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efi_loader: Add U-Boot memory to the EFI memory map

Message ID 20241129163511.767015-1-ilias.apalodimas@linaro.org
State Superseded
Headers show
Series efi_loader: Add U-Boot memory to the EFI memory map | expand

Commit Message

Ilias Apalodimas Nov. 29, 2024, 4:35 p.m. UTC 
This code was removed when the EFI subsystem started using LMB calls for
the reservations. In hindsight it unearthed two problems.

The e820 code is adding u-boot memory as EfiReservedMemory while it
should look at what LMB added and decide instead of blindly overwriting
it. Thew reason this worked is that we marked that code properly late,
when the EFI came up. But now with the LMB changes, the EFI map gets
added first and the e820 code overwrites it.

The second problem is that we never mark SetVirtualAddressMap as runtime
code, which we should according to the spec. Until we fix this this hack
can't go away, at least for architectures that *need* to call SVAM.
More specifically x86 which currently requires SVAM, sets the NX bit for
pages not marked as *_CODE. So unless we do that late, it will crash
trying to execute from non-executable memory.

Notably arm64 disables it explicitly if the VA space is > 48bits, so
doesn't suffer from any of these problems.

This doesn't really deserve a fixes tag, since it brings back a hack to
rememdy a sitation that was wrong long before that commit, but in case
anyone hits the same bug ...

Fixes: commit a68c9ac5d8af ("efi_memory: do not add U-Boot memory to the memory map"
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
---
 lib/efi_loader/efi_memory.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
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Patch

diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index e493934c7131..edd7da7d8c6e 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -814,7 +814,16 @@  static void add_u_boot_and_runtime(void)
 {
 	unsigned long runtime_start, runtime_end, runtime_pages;
 	unsigned long runtime_mask = EFI_PAGE_MASK;
-
+	unsigned long uboot_start, uboot_pages;
+	unsigned long uboot_stack_size = CONFIG_STACK_SIZE;
+
+	/* Add U-Boot */
+	uboot_start = ((uintptr_t)map_sysmem(gd->start_addr_sp, 0) -
+		       uboot_stack_size) & ~EFI_PAGE_MASK;
+	uboot_pages = ((uintptr_t)map_sysmem(gd->ram_top - 1, 0) -
+		       uboot_start + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
+	efi_add_memory_map_pg(uboot_start, uboot_pages, EFI_BOOT_SERVICES_CODE,
+			      false);
 #if defined(__aarch64__)
 	/*
 	 * Runtime Services must be 64KiB aligned according to the