jcs.org
qemu with hax to log dma reads & writes
jcs.org/2018/11/12/vfio
semihosting: implement a semihosting console
This provides two functions for handling console output that handle
the common backend behaviour for semihosting.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
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hw/semihosting/Makefile.objs
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hw/semihosting/Makefile.objs
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hw/semihosting/console.c
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hw/semihosting/console.c
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/*
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* Semihosting Console Support
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*
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* Copyright (c) 2015 Imagination Technologies
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* Copyright (c) 2019 Linaro Ltd
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*
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* This provides support for outputting to a semihosting console.
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*
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* While most semihosting implementations support reading and writing
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* to arbitrary file descriptors we treat the console as something
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* specifically for debugging interaction. This means messages can be
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* re-directed to gdb (if currently being used to debug) or even
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* re-directed elsewhere.
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "qemu/osdep.h"
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#include "cpu.h"
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#include "hw/semihosting/console.h"
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#include "exec/gdbstub.h"
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#include "qemu/log.h"
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int qemu_semihosting_log_out(const char *s, int len)
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{
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return write(STDERR_FILENO, s, len);
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}
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/*
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* A re-implementation of lock_user_string that we can use locally
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* instead of relying on softmmu-semi. Hopefully we can deprecate that
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* in time. We either copy len bytes if specified or until we find a NULL.
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*/
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static GString *copy_user_string(CPUArchState *env, target_ulong addr, int len)
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{
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CPUState *cpu = ENV_GET_CPU(env);
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GString *s = g_string_sized_new(len ? len : 128);
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uint8_t c;
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bool done;
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do {
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if (cpu_memory_rw_debug(cpu, addr++, &c, 1, 0) == 0) {
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s = g_string_append_c(s, c);
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done = len ? s->len == len : c == 0;
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} else {
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qemu_log_mask(LOG_GUEST_ERROR,
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"%s: passed inaccessible address " TARGET_FMT_lx,
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__func__, addr);
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done = true;
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}
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} while (!done);
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return s;
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}
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static void semihosting_cb(CPUState *cs, target_ulong ret, target_ulong err)
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{
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if (ret == (target_ulong) -1) {
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qemu_log("%s: gdb console output failed ("TARGET_FMT_ld")",
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__func__, err);
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}
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}
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int qemu_semihosting_console_out(CPUArchState *env, target_ulong addr, int len)
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{
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GString *s = copy_user_string(env, addr, len);
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int out = s->len;
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if (use_gdb_syscalls()) {
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gdb_do_syscall(semihosting_cb, "write,2,%x,%x", addr, s->len);
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} else {
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out = qemu_semihosting_log_out(s->str, s->len);
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}
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g_string_free(s, true);
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return out;
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}
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include/hw/semihosting/console.h
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include/hw/semihosting/console.h
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/*
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* Semihosting Console
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*
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* Copyright (c) 2019 Linaro Ltd
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#ifndef _SEMIHOST_CONSOLE_H_
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#define _SEMIHOST_CONSOLE_H_
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/**
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* qemu_semihosting_console_out:
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* @env: CPUArchState
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* @s: host address of guest string
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* @len: length of string or 0 (string is null terminated)
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*
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* Send a guest string to the debug console. This may be the remote
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* gdb session if a softmmu guest is currently being debugged.
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*
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* Returns: number of bytes written.
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*/
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int qemu_semihosting_console_out(CPUArchState *env, target_ulong s, int len);
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/**
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* qemu_semihosting_log_out:
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* @s: pointer to string
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* @len: length of string
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*
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* Send a string to the debug output. Unlike console_out these strings
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* can't be sent to a remote gdb instance as they don't exist in guest
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* memory.
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*
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* Returns: number of bytes written
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*/
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int qemu_semihosting_log_out(const char *s, int len);
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#endif /* _SEMIHOST_CONSOLE_H_ */