[PATCH v3 2/3] arm: Add [U]EFI runtime services support
Grant Likely
grant.likely at linaro.org
Thu Dec 5 06:59:31 EST 2013
On Thu, 28 Nov 2013 16:41:22 +0000, Leif Lindholm <leif.lindholm at linaro.org> wrote:
> This patch implements basic support for UEFI runtime services in the
> ARM architecture - a requirement for using efibootmgr to read and update
> the system boot configuration.
>
> It uses the generic configuration table scanning to populate ACPI and
> SMBIOS pointers.
>
> Changes since v2:
> - Updated FDT bindings.
> - Preserve regions marked RESERVED (but don't map them).
> - Rename 'efi' -> 'uefi' within this new port (leaving core code as is).
>
> Signed-off-by: Leif Lindholm <leif.lindholm at linaro.org>
Hi Leif,
I've made a bunch of comments below. I've got concerns about the amount
of casting going on in this code, but the rest are pretty minor
Reviewed-by: Grant Likely <grant.likely at linaro.org>
> ---
> arch/arm/Kconfig | 15 ++
> arch/arm/include/asm/uefi.h | 22 ++
> arch/arm/kernel/Makefile | 2 +
> arch/arm/kernel/setup.c | 6 +
> arch/arm/kernel/uefi.c | 469 +++++++++++++++++++++++++++++++++++++++++++
> arch/arm/kernel/uefi_phys.S | 59 ++++++
> include/linux/efi.h | 2 +-
> 7 files changed, 574 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm/include/asm/uefi.h
> create mode 100644 arch/arm/kernel/uefi.c
> create mode 100644 arch/arm/kernel/uefi_phys.S
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 78a79a6a..db8d212 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1853,6 +1853,19 @@ config EARLY_IOREMAP
> the same virtual memory range as kmap so all early mappings must
> be unapped before paging_init() is called.
>
> +config EFI
> + bool "UEFI runtime service support"
> + depends on OF && !CPU_BIG_ENDIAN
> + select UCS2_STRING
> + select EARLY_IOREMAP
> + ---help---
> + This enables the kernel to use UEFI runtime services that are
> + available (such as the UEFI variable services).
> +
> + This option is only useful on systems that have UEFI firmware.
> + However, even with this option, the resultant kernel will
> + continue to boot on non-UEFI platforms.
> +
> config SECCOMP
> bool
> prompt "Enable seccomp to safely compute untrusted bytecode"
> @@ -2272,6 +2285,8 @@ source "net/Kconfig"
>
> source "drivers/Kconfig"
>
> +source "drivers/firmware/Kconfig"
> +
> source "fs/Kconfig"
>
> source "arch/arm/Kconfig.debug"
> diff --git a/arch/arm/include/asm/uefi.h b/arch/arm/include/asm/uefi.h
> new file mode 100644
> index 0000000..519ca18
> --- /dev/null
> +++ b/arch/arm/include/asm/uefi.h
> @@ -0,0 +1,22 @@
> +#ifndef _ASM_ARM_EFI_H
> +#define _ASM_ARM_EFI_H
> +
> +#include <asm/mach/map.h>
> +
> +extern int uefi_memblock_arm_reserve_range(void);
> +
> +typedef efi_status_t uefi_phys_call_t(u32 memory_map_size,
> + u32 descriptor_size,
> + u32 descriptor_version,
> + efi_memory_desc_t *dsc,
> + efi_set_virtual_address_map_t *f);
> +
> +extern efi_status_t uefi_phys_call(u32, u32, u32, efi_memory_desc_t *,
> + efi_set_virtual_address_map_t *);
> +
> +#define uefi_remap(cookie, size) __arm_ioremap((cookie), (size), MT_MEMORY)
> +#define uefi_ioremap(cookie, size) __arm_ioremap((cookie), (size), MT_DEVICE)
> +#define uefi_unmap(cookie) __arm_iounmap((cookie))
> +#define uefi_iounmap(cookie) __arm_iounmap((cookie))
> +
> +#endif /* _ASM_ARM_EFI_H */
> diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
> index a30fc9b..736cce4 100644
> --- a/arch/arm/kernel/Makefile
> +++ b/arch/arm/kernel/Makefile
> @@ -98,4 +98,6 @@ obj-y += psci.o
> obj-$(CONFIG_SMP) += psci_smp.o
> endif
>
> +obj-$(CONFIG_EFI) += uefi.o uefi_phys.o
> +
> extra-y := $(head-y) vmlinux.lds
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index 04c1757..9d44edd 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -30,6 +30,7 @@
> #include <linux/bug.h>
> #include <linux/compiler.h>
> #include <linux/sort.h>
> +#include <linux/efi.h>
>
> #include <asm/unified.h>
> #include <asm/cp15.h>
> @@ -57,6 +58,7 @@
> #include <asm/unwind.h>
> #include <asm/memblock.h>
> #include <asm/virt.h>
> +#include <asm/uefi.h>
>
> #include "atags.h"
>
> @@ -898,6 +900,10 @@ void __init setup_arch(char **cmdline_p)
> sanity_check_meminfo();
> arm_memblock_init(&meminfo, mdesc);
>
> +#ifdef CONFIG_EFI
> + uefi_memblock_arm_reserve_range();
> +#endif
> +
#ifdef block in code? You know better. :-) Make an empty stub in the
header files instead.
> paging_init(mdesc);
> request_standard_resources(mdesc);
>
> diff --git a/arch/arm/kernel/uefi.c b/arch/arm/kernel/uefi.c
> new file mode 100644
> index 0000000..f771026
> --- /dev/null
> +++ b/arch/arm/kernel/uefi.c
> @@ -0,0 +1,469 @@
> +/*
> + * Based on Unified Extensible Firmware Interface Specification version 2.3.1
> + *
> + * Copyright (C) 2013 Linaro Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/efi.h>
> +#include <linux/export.h>
> +#include <linux/memblock.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +
> +#include <asm/cacheflush.h>
> +#include <asm/idmap.h>
> +#include <asm/tlbflush.h>
> +#include <asm/uefi.h>
> +
> +struct efi_memory_map memmap;
> +
> +static efi_runtime_services_t *runtime;
> +
> +static phys_addr_t uefi_system_table;
> +static phys_addr_t uefi_boot_mmap;
> +static u32 uefi_boot_mmap_size;
> +static u32 uefi_mmap_desc_size;
> +static u32 uefi_mmap_desc_ver;
> +
> +static unsigned long arm_uefi_facility;
> +
> +/*
> + * If you're planning to wire up a debugger and debug the UEFI side ...
> + */
> +#undef KEEP_ALL_REGIONS
> +
> +/*
> + * If you need to (temporarily) support buggy firmware.
> + */
> +#define KEEP_BOOT_SERVICES_REGIONS
> +
> +/*
> + * Returns 1 if 'facility' is enabled, 0 otherwise.
> + */
> +int efi_enabled(int facility)
> +{
> + return test_bit(facility, &arm_uefi_facility) != 0;
> +}
> +EXPORT_SYMBOL(efi_enabled);
> +
> +static int uefi_debug __initdata;
> +static int __init uefi_debug_setup(char *str)
> +{
> + uefi_debug = 1;
> +
> + return 0;
> +}
> +early_param("uefi_debug", uefi_debug_setup);
> +
> +static struct {
> + const char *name;
> + const char *propname;
> + int numcells;
> + void *target;
> +} dt_params[] = {
> + {
> + "UEFI System Table", "linux,uefi-system-table",
> + 2, &uefi_system_table
> + }, {
> + "UEFI mmap address", "linux,uefi-mmap-start",
> + 2, &uefi_boot_mmap
> + }, {
> + "UEFI mmap size", "linux,uefi-mmap-size",
> + 1, &uefi_boot_mmap_size
> + }, {
> + "UEFI mmap descriptor size", "linux,uefi-mmap-desc-size",
> + 1, &uefi_mmap_desc_size
> + }, {
> + "UEFI mmap descriptor version", "linux,uefi-mmap-desc-ver",
> + 1, &uefi_mmap_desc_ver
> + }
> +};
> +
> +static int __init fdt_find_uefi_params(unsigned long node, const char *uname,
> + int depth, void *data)
> +{
> + void *prop;
> + int i;
> +
> + if (depth != 1 ||
> + (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen at 0") != 0))
> + return 0;
> +
> + pr_info("Getting UEFI parameters from FDT.\n");
> +
> + for (i = 0; i < sizeof(dt_params)/sizeof(*dt_params); i++) {
> + prop = of_get_flat_dt_prop(node, dt_params[i].propname, NULL);
> + if (!prop)
> + return 0;
> + if (dt_params[i].numcells == 1) {
> + u32 *target = dt_params[i].target;
> + *target = of_read_ulong(prop, 1);
> + } else {
> + u64 *target = dt_params[i].target;
> + *target = of_read_number(prop, 2);
> + }
> +
> + if (uefi_debug)
> + pr_info(" %s @ 0x%08x\n", dt_params[i].name,
> + *((u32 *)dt_params[i].target));
> + }
> +
> + return 1;
> +}
> +
> +static int __init uefi_init(void)
> +{
> + efi_char16_t *c16;
> + char vendor[100] = "unknown";
> + int i, retval;
> +
> + efi.systab = early_memremap(uefi_system_table,
> + sizeof(efi_system_table_t));
> +
> + /*
> + * Verify the UEFI System Table
> + */
> + if (efi.systab == NULL)
> + panic("Whoa! Can't find UEFI system table.\n");
> + if (efi.systab->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
> + panic("Whoa! UEFI system table signature incorrect\n");
Do you really want to panic here? The kernel may be able to continue
with the data in the DT. I would move these tests into
uefi_memblock_arm_reserve_range() and let it bail out doing nothing if
the tests fail (although it is good to print a warning).
> + if ((efi.systab->hdr.revision >> 16) == 0)
> + pr_warn("Warning: UEFI system table version %d.%02d, expected 1.00 or greater\n",
> + efi.systab->hdr.revision >> 16,
> + efi.systab->hdr.revision & 0xffff);
> +
> + /* Show what we know for posterity */
> + c16 = (efi_char16_t *)early_memremap(efi.systab->fw_vendor,
> + sizeof(vendor));
If you have to resort to a cast, then you're doing it wrong.
early_memremap() should already return a void*. Does that not work here?
> + if (c16) {
> + for (i = 0; i < (int) sizeof(vendor) - 1 && *c16; ++i)
> + vendor[i] = c16[i];
> + vendor[i] = '\0';
> + }
We need a better parser here, or at least filter out non-printable
characters. The best would be a conversion to UTF-8 I think (not that
we're doing that on the rest of UEFI code right now, so I would put this
as a followup item).
> +
> + pr_info("UEFI v%u.%.02u by %s\n",
> + efi.systab->hdr.revision >> 16,
> + efi.systab->hdr.revision & 0xffff, vendor);
> +
> + retval = efi_config_init(NULL);
> + if (retval == 0)
> + set_bit(EFI_CONFIG_TABLES, &arm_uefi_facility);
> +
> + early_iounmap(c16, sizeof(vendor));
> + early_iounmap(efi.systab, sizeof(efi_system_table_t));
> +
> + return retval;
> +}
> +
> +static __init int is_discardable_region(efi_memory_desc_t *md)
> +{
> +#ifdef KEEP_ALL_REGIONS
> + return 0;
> +#endif
> +
> + if (md->attribute & EFI_MEMORY_RUNTIME)
> + return 0;
> +
> + switch (md->type) {
> +#ifdef KEEP_BOOT_SERVICES_REGIONS
> + case EFI_BOOT_SERVICES_CODE:
> + case EFI_BOOT_SERVICES_DATA:
> +#endif
Having the #ifdef in code is gross. I would leave the block in place,
but make the return value configured by a #define value.
ie.
#define DISCARD_BOOT_SERVICES_REGIONS 1 /* Can be set to 0 */
...
case EFI_BOOT_SERVICES_CODE:
case EFI_BOOT_SERVICES_DATA:
return DISCARD_BOOT_SERVICES_REGIONS;
> + /* Keep tables around for any future kexec operations */
> + case EFI_ACPI_RECLAIM_MEMORY:
> + return 0;
> + /* Preserve */
> + case EFI_RESERVED_TYPE:
> + return 0;
> + }
> +
> + return 1;
> +}
> +
> +static __initdata struct {
> + u32 type;
> + const char *name;
> +} memory_type_name_map[] = {
> + {EFI_RESERVED_TYPE, "reserved"},
> + {EFI_LOADER_CODE, "loader code"},
> + {EFI_LOADER_DATA, "loader data"},
> + {EFI_BOOT_SERVICES_CODE, "boot services code"},
> + {EFI_BOOT_SERVICES_DATA, "boot services data"},
> + {EFI_RUNTIME_SERVICES_CODE, "runtime services code"},
> + {EFI_RUNTIME_SERVICES_DATA, "runtime services data"},
> + {EFI_CONVENTIONAL_MEMORY, "conventional memory"},
> + {EFI_UNUSABLE_MEMORY, "unusable memory"},
> + {EFI_ACPI_RECLAIM_MEMORY, "ACPI reclaim memory"},
> + {EFI_ACPI_MEMORY_NVS, "ACPI memory nvs"},
> + {EFI_MEMORY_MAPPED_IO, "memory mapped I/O"},
> + {EFI_MEMORY_MAPPED_IO_PORT_SPACE, "memory mapped I/O port space"},
> + {EFI_PAL_CODE, "pal code"},
> + {EFI_MAX_MEMORY_TYPE, NULL},
> +};
Can this be in common code?
> +
> +static __init void remove_sections(phys_addr_t addr, unsigned long size)
> +{
> + unsigned long section_offset;
> + unsigned long num_sections;
> +
> + section_offset = addr - (addr & SECTION_MASK);
> + num_sections = size / SECTION_SIZE;
> + if (size % SECTION_SIZE)
> + num_sections++;
> +
> + memblock_remove(addr - section_offset, num_sections * SECTION_SIZE);
> +}
> +
> +static __init int remove_regions(void)
> +{
> + efi_memory_desc_t *md;
> + int count = 0;
> + void *p, *e;
> +
> + if (uefi_debug)
> + pr_info("Processing UEFI memory map:\n");
> +
> + memmap.phys_map = early_memremap((phys_addr_t)(u32) uefi_boot_mmap,
> + uefi_boot_mmap_size);
Double casting? Why isn't only "(phys_addr_t)" sufficient? In fact,
uefi_boot_mmap is already phys_addr_t. Why is the cast needed at all?
> + if (!memmap.phys_map)
> + return 1;
> +
> + p = memmap.phys_map;
> + e = (void *)((u32)p + uefi_boot_mmap_size);
> + for (; p < e; p += uefi_mmap_desc_size) {
Again, the casting looks wrong. p is a void pointer. Adding
uefi_boot_mmap_size without casting should be just fine. I would do the
following to be more readable:
e = memmap.phys_map + uefi_boot_mmap_size;
for (p = memmap.phys_map; p < e; p += uefi_mmap_desc_size)
> + md = p;
> + if (is_discardable_region(md))
> + continue;
> +
> + if (uefi_debug)
> + pr_info(" %8llu pages @ %016llx (%s)\n",
> + md->num_pages, md->phys_addr,
> + memory_type_name_map[md->type].name);
> +
> + if (md->type != EFI_MEMORY_MAPPED_IO) {
> + remove_sections(md->phys_addr,
> + md->num_pages * PAGE_SIZE);
> + count++;
> + }
> + memmap.nr_map++;
> + }
> +
> + early_iounmap(memmap.phys_map, uefi_boot_mmap_size);
> +
> + if (uefi_debug)
> + pr_info("%d regions preserved.\n", memmap.nr_map);
> +
> + return 0;
> +}
> +
> +int __init uefi_memblock_arm_reserve_range(void)
> +{
> + if (!of_scan_flat_dt(fdt_find_uefi_params, NULL))
> + return 0;
> +
> + set_bit(EFI_BOOT, &arm_uefi_facility);
> +
> + uefi_init();
> +
> + remove_regions();
> +
> + return 0;
> +}
> +
> +/*
> + * Disable instrrupts, enable idmap and disable caches.
> + */
> +static void __init phys_call_prologue(void)
> +{
> + local_irq_disable();
> +
> + /* Take out a flat memory mapping. */
> + setup_mm_for_reboot();
> +
> + /* Clean and invalidate caches */
> + flush_cache_all();
> +
> + /* Turn off caching */
> + cpu_proc_fin();
> +
> + /* Push out any further dirty data, and ensure cache is empty */
> + flush_cache_all();
> +}
> +
> +/*
> + * Restore original memory map and re-enable interrupts.
> + */
> +static void __init phys_call_epilogue(void)
> +{
> + static struct mm_struct *mm = &init_mm;
> +
> + /* Restore original memory mapping */
> + cpu_switch_mm(mm->pgd, mm);
> +
> + /* Flush branch predictor and TLBs */
> + local_flush_bp_all();
> +#ifdef CONFIG_CPU_HAS_ASID
> + local_flush_tlb_all();
> +#endif
Empty stub please
> +
> + local_irq_enable();
> +}
> +
> +static int __init remap_region(efi_memory_desc_t *md, efi_memory_desc_t *entry)
> +{
> + u64 va;
> + u64 paddr;
> + u64 size;
> +
> + *entry = *md;
> + paddr = entry->phys_addr;
> + size = entry->num_pages << EFI_PAGE_SHIFT;
> +
> + /*
> + * Map everything writeback-capable as coherent memory,
> + * anything else as device.
> + */
> + if (md->attribute & EFI_MEMORY_WB)
> + va = (u64)((u32)uefi_remap(paddr, size) & 0xffffffffUL);
> + else
> + va = (u64)((u32)uefi_ioremap(paddr, size) & 0xffffffffUL);
Casting? Is it appropriate to throw away the upper 32 bits? On a large
memory system could that mean aliasing high regions into low?
> + if (!va)
> + return 0;
> + entry->virt_addr = va;
> +
> + if (uefi_debug)
> + pr_info(" %016llx-%016llx => 0x%08x : (%s)\n",
> + paddr, paddr + size - 1, (u32)va,
> + md->attribute & EFI_MEMORY_WB ? "WB" : "I/O");
> +
> + return 1;
> +}
> +
> +static int __init remap_regions(void)
> +{
> + void *p, *next;
> + efi_memory_desc_t *md;
> +
> + memmap.phys_map = uefi_remap(uefi_boot_mmap, uefi_boot_mmap_size);
> + if (!memmap.phys_map)
> + return 0;
> + memmap.map_end = (void *)memmap.phys_map + uefi_boot_mmap_size;
> + memmap.desc_size = uefi_mmap_desc_size;
> + memmap.desc_version = uefi_mmap_desc_ver;
> +
> + /* Allocate space for the physical region map */
> + memmap.map = kzalloc(memmap.nr_map * memmap.desc_size, GFP_KERNEL);
> + if (!memmap.map)
> + return 0;
> +
> + next = memmap.map;
> + for (p = memmap.phys_map; p < memmap.map_end; p += memmap.desc_size) {
> + md = p;
> + if (is_discardable_region(md) || md->type == EFI_RESERVED_TYPE)
> + continue;
> +
> + if (!remap_region(p, next))
> + return 0;
> +
> + next += memmap.desc_size;
> + }
> +
> + memmap.map_end = next;
> + efi.memmap = &memmap;
> +
> + uefi_unmap(memmap.phys_map);
> + memmap.phys_map = efi_lookup_mapped_addr(uefi_boot_mmap);
> + efi.systab = efi_lookup_mapped_addr(uefi_system_table);
> + if (efi.systab)
> + set_bit(EFI_SYSTEM_TABLES, &arm_uefi_facility);
> + /*
> + * efi.systab->runtime is a 32-bit pointer to something guaranteed by
> + * the UEFI specification to be 1:1 mapped in a 4GB address space.
> + */
> + runtime = efi_lookup_mapped_addr((u32)efi.systab->runtime);
> +
> + return 1;
> +}
> +
> +
> +/*
> + * This function switches the UEFI runtime services to virtual mode.
> + * This operation must be performed only once in the system's lifetime,
> + * including any kecec calls.
> + *
> + * This must be done with a 1:1 mapping. The current implementation
> + * resolves this by disabling the MMU.
> + */
> +efi_status_t __init phys_set_virtual_address_map(u32 memory_map_size,
> + u32 descriptor_size,
> + u32 descriptor_version,
> + efi_memory_desc_t *dsc)
> +{
> + uefi_phys_call_t *phys_set_map;
> + efi_status_t status;
> +
> + phys_call_prologue();
> +
> + phys_set_map = (void *)(unsigned long)virt_to_phys(uefi_phys_call);
> +
> + /* Called with caches disabled, returns with caches enabled */
> + status = phys_set_map(memory_map_size, descriptor_size,
> + descriptor_version, dsc,
> + efi.set_virtual_address_map)
> +;
> + phys_call_epilogue();
> +
> + return status;
> +}
> +
> +/*
> + * Called explicitly from init/mm.c
> + */
> +void __init efi_enter_virtual_mode(void)
> +{
> + efi_status_t status;
> +
> + if (!efi_enabled(EFI_BOOT)) {
> + pr_info("UEFI services will not be available.\n");
> + return;
> + }
> +
> + pr_info("Remapping and enabling UEFI services.\n");
> +
> + /* Map the regions we memblock_remove:d earlier into kernel
> + address space */
> + if (!remap_regions()) {
> + pr_info("Failed to remap UEFI regions - runtime services will not be available.\n");
> + return;
> + }
> +
> + /* Call SetVirtualAddressMap with the physical address of the map */
> + efi.set_virtual_address_map =
> + (efi_set_virtual_address_map_t *)
> + runtime->set_virtual_address_map;
I don't think the cast is necessary.
> + memmap.phys_map =
> + (efi_memory_desc_t *)(u32) __virt_to_phys((u32)memmap.map);
casting?
> +
> + status = phys_set_virtual_address_map(memmap.nr_map * memmap.desc_size,
> + memmap.desc_size,
> + memmap.desc_version,
> + memmap.phys_map);
> +
> + if (status != EFI_SUCCESS) {
> + pr_info("Failed to set UEFI virtual address map!\n");
> + return;
> + }
> +
> + /* Set up function pointers for efivars */
> + efi.get_variable = (efi_get_variable_t *)runtime->get_variable;
> + efi.get_next_variable =
> + (efi_get_next_variable_t *)runtime->get_next_variable;
> + efi.set_variable = (efi_set_variable_t *)runtime->set_variable;
> + set_bit(EFI_RUNTIME_SERVICES, &arm_uefi_facility);
ditto
> +}
> diff --git a/arch/arm/kernel/uefi_phys.S b/arch/arm/kernel/uefi_phys.S
> new file mode 100644
> index 0000000..e9a1542
> --- /dev/null
> +++ b/arch/arm/kernel/uefi_phys.S
> @@ -0,0 +1,59 @@
> +/*
> + * arch/arm/kernel/uefi_phys.S
> + *
> + * Copyright (C) 2013 Linaro Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/linkage.h>
> +#define PAR_MASK 0xfff
> +
> + .text
> +@ uefi_phys_call(a, b, c, d, *f)
> + .align 5
> + .pushsection .idmap.text, "ax"
> +ENTRY(uefi_phys_call)
> + @ Save physical context
> + mov r12, sp
> + push {r4-r5, r12, lr}
> +
> + @ Extract function pointer (don't write r12 beyond this)
> + ldr r12, [sp, #16]
> +
> + @ Convert sp to 32-bit physical
> + mov lr, sp
> + ldr r4, =PAR_MASK
> + and r5, lr, r4 @ Extract lower 12 bits of sp
> + mcr p15, 0, lr, c7, c8, 1 @ Write VA -> ATS1CPW
> + mrc p15, 0, lr, c7, c4, 0 @ Physical Address Register
> + mvn r4, r4
> + and lr, lr, r4 @ Clear lower 12 bits of PA
> + add lr, lr, r5 @ Calculate phys sp
> + mov sp, lr @ Update
> +
> + @ Disable MMU
> + mrc p15, 0, lr, c1, c0, 0 @ ctrl register
> + bic lr, lr, #0x1 @ ...............m
> + mcr p15, 0, lr, c1, c0, 0 @ disable MMU
> + isb
Nit: whitespace (tabs vs. spaces)
> +
> + @ Make call
> + blx r12
> +
> + pop {r4-r5, r12, lr}
> +
> + @ Enable MMU + Caches
> + mrc p15, 0, r1, c1, c0, 0 @ ctrl register
> + orr r1, r1, #0x1000 @ ...i............
> + orr r1, r1, #0x0005 @ .............c.m
> + mcr p15, 0, r1, c1, c0, 0 @ enable MMU
> + isb
Nit: whitespace
> +
> + @ Restore virtual sp and return
> + mov sp, r12
> + bx lr
> +ENDPROC(uefi_phys_call)
> + .popsection
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index bc5687d..ebb34ee 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -655,7 +655,7 @@ extern int __init efi_setup_pcdp_console(char *);
> #define EFI_64BIT 5 /* Is the firmware 64-bit? */
>
> #ifdef CONFIG_EFI
> -# ifdef CONFIG_X86
> +# if defined(CONFIG_X86) || defined(CONFIG_ARM)
ARM64 will need this too. Can we instead create a new empty config to
test here? CONFIG_EFI_ENABLED_ARCH perhaps?
g.
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