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4e46c2a956
The UEFI spec revision 2.7 errata A section 8.4 has the following to say about the virtual memory runtime services: "This section contains function definitions for the virtual memory support that may be optionally used by an operating system at runtime. If an operating system chooses to make EFI runtime service calls in a virtual addressing mode instead of the flat physical mode, then the operating system must use the services in this section to switch the EFI runtime services from flat physical addressing to virtual addressing." So it is pretty clear that calling SetVirtualAddressMap() is entirely optional, and so there is no point in doing so unless it achieves anything useful for us. This is not the case for 64-bit ARM. The identity mapping used by the firmware is arbitrarily converted into another permutation of userland addresses (i.e., bits [63:48] cleared), and the runtime code could easily deal with the original layout in exactly the same way as it deals with the converted layout. However, due to constraints related to page size differences if the OS is not running with 4k pages, and related to systems that may expose the individual sections of PE/COFF runtime modules as different memory regions, creating the virtual layout is a bit fiddly, and requires us to sort the memory map and reason about adjacent regions with identical memory types etc etc. So the obvious fix is to stop calling SetVirtualAddressMap() altogether on arm64 systems. However, to avoid surprises, which are notoriously hard to diagnose when it comes to OS<->firmware interactions, let's start by making it an opt-out feature, and implement support for the 'efi=novamap' kernel command line parameter on ARM and arm64 systems. ( Note that 32-bit ARM generally does require SetVirtualAddressMap() to be used, given that the physical memory map and the kernel virtual address map are not guaranteed to be non-overlapping like on arm64. However, having support for efi=novamap,noruntime on 32-bit ARM, combined with the recently proposed support for earlycon=efifb, is likely to be useful to diagnose boot issues on such systems if they have no accessible serial port. ) Tested-by: Jeffrey Hugo <jhugo@codeaurora.org> Tested-by: Bjorn Andersson <bjorn.andersson@linaro.org> Tested-by: Lee Jones <lee.jones@linaro.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: AKASHI Takahiro <takahiro.akashi@linaro.org> Cc: Alexander Graf <agraf@suse.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de> Cc: Leif Lindholm <leif.lindholm@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Jones <pjones@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20190202094119.13230-8-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
79 lines
2.7 KiB
C
79 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _DRIVERS_FIRMWARE_EFI_EFISTUB_H
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#define _DRIVERS_FIRMWARE_EFI_EFISTUB_H
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/* error code which can't be mistaken for valid address */
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#define EFI_ERROR (~0UL)
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/*
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* __init annotations should not be used in the EFI stub, since the code is
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* either included in the decompressor (x86, ARM) where they have no effect,
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* or the whole stub is __init annotated at the section level (arm64), by
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* renaming the sections, in which case the __init annotation will be
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* redundant, and will result in section names like .init.init.text, and our
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* linker script does not expect that.
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*/
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#undef __init
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/*
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* Allow the platform to override the allocation granularity: this allows
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* systems that have the capability to run with a larger page size to deal
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* with the allocations for initrd and fdt more efficiently.
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*/
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#ifndef EFI_ALLOC_ALIGN
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#define EFI_ALLOC_ALIGN EFI_PAGE_SIZE
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#endif
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extern int __pure nokaslr(void);
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extern int __pure is_quiet(void);
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extern int __pure novamap(void);
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#define pr_efi(sys_table, msg) do { \
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if (!is_quiet()) efi_printk(sys_table, "EFI stub: "msg); \
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} while (0)
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#define pr_efi_err(sys_table, msg) efi_printk(sys_table, "EFI stub: ERROR: "msg)
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void efi_char16_printk(efi_system_table_t *, efi_char16_t *);
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unsigned long get_dram_base(efi_system_table_t *sys_table_arg);
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efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
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void *handle,
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unsigned long *new_fdt_addr,
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unsigned long max_addr,
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u64 initrd_addr, u64 initrd_size,
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char *cmdline_ptr,
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unsigned long fdt_addr,
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unsigned long fdt_size);
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void *get_fdt(efi_system_table_t *sys_table, unsigned long *fdt_size);
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void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
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unsigned long desc_size, efi_memory_desc_t *runtime_map,
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int *count);
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efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table,
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unsigned long size, u8 *out);
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efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
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unsigned long size, unsigned long align,
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unsigned long *addr, unsigned long random_seed);
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efi_status_t check_platform_features(efi_system_table_t *sys_table_arg);
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efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg);
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/* Helper macros for the usual case of using simple C variables: */
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#ifndef fdt_setprop_inplace_var
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#define fdt_setprop_inplace_var(fdt, node_offset, name, var) \
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fdt_setprop_inplace((fdt), (node_offset), (name), &(var), sizeof(var))
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#endif
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#ifndef fdt_setprop_var
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#define fdt_setprop_var(fdt, node_offset, name, var) \
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fdt_setprop((fdt), (node_offset), (name), &(var), sizeof(var))
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#endif
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#endif
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