This enables the UEFI Runtime Services needed to manipulate the
non-volatile variable store when running under a BE kernel.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/arm64/include/asm/efi.h | 2 +
arch/arm64/kernel/efi-be-call.S | 55 ++++++++++++++++++++
arch/arm64/kernel/efi-be-runtime.c | 104 +++++++++++++++++++++++++++++++++++++
arch/arm64/kernel/efi.c | 15 ++++++
4 files changed, 176 insertions(+)
create mode 100644 arch/arm64/kernel/efi-be-call.S
create mode 100644 arch/arm64/kernel/efi-be-runtime.c
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index a34fd3b12e2b..44e642b6ab61 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -44,4 +44,6 @@ extern void efi_idmap_init(void);
#define efi_call_early(f, ...) sys_table_arg->boottime->f(__VA_ARGS__)
+extern void efi_be_runtime_setup(void);
+
#endif /* _ASM_EFI_H */
diff --git a/arch/arm64/kernel/efi-be-call.S b/arch/arm64/kernel/efi-be-call.S
new file mode 100644
index 000000000000..24c92a4c352b
--- /dev/null
+++ b/arch/arm64/kernel/efi-be-call.S
@@ -0,0 +1,55 @@
+
+#include <linux/linkage.h>
+
+ .text
+ .align 3
+ENTRY(efi_be_phys_call)
+ /*
+ * Entered at physical address with 1:1 mapping enabled.
+ */
+ stp x29, x30, [sp, #-96]!
+ mov x29, sp
+ str x27, [sp, #16]
+
+ ldr x8, =efi_be_phys_call // virt address of this function
+ adr x9, efi_be_phys_call // phys address of this function
+ sub x9, x8, x9 // calculate virt to phys offset in x9
+
+ /* preserve all inputs */
+ stp x0, x1, [sp, #32]
+ stp x2, x3, [sp, #48]
+ stp x4, x5, [sp, #64]
+ stp x6, x7, [sp, #80]
+
+ /* get phys address of stack */
+ sub sp, sp, x9
+
+ /* switch to LE, disable MMU and D-cache but leave I-cache enabled */
+ mrs x27, sctlr_el1
+ bic x8, x27, #1 << 2 // clear SCTLR.C
+ msr sctlr_el1, x8
+
+ bl flush_cache_all
+
+ /* restore inputs but rotated by 1 register */
+ ldp x7, x0, [sp, #32]
+ ldp x1, x2, [sp, #48]
+ ldp x3, x4, [sp, #64]
+ ldp x5, x6, [sp, #80]
+
+ bic x8, x27, #1 << 2 // clear SCTLR.C
+ bic x8, x8, #1 << 0 // clear SCTLR.M
+ bic x8, x8, #1 << 25 // clear SCTLR.EE
+ msr sctlr_el1, x8
+ isb
+
+ blr x7
+
+ /* switch back to BE and reenable MMU and D-cache */
+ msr sctlr_el1, x27
+
+ mov sp, x29
+ ldr x27, [sp, #16]
+ ldp x29, x30, [sp], #96
+ ret
+ENDPROC(efi_be_phys_call)
diff --git a/arch/arm64/kernel/efi-be-runtime.c b/arch/arm64/kernel/efi-be-runtime.c
new file mode 100644
index 000000000000..62e6c441b77b
--- /dev/null
+++ b/arch/arm64/kernel/efi-be-runtime.c
@@ -0,0 +1,104 @@
+
+#include <linux/efi.h>
+#include <linux/spinlock.h>
+#include <asm/efi.h>
+#include <asm/neon.h>
+#include <asm/tlbflush.h>
+
+static efi_runtime_services_t *runtime;
+static efi_status_t (*efi_be_call)(phys_addr_t func, ...);
+
+static DEFINE_SPINLOCK(efi_be_rt_lock);
+
+static unsigned long efi_be_call_pre(void)
+{
+ unsigned long flags;
+
+ kernel_neon_begin();
+ spin_lock_irqsave(&efi_be_rt_lock, flags);
+ cpu_switch_mm(idmap_pg_dir, &init_mm);
+ flush_tlb_all();
+ return flags;
+}
+
+static void efi_be_call_post(unsigned long flags)
+{
+ cpu_switch_mm(current, current->active_mm);
+ flush_tlb_all();
+ spin_unlock_irqrestore(&efi_be_rt_lock, flags);
+ kernel_neon_end();
+}
+
+static efi_status_t efi_be_get_variable(efi_char16_t *name,
+ efi_guid_t *vendor,
+ u32 *attr,
+ unsigned long *data_size,
+ void *data)
+{
+ unsigned long flags;
+ efi_status_t status;
+
+ *data_size = cpu_to_le64(*data_size);
+ flags = efi_be_call_pre();
+ status = efi_be_call(le64_to_cpu(runtime->get_variable),
+ virt_to_phys(name), virt_to_phys(vendor),
+ virt_to_phys(attr), virt_to_phys(data_size),
+ virt_to_phys(data));
+ efi_be_call_post(flags);
+ *attr = le32_to_cpu(*attr);
+ *data_size = le64_to_cpu(*data_size);
+ return status;
+}
+
+static efi_status_t efi_be_get_next_variable(unsigned long *name_size,
+ efi_char16_t *name,
+ efi_guid_t *vendor)
+{
+ unsigned long flags;
+ efi_status_t status;
+
+ *name_size = cpu_to_le64(*name_size);
+ flags = efi_be_call_pre();
+ status = efi_be_call(le64_to_cpu(runtime->get_next_variable),
+ virt_to_phys(name_size), virt_to_phys(name),
+ virt_to_phys(vendor));
+ efi_be_call_post(flags);
+ *name_size = le64_to_cpu(*name_size);
+ return status;
+}
+
+static efi_status_t efi_be_set_variable(efi_char16_t *name,
+ efi_guid_t *vendor,
+ u32 attr,
+ unsigned long data_size,
+ void *data)
+{
+ unsigned long flags;
+ efi_status_t status;
+
+ flags = efi_be_call_pre();
+ status = efi_be_call(le64_to_cpu(runtime->set_variable),
+ virt_to_phys(name), virt_to_phys(vendor),
+ cpu_to_le32(attr), cpu_to_le64(data_size),
+ virt_to_phys(data));
+ efi_be_call_post(flags);
+ return status;
+}
+
+void efi_be_runtime_setup(void)
+{
+ extern u8 efi_be_phys_call[];
+
+ runtime = ioremap_cache(le64_to_cpu(efi.systab->runtime),
+ sizeof(efi_runtime_services_t));
+ if (!runtime) {
+ pr_err("Failed to set up BE wrappers for UEFI Runtime Services!\n");
+ return;
+ }
+
+ efi_be_call = (void *)virt_to_phys(efi_be_phys_call);
+
+ efi.get_variable = efi_be_get_variable;
+ efi.get_next_variable = efi_be_get_next_variable;
+ efi.set_variable = efi_be_set_variable;
+}
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 96df58824189..21e98810c5dd 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -406,6 +406,21 @@ static int __init arm64_enter_virtual_mode(void)
efi.memmap = &memmap;
+ if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) {
+ efi.systab = ioremap_cache(efi_system_table,
+ sizeof(efi_system_table_t));
+ if (!efi.systab) {
+ pr_err("Failed to remap EFI system table!\n");
+ return -1;
+ }
+ free_boot_services();
+ efi_be_runtime_setup();
+
+ set_bit(EFI_SYSTEM_TABLES, &efi.flags);
+ set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+ return 0;
+ }
+
/* Map the runtime regions */
virtmap = kmalloc(mapsize, GFP_KERNEL);
if (!virtmap) {
--
1.8.3.2
--
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