[RFT PATCH v4 8/9] RISC-V: Add EFI runtime services

Atish Patra
2020-07-29T23:37:05Z

This patch adds EFI runtime service support for RISC-V.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
arch/riscv/Kconfig | 2 +
arch/riscv/include/asm/efi.h | 20 ++++
arch/riscv/include/asm/mmu.h | 2 +
arch/riscv/include/asm/pgtable.h | 4 +
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/efi.c | 105 +++++++++++++++++
arch/riscv/kernel/setup.c | 7 +-
arch/riscv/mm/init.c | 2 +-
drivers/firmware/efi/Makefile | 2 +
drivers/firmware/efi/libstub/efi-stub.c | 11 +-
drivers/firmware/efi/riscv-runtime.c | 143 ++++++++++++++++++++++++
11 files changed, 295 insertions(+), 4 deletions(-)
create mode 100644 arch/riscv/kernel/efi.c
create mode 100644 drivers/firmware/efi/riscv-runtime.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a6569c268565..4858b19fe3a4 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -401,7 +401,9 @@ config EFI
select EFI_PARAMS_FROM_FDT
select EFI_STUB
select EFI_GENERIC_STUB
+ select EFI_RUNTIME_WRAPPERS
select RISCV_ISA_C
+ depends on MMU
default y
help
This option provides support for runtime services provided
diff --git a/arch/riscv/include/asm/efi.h b/arch/riscv/include/asm/efi.h
index 86da231909bb..93c305a638f4 100644
--- a/arch/riscv/include/asm/efi.h
+++ b/arch/riscv/include/asm/efi.h
@@ -5,11 +5,28 @@
#ifndef _ASM_EFI_H
#define _ASM_EFI_H

+#include <asm/csr.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/ptrace.h>
#include <asm/tlbflush.h>

+#ifdef CONFIG_EFI
+extern void efi_init(void);
+#else
+#define efi_init()
+#endif
+
+int efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md);
+int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
+
+#define arch_efi_call_virt_setup() efi_virtmap_load()
+#define arch_efi_call_virt_teardown() efi_virtmap_unload()
+
+#define arch_efi_call_virt(p, f, args...) p->f(args)
+
+#define ARCH_EFI_IRQ_FLAGS_MASK (SR_IE | SR_SPIE)
+
/* on RISC-V, the FDT may be located anywhere in system RAM */
static inline unsigned long efi_get_max_fdt_addr(unsigned long dram_base)
{
@@ -33,4 +50,7 @@ static inline void efifb_setup_from_dmi(struct screen_info *si, const char *opt)
{
}

+void efi_virtmap_load(void);
+void efi_virtmap_unload(void);
+
#endif /* _ASM_EFI_H */
diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
index 967eacb01ab5..dabcf2cfb3dc 100644
--- a/arch/riscv/include/asm/mmu.h
+++ b/arch/riscv/include/asm/mmu.h
@@ -20,6 +20,8 @@ typedef struct {
#endif
} mm_context_t;

+void __init create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t pa,
+ phys_addr_t sz, pgprot_t prot);
#endif /* __ASSEMBLY__ */

#endif /* _ASM_RISCV_MMU_H */
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 815f8c959dd4..183f1f4b2ae6 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -100,6 +100,10 @@

#define PAGE_KERNEL __pgprot(_PAGE_KERNEL)
#define PAGE_KERNEL_EXEC __pgprot(_PAGE_KERNEL | _PAGE_EXEC)
+#define PAGE_KERNEL_READ __pgprot(_PAGE_KERNEL & ~_PAGE_WRITE)
+#define PAGE_KERNEL_EXEC __pgprot(_PAGE_KERNEL | _PAGE_EXEC)
+#define PAGE_KERNEL_READ_EXEC __pgprot((_PAGE_KERNEL & ~_PAGE_WRITE) \
+ | _PAGE_EXEC)

#define PAGE_TABLE __pgprot(_PAGE_TABLE)

diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 6f7a3b3771fd..239c44c451b6 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -36,6 +36,7 @@ OBJCOPYFLAGS := --prefix-symbols=__efistub_
$(obj)/%.stub.o: $(obj)/%.o FORCE
$(call if_changed,objcopy)

+obj-$(CONFIG_EFI) += efi.o
obj-$(CONFIG_FPU) += fpu.o
obj-$(CONFIG_SMP) += smpboot.o
obj-$(CONFIG_SMP) += smp.o
diff --git a/arch/riscv/kernel/efi.c b/arch/riscv/kernel/efi.c
new file mode 100644
index 000000000000..d7a723b446c3
--- /dev/null
+++ b/arch/riscv/kernel/efi.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ * Adapted from arch/arm64/kernel/efi.c
+ */
+
+#include <linux/efi.h>
+#include <linux/init.h>
+
+#include <asm/efi.h>
+#include <asm/pgtable.h>
+#include <asm/pgtable-bits.h>
+
+/*
+ * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
+ * executable, everything else can be mapped with the XN bits
+ * set. Also take the new (optional) RO/XP bits into account.
+ */
+static __init pgprot_t efimem_to_pgprot_map(efi_memory_desc_t *md)
+{
+ u64 attr = md->attribute;
+ u32 type = md->type;
+
+ if (type == EFI_MEMORY_MAPPED_IO)
+ return PAGE_KERNEL;
+
+ if (WARN_ONCE(!PAGE_ALIGNED(md->phys_addr),
+ "UEFI Runtime regions are not aligned to page size -- buggy firmware?"))
+ /*
+ * If the region is not aligned to the page size of the OS, we
+ * can not use strict permissions, since that would also affect
+ * the mapping attributes of the adjacent regions.
+ */
+ return PAGE_EXEC;
+
+ /* R-- */
+ if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) ==
+ (EFI_MEMORY_XP | EFI_MEMORY_RO))
+ return PAGE_KERNEL_READ;
+
+ /* R-X */
+ if (attr & EFI_MEMORY_RO)
+ return PAGE_KERNEL_READ_EXEC;
+
+ /* RW- */
+ if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) ==
+ EFI_MEMORY_XP) ||
+ type != EFI_RUNTIME_SERVICES_CODE)
+ return PAGE_KERNEL;
+
+ /* RWX */
+ return PAGE_KERNEL_EXEC;
+}
+
+int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
+{
+ pgprot_t prot = __pgprot(pgprot_val(efimem_to_pgprot_map(md)) &
+ ~(_PAGE_GLOBAL));
+ int i;
+
+ /* RISC-V maps one page at a time */
+ for (i = 0; i < md->num_pages; i++)
+ create_pgd_mapping(mm->pgd, md->virt_addr + i * PAGE_SIZE,
+ md->phys_addr + i * PAGE_SIZE,
+ PAGE_SIZE, prot);
+ return 0;
+}
+
+static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)
+{
+ efi_memory_desc_t *md = data;
+ pte_t pte = READ_ONCE(*ptep);
+ unsigned long val;
+
+ if (md->attribute & EFI_MEMORY_RO) {
+ val = pte_val(pte) & ~_PAGE_WRITE;
+ val = pte_val(pte) | _PAGE_READ;
+ pte = __pte(val);
+ }
+ if (md->attribute & EFI_MEMORY_XP) {
+ val = pte_val(pte) & ~_PAGE_EXEC;
+ pte = __pte(val);
+ }
+ set_pte(ptep, pte);
+
+ return 0;
+}
+
+int __init efi_set_mapping_permissions(struct mm_struct *mm,
+ efi_memory_desc_t *md)
+{
+ BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE &&
+ md->type != EFI_RUNTIME_SERVICES_DATA);
+
+ /*
+ * Calling apply_to_page_range() is only safe on regions that are
+ * guaranteed to be mapped down to pages. Since we are only called
+ * for regions that have been mapped using efi_create_mapping() above
+ * (and this is checked by the generic Memory Attributes table parsing
+ * routines), there is no need to check that again here.
+ */
+ return apply_to_page_range(mm, md->virt_addr,
+ md->num_pages << EFI_PAGE_SHIFT,
+ set_permissions, md);
+}
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index c71788e6aff4..7f2a0d6dca7d 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -17,6 +17,7 @@
#include <linux/sched/task.h>
#include <linux/swiotlb.h>
#include <linux/smp.h>
+#include <linux/efi.h>

#include <asm/clint.h>
#include <asm/cpu_ops.h>
@@ -26,11 +27,12 @@
#include <asm/tlbflush.h>
#include <asm/thread_info.h>
#include <asm/kasan.h>
+#include <asm/efi.h>

#include "head.h"

-#ifdef CONFIG_DUMMY_CONSOLE
-struct screen_info screen_info = {
+#if defined(CONFIG_DUMMY_CONSOLE) || defined(CONFIG_EFI)
+struct screen_info screen_info __section(.data) = {
.orig_video_lines = 30,
.orig_video_cols = 80,
.orig_video_mode = 0,
@@ -75,6 +77,7 @@ void __init setup_arch(char **cmdline_p)
early_ioremap_setup();
parse_early_param();

+ efi_init();
setup_bootmem();
paging_init();
#if IS_ENABLED(CONFIG_BUILTIN_DTB)
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index cba03fec08c1..d2121bcf58c6 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -359,7 +359,7 @@ static void __init create_pmd_mapping(pmd_t *pmdp,
#define fixmap_pgd_next fixmap_pte
#endif

-static void __init create_pgd_mapping(pgd_t *pgdp,
+void __init create_pgd_mapping(pgd_t *pgdp,
uintptr_t va, phys_addr_t pa,
phys_addr_t sz, pgprot_t prot)
{
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 61fd1e8b26fb..4d628081bb2f 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -35,6 +35,8 @@ fake_map-$(CONFIG_X86) += x86_fake_mem.o
arm-obj-$(CONFIG_EFI) := efi-init.o arm-runtime.o
obj-$(CONFIG_ARM) += $(arm-obj-y)
obj-$(CONFIG_ARM64) += $(arm-obj-y)
+riscv-obj-$(CONFIG_EFI) := efi-init.o riscv-runtime.o
+obj-$(CONFIG_RISCV) += $(riscv-obj-y)
obj-$(CONFIG_EFI_CAPSULE_LOADER) += capsule-loader.o
obj-$(CONFIG_EFI_EARLYCON) += earlycon.o
obj-$(CONFIG_UEFI_CPER_ARM) += cper-arm.o
diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
index a5a405d8ab44..5c26725d8fd0 100644
--- a/drivers/firmware/efi/libstub/efi-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -17,7 +17,10 @@

/*
* This is the base address at which to start allocating virtual memory ranges
- * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
+ * for UEFI Runtime Services.
+ *
+ * For ARM/ARM64:
+ * This is in the low TTBR0 range so that we can use
* any allocation we choose, and eliminate the risk of a conflict after kexec.
* The value chosen is the largest non-zero power of 2 suitable for this purpose
* both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
@@ -25,6 +28,12 @@
* Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
* map everything below 1 GB. (512 MB is a reasonable upper bound for the
* entire footprint of the UEFI runtime services memory regions)
+ *
+ * For RISC-V:
+ * There is no specific reason for which, this address (512MB) can't be used
+ * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
+ * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
+ * as well to minimize the code churn.
*/
#define EFI_RT_VIRTUAL_BASE SZ_512M
#define EFI_RT_VIRTUAL_SIZE SZ_512M
diff --git a/drivers/firmware/efi/riscv-runtime.c b/drivers/firmware/efi/riscv-runtime.c
new file mode 100644
index 000000000000..d28e715d2bcc
--- /dev/null
+++ b/drivers/firmware/efi/riscv-runtime.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Extensible Firmware Interface
+ *
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Based on Extensible Firmware Interface Specification version 2.4
+ * Adapted from drivers/firmware/efi/arm-runtime.c
+ *
+ */
+
+#include <linux/dmi.h>
+#include <linux/efi.h>
+#include <linux/io.h>
+#include <linux/memblock.h>
+#include <linux/mm_types.h>
+#include <linux/preempt.h>
+#include <linux/rbtree.h>
+#include <linux/rwsem.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/pgtable.h>
+
+#include <asm/cacheflush.h>
+#include <asm/efi.h>
+#include <asm/mmu.h>
+#include <asm/pgalloc.h>
+
+static bool __init efi_virtmap_init(void)
+{
+ efi_memory_desc_t *md;
+
+ efi_mm.pgd = pgd_alloc(&efi_mm);
+ mm_init_cpumask(&efi_mm);
+ init_new_context(NULL, &efi_mm);
+
+ for_each_efi_memory_desc(md) {
+ phys_addr_t phys = md->phys_addr;
+ int ret;
+
+ if (!(md->attribute & EFI_MEMORY_RUNTIME))
+ continue;
+ if (md->virt_addr == 0)
+ return false;
+
+ ret = efi_create_mapping(&efi_mm, md);
+ if (ret) {
+ pr_warn(" EFI remap %pa: failed to create mapping (%d)\n",
+ &phys, ret);
+ return false;
+ }
+ }
+
+ if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
+ return false;
+
+ return true;
+}
+
+/*
+ * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
+ * non-early mapping of the UEFI system table and virtual mappings for all
+ * EFI_MEMORY_RUNTIME regions.
+ */
+static int __init riscv_enable_runtime_services(void)
+{
+ u64 mapsize;
+
+ if (!efi_enabled(EFI_BOOT)) {
+ pr_info("EFI services will not be available.\n");
+ return 0;
+ }
+
+ efi_memmap_unmap();
+
+ mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
+
+ if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
+ pr_err("Failed to remap EFI memory map\n");
+ return 0;
+ }
+
+ if (efi_soft_reserve_enabled()) {
+ efi_memory_desc_t *md;
+
+ for_each_efi_memory_desc(md) {
+ int md_size = md->num_pages << EFI_PAGE_SHIFT;
+ struct resource *res;
+
+ if (!(md->attribute & EFI_MEMORY_SP))
+ continue;
+
+ res = kzalloc(sizeof(*res), GFP_KERNEL);
+ if (WARN_ON(!res))
+ break;
+
+ res->start = md->phys_addr;
+ res->end = md->phys_addr + md_size - 1;
+ res->name = "Soft Reserved";
+ res->flags = IORESOURCE_MEM;
+ res->desc = IORES_DESC_SOFT_RESERVED;
+
+ insert_resource(&iomem_resource, res);
+ }
+ }
+
+ if (efi_runtime_disabled()) {
+ pr_info("EFI runtime services will be disabled.\n");
+ return 0;
+ }
+
+ if (efi_enabled(EFI_RUNTIME_SERVICES)) {
+ pr_info("EFI runtime services access via paravirt.\n");
+ return 0;
+ }
+
+ pr_info("Remapping and enabling EFI services.\n");
+
+ if (!efi_virtmap_init()) {
+ pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
+ return -ENOMEM;
+ }
+
+ /* Set up runtime services function pointers */
+ efi_native_runtime_setup();
+ set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+
+ return 0;
+}
+early_initcall(riscv_enable_runtime_services);
+
+void efi_virtmap_load(void)
+{
+ preempt_disable();
+ switch_mm(current->active_mm, &efi_mm, NULL);
+}
+
+void efi_virtmap_unload(void)
+{
+ switch_mm(&efi_mm, current->active_mm, NULL);
+ preempt_enable();
+}
--
2.24.0