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[176.184.0.172]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-57cae785da2sm415854a12.13.2024.06.12.06.12.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Jun 2024 06:12:51 -0700 (PDT) Message-ID: <5c913504-d917-4fd1-86d5-85d3bc293623@linaro.org> Date: Wed, 12 Jun 2024 15:12:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/3] semihosting: Restrict to TCG From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= To: Paolo Bonzini Cc: qemu-devel@nongnu.org, =?UTF-8?Q?Alex_Benn=C3=A9e?= , Anton Johansson References: <20240529155548.5878-1-philmd@linaro.org> <20240529155548.5878-4-philmd@linaro.org> <7ce86375-779d-43d6-9871-7f9587c95ba6@linaro.org> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::62f; envelope-from=philmd@linaro.org; helo=mail-ej1-x62f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Paolo, On 30/5/24 15:58, Philippe Mathieu-Daudé wrote: > On 30/5/24 09:31, Paolo Bonzini wrote: >> On Thu, May 30, 2024 at 9:22 AM Philippe Mathieu-Daudé >> wrote: >>> >>> On 30/5/24 08:02, Paolo Bonzini wrote: >>>> On Wed, May 29, 2024 at 5:56 PM Philippe Mathieu-Daudé >>>> wrote: >>>>> It is pointless to build semihosting when TCG is not available. >>>> >>>> Why? I would have naively assumed that a suitable semihosting API >>>> could be implemented by KVM. The justification (and thus the commit >>>> message) needs to be different for each architecture if it's a matter >>>> of instruction set or insufficient KVM userspace API. >>> >>> I wasn't sure where semihosting could be used so asked on IRC and >>> Alex told me TCG only. Maybe the current implementation is TCG >>> only, and I can reword. It certainly need some refactor to work >>> on KVM, because currently semihosting end calling the TCG probe_access >>> API, which I'm trying to restrict to TCG in order to ease linking >>> multiple libtcg for the single binary (see >>> https://lore.kernel.org/qemu-devel/20240529155918.6221-1-philmd@linaro.org/). >> >> Ok, that goes in the commit message though. >> >> "Semihosting currently uses the TCG probe_access API. It is pointless >> to have it in the binary when TCG isn't". >> >> and in the first two patches: >> >> "Semihosting currently uses the TCG probe_access API. To prepare for >> encoding the TCG dependency in Kconfig, do not enable it unless TCG is >> available". >> >> But then, "select FOO if TCG" mean that it can be compiled out; so >> perhaps "imply SEMIHOSTING if TCG" is better? Same for RISC-V's >> "select ARM_COMPATIBLE_SEMIHOSTING if TCG". Building qemu-system-mips configured with --without-default-devices: Undefined symbols for architecture arm64: "_qemu_semihosting_console_write", referenced from: _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o "_semihost_sys_close", referenced from: _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o "_uaccess_strlen_user", referenced from: _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o ... So this one has to use "select". Similarly m68k: Undefined symbols for architecture arm64: "_semihost_sys_close", referenced from: _do_m68k_semihosting in target_m68k_m68k-semi.c.o ... I can link m68k using semihosting stubs but I'm not sure it is right: -- >8 -- diff --git a/semihosting/stubs-target-all.c b/semihosting/stubs-target-all.c new file mode 100644 index 0000000000..1f33173f43 --- /dev/null +++ b/semihosting/stubs-target-all.c @@ -0,0 +1,97 @@ +/* + * Semihosting Stubs + * + * Copyright (c) 2024 Linaro Ltd + * + * Stubs for semihosting targets that don't actually do semihosting. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#include "qemu/osdep.h" +#include "exec/exec-all.h" +#include "semihosting/syscalls.h" + +void semihost_sys_open(CPUState *cs, gdb_syscall_complete_cb complete, + target_ulong fname, target_ulong fname_len, + int gdb_flags, int mode) +{ +} + +void semihost_sys_close(CPUState *cs, gdb_syscall_complete_cb complete, int fd) +{ +} + +void semihost_sys_read_gf(CPUState *cs, gdb_syscall_complete_cb complete, + GuestFD *gf, target_ulong buf, target_ulong len) +{ +} + +void semihost_sys_read(CPUState *cs, gdb_syscall_complete_cb complete, + int fd, target_ulong buf, target_ulong len) +{ +} + +void semihost_sys_write_gf(CPUState *cs, gdb_syscall_complete_cb complete, + GuestFD *gf, target_ulong buf, target_ulong len) +{ +} + +void semihost_sys_write(CPUState *cs, gdb_syscall_complete_cb complete, + int fd, target_ulong buf, target_ulong len) +{ +} + +void semihost_sys_lseek(CPUState *cs, gdb_syscall_complete_cb complete, + int fd, int64_t off, int gdb_whence) +{ +} + +void semihost_sys_isatty(CPUState *cs, gdb_syscall_complete_cb complete, int fd) +{ +} + +void semihost_sys_flen(CPUState *cs, gdb_syscall_complete_cb fstat_cb, + gdb_syscall_complete_cb flen_cb, int fd, + target_ulong fstat_addr) +{ +} + +void semihost_sys_fstat(CPUState *cs, gdb_syscall_complete_cb complete, + int fd, target_ulong addr) +{ +} + +void semihost_sys_stat(CPUState *cs, gdb_syscall_complete_cb complete, + target_ulong fname, target_ulong fname_len, + target_ulong addr) +{ +} + +void semihost_sys_remove(CPUState *cs, gdb_syscall_complete_cb complete, + target_ulong fname, target_ulong fname_len) +{ +} + +void semihost_sys_rename(CPUState *cs, gdb_syscall_complete_cb complete, + target_ulong oname, target_ulong oname_len, + target_ulong nname, target_ulong nname_len) +{ +} + +void semihost_sys_system(CPUState *cs, gdb_syscall_complete_cb complete, + target_ulong cmd, target_ulong cmd_len) +{ +} + +void semihost_sys_gettimeofday(CPUState *cs, gdb_syscall_complete_cb complete, + target_ulong tv_addr, target_ulong tz_addr) +{ +} + +#ifndef CONFIG_USER_ONLY +void semihost_sys_poll_one(CPUState *cs, gdb_syscall_complete_cb complete, + int fd, GIOCondition cond, int timeout) +{ +} +#endif diff --git a/semihosting/meson.build b/semihosting/meson.build index 34933e5a19..aa8b7a9913 100644 --- a/semihosting/meson.build +++ b/semihosting/meson.build @@ -7,7 +7,7 @@ specific_ss.add(when: ['CONFIG_SEMIHOSTING', 'CONFIG_SYSTEM_ONLY'], if_true: fil 'config.c', 'console.c', 'uaccess.c', -)) +), if_false: files('stubs-target-all.c')) common_ss.add(when: ['CONFIG_SEMIHOSTING', 'CONFIG_SYSTEM_ONLY'], if_false: files('stubs-all.c')) system_ss.add(when: ['CONFIG_SEMIHOSTING'], if_false: files('stubs-system.c')) --- For mips more stubs are needed: Undefined symbols for architecture arm64: "_qemu_semihosting_console_write", referenced from: _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o "_uaccess_lock_user", referenced from: _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _uhi_fstat_cb in target_mips_tcg_sysemu_mips-semi.c.o "_uaccess_lock_user_string", referenced from: _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting.cold.6 in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting.cold.6 in target_mips_tcg_sysemu_mips-semi.c.o "_uaccess_strlen_user", referenced from: _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o "_uaccess_unlock_user", referenced from: _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _mips_semihosting in target_mips_tcg_sysemu_mips-semi.c.o _uhi_fstat_cb in target_mips_tcg_sysemu_mips-semi.c.o ...