[tip:efi/core] efi/arm-stub: Round up FDT allocation to mapping size

tip-bot for Ard Biesheuvel
2017-04-05T10:40:43Z

Commit-ID: 24d7c494ce46d5bb6c8fd03e88a48ae249ec1492
Gitweb: http://git.kernel.org/tip/24d7c494ce46d5bb6c8fd03e88a48ae249ec1492
Author: Ard Biesheuvel <ard.biesheuvel@linaro.org>
AuthorDate: Tue, 4 Apr 2017 17:02:39 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 5 Apr 2017 12:27:24 +0200

efi/arm-stub: Round up FDT allocation to mapping size

The FDT is mapped via a fixmap entry that is at least 2 MB in size and
2 MB aligned on 4 KB page size kernels.

On UEFI systems, the FDT allocation may share this 2 MB mapping with a
reserved region (or another memory region that we should never map),
unless we account for this in the size of the allocation (the alignment
is already 2 MB)

So instead of taking guesses at the needed space, simply allocate 2 MB
immediately. The allocation will be recorded as EFI_LOADER_DATA, and the
kernel only memblock_reserve()'s the actual size of the FDT, so the
unused space will be released back to the kernel.

Reviewed-By: Jeffrey Hugo <jhugo@codeaurora.org>
Tested-by: Richard Ruigrok <rruigrok@codeaurora.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170404160245.27812-6-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/arm64/include/asm/efi.h | 1 +
drivers/firmware/efi/libstub/fdt.c | 57 ++++++++++++++++----------------------
2 files changed, 25 insertions(+), 33 deletions(-)

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 083a52d3..8f3043a 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -1,6 +1,7 @@
#ifndef _ASM_EFI_H
#define _ASM_EFI_H

+#include <asm/boot.h>
#include <asm/cpufeature.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 260c4b4..41f457b 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -206,6 +206,10 @@ static efi_status_t exit_boot_func(efi_system_table_t *sys_table_arg,
return update_fdt_memmap(p->new_fdt_addr, map);
}

+#ifndef MAX_FDT_SIZE
+#define MAX_FDT_SIZE SZ_2M
+#endif
+
/*
* Allocate memory for a new FDT, then add EFI, commandline, and
* initrd related fields to the FDT. This routine increases the
@@ -233,7 +237,6 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
u32 desc_ver;
unsigned long mmap_key;
efi_memory_desc_t *memory_map, *runtime_map;
- unsigned long new_fdt_size;
efi_status_t status;
int runtime_entry_count = 0;
struct efi_boot_memmap map;
@@ -262,41 +265,29 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
"Exiting boot services and installing virtual address map...\n");

map.map = &memory_map;
+ status = efi_high_alloc(sys_table, MAX_FDT_SIZE, EFI_FDT_ALIGN,
+ new_fdt_addr, max_addr);
+ if (status != EFI_SUCCESS) {
+ pr_efi_err(sys_table,
+ "Unable to allocate memory for new device tree.\n");
+ goto fail;
+ }
+
/*
- * Estimate size of new FDT, and allocate memory for it. We
- * will allocate a bigger buffer if this ends up being too
- * small, so a rough guess is OK here.
+ * Now that we have done our final memory allocation (and free)
+ * we can get the memory map key needed for exit_boot_services().
*/
- new_fdt_size = fdt_size + EFI_PAGE_SIZE;
- while (1) {
- status = efi_high_alloc(sys_table, new_fdt_size, EFI_FDT_ALIGN,
- new_fdt_addr, max_addr);
- if (status != EFI_SUCCESS) {
- pr_efi_err(sys_table, "Unable to allocate memory for new device tree.\n");
- goto fail;
- }
-
- status = update_fdt(sys_table,
- (void *)fdt_addr, fdt_size,
- (void *)*new_fdt_addr, new_fdt_size,
- cmdline_ptr, initrd_addr, initrd_size);
+ status = efi_get_memory_map(sys_table, &map);
+ if (status != EFI_SUCCESS)
+ goto fail_free_new_fdt;

- /* Succeeding the first time is the expected case. */
- if (status == EFI_SUCCESS)
- break;
+ status = update_fdt(sys_table, (void *)fdt_addr, fdt_size,
+ (void *)*new_fdt_addr, MAX_FDT_SIZE, cmdline_ptr,
+ initrd_addr, initrd_size);

- if (status == EFI_BUFFER_TOO_SMALL) {
- /*
- * We need to allocate more space for the new
- * device tree, so free existing buffer that is
- * too small.
- */
- efi_free(sys_table, new_fdt_size, *new_fdt_addr);
- new_fdt_size += EFI_PAGE_SIZE;
- } else {
- pr_efi_err(sys_table, "Unable to construct new device tree.\n");
- goto fail_free_new_fdt;
- }
+ if (status != EFI_SUCCESS) {
+ pr_efi_err(sys_table, "Unable to construct new device tree.\n");
+ goto fail_free_new_fdt;
}

priv.runtime_map = runtime_map;
@@ -340,7 +331,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
pr_efi_err(sys_table, "Exit boot services failed.\n");

fail_free_new_fdt:
- efi_free(sys_table, new_fdt_size, *new_fdt_addr);
+ efi_free(sys_table, MAX_FDT_SIZE, *new_fdt_addr);

fail:
sys_table->boottime->free_pool(runtime_map);