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lib/i386-io-linux.h
77 строк
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Pali Rohár
lib: Refactor access to x86 I/O ports
30 дек 2023, 18:26
30 дек 2023, 18:26
cf930fa
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/* * The PCI Library -- Access to i386 I/O ports on Linux * * Copyright (c) 1997--2006 Martin Mares <mj@ucw.cz> * * Can be freely distributed and used under the terms of the GNU GPL v2+ * * SPDX-License-Identifier: GPL-2.0-or-later */ #include <sys/io.h> #include <errno.h> #include "i386-io-access.h" static int ioperm_enabled; static int iopl_enabled; static int intel_setup_io(struct pci_access *a UNUSED) { if (ioperm_enabled || iopl_enabled) return 1; /* * Before Linux 2.6.8, only the first 0x3ff I/O ports permissions can be * modified via ioperm(). Since 2.6.8 all ports are supported. * Since Linux 5.5, EFLAGS-based iopl() implementation was removed and * replaced by new TSS-IOPB-map-all-based emulator. Before Linux 5.5, * EFLAGS-based iopl() allowed userspace to enable/disable interrupts, * which is dangerous. So prefer usage of ioperm() and fallback to iopl(). */ if (ioperm(0xcf8, 8, 1) < 0) /* conf1 + conf2 ports */ { if (errno == EINVAL) /* ioperm() unsupported */ { if (iopl(3) < 0) return 0; iopl_enabled = 1; return 1; } return 0; } if (ioperm(0xc000, 0xfff, 1) < 0) /* remaining conf2 ports */ { ioperm(0xcf8, 8, 0); return 0; } ioperm_enabled = 1; return 1; } static inline void intel_cleanup_io(struct pci_access *a UNUSED) { if (ioperm_enabled) { ioperm(0xcf8, 8, 0); ioperm(0xc000, 0xfff, 0); ioperm_enabled = 0; } if (iopl_enabled) { iopl(0); iopl_enabled = 0; } } static inline void intel_io_lock(void) { } static inline void intel_io_unlock(void) { }