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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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83e6818974
Originally 'efi_enabled' indicated whether a kernel was booted from
EFI firmware. Over time its semantics have changed, and it now
indicates whether or not we are booted on an EFI machine with
bit-native firmware, e.g. 64-bit kernel with 64-bit firmware.
The immediate motivation for this patch is the bug report at,
https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557
which details how running a platform driver on an EFI machine that is
designed to run under BIOS can cause the machine to become
bricked. Also, the following report,
https://bugzilla.kernel.org/show_bug.cgi?id=47121
details how running said driver can also cause Machine Check
Exceptions. Drivers need a new means of detecting whether they're
running on an EFI machine, as sadly the expression,
if (!efi_enabled)
hasn't been a sufficient condition for quite some time.
Users actually want to query 'efi_enabled' for different reasons -
what they really want access to is the list of available EFI
facilities.
For instance, the x86 reboot code needs to know whether it can invoke
the ResetSystem() function provided by the EFI runtime services, while
the ACPI OSL code wants to know whether the EFI config tables were
mapped successfully. There are also checks in some of the platform
driver code to simply see if they're running on an EFI machine (which
would make it a bad idea to do BIOS-y things).
This patch is a prereq for the samsung-laptop fix patch.
Cc: David Airlie <airlied@linux.ie>
Cc: Corentin Chary <corentincj@iksaif.net>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Peter Jones <pjones@redhat.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Steve Langasek <steve.langasek@canonical.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad@kernel.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
113 lines
2.8 KiB
C
113 lines
2.8 KiB
C
/*
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* Copyright 2007-2010 Red Hat, Inc.
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* by Peter Jones <pjones@redhat.com>
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* Copyright 2007 IBM, Inc.
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* by Konrad Rzeszutek <konradr@linux.vnet.ibm.com>
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* Copyright 2008
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* by Konrad Rzeszutek <ketuzsezr@darnok.org>
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*
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* This code finds the iSCSI Boot Format Table.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License v2.0 as published by
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* the Free Software Foundation
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*
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* This program 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
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* GNU General Public License for more details.
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*/
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#include <linux/bootmem.h>
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#include <linux/blkdev.h>
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#include <linux/ctype.h>
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#include <linux/device.h>
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#include <linux/efi.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/limits.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/stat.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/acpi.h>
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#include <linux/iscsi_ibft.h>
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#include <asm/mmzone.h>
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/*
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* Physical location of iSCSI Boot Format Table.
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*/
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struct acpi_table_ibft *ibft_addr;
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EXPORT_SYMBOL_GPL(ibft_addr);
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static const struct {
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char *sign;
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} ibft_signs[] = {
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{ "iBFT" },
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{ "BIFT" }, /* Broadcom iSCSI Offload */
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};
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#define IBFT_SIGN_LEN 4
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#define IBFT_START 0x80000 /* 512kB */
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#define IBFT_END 0x100000 /* 1MB */
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#define VGA_MEM 0xA0000 /* VGA buffer */
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#define VGA_SIZE 0x20000 /* 128kB */
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static int __init find_ibft_in_mem(void)
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{
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unsigned long pos;
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unsigned int len = 0;
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void *virt;
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int i;
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for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
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/* The table can't be inside the VGA BIOS reserved space,
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* so skip that area */
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if (pos == VGA_MEM)
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pos += VGA_SIZE;
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virt = isa_bus_to_virt(pos);
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for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
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if (memcmp(virt, ibft_signs[i].sign, IBFT_SIGN_LEN) ==
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0) {
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unsigned long *addr =
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(unsigned long *)isa_bus_to_virt(pos + 4);
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len = *addr;
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/* if the length of the table extends past 1M,
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* the table cannot be valid. */
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if (pos + len <= (IBFT_END-1)) {
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ibft_addr = (struct acpi_table_ibft *)virt;
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pr_info("iBFT found at 0x%lx.\n", pos);
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goto done;
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}
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}
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}
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}
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done:
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return len;
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}
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/*
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* Routine used to find the iSCSI Boot Format Table. The logical
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* kernel address is set in the ibft_addr global variable.
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*/
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unsigned long __init find_ibft_region(unsigned long *sizep)
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{
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ibft_addr = NULL;
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/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
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* only use ACPI for this */
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if (!efi_enabled(EFI_BOOT))
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find_ibft_in_mem();
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if (ibft_addr) {
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*sizep = PAGE_ALIGN(ibft_addr->header.length);
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return (u64)isa_virt_to_bus(ibft_addr);
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}
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*sizep = 0;
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return 0;
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}
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