER_ONLY
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static inline bool semihosting_enabled(bool is_user)
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{
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return true;
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}
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static inline SemihostingTarget semihosting_get_target(void)
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{
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return SEMIHOSTING_TARGET_AUTO;
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}
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static inline const char *semihosting_get_arg(int i)
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{
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return NULL;
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}
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static inline int semihosting_get_argc(void)
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{
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return 0;
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}
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static inline const char *semihosting_get_cmdline(void)
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{
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return NULL;
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}
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#else /* !CONFIG_USER_ONLY */
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/**
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* semihosting_enabled:
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* @is_user: true if guest code is in usermode (i.e. not privileged)
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*
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* Return true if guest code is allowed to make semihosting calls.
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*/
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bool semihosting_enabled(bool is_user);
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SemihostingTarget semihosting_get_target(void);
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const char *semihosting_get_arg(int i);
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int semihosting_get_argc(void);
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const char *semihosting_get_cmdline(void);
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void semihosting_arg_fallback(const char *file, const char *cmd);
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/* for vl.c hooks */
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void qemu_semihosting_enable(void);
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int qemu_semihosting_config_options(const char *opt);
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void qemu_semihosting_chardev_init(void);
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void qemu_semihosting_console_init(Chardev *);
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#endif /* CONFIG_USER_ONLY */
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void qemu_semihosting_guestfd_init(void);
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#endif /* SEMIHOST_H */
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