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Subject[PATCH] RISC-V: Relocate the kernel relative to a DRAM base.
Date
Try to get the base of the DRAM from a DTB to use it as a lowest address
in physical memory to relocate the kernel. If it is not possible to
obtain the base from a /memory node of the DTB let's make an assumption
that the DRAM base at the beginning of the memory.

Signed-off-by: Nikita Ermakov <arei@altlinux.org>
---
drivers/firmware/efi/libstub/riscv-stub.c | 39 ++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
index 380e4e251399..1b5944276e1a 100644
--- a/drivers/firmware/efi/libstub/riscv-stub.c
+++ b/drivers/firmware/efi/libstub/riscv-stub.c
@@ -46,6 +46,39 @@ static u32 get_boot_hartid_from_fdt(void)
return fdt32_to_cpu(*prop);
}

+static unsigned long get_dram_base_from_fdt(void)
+{
+ const void *fdt;
+ int node, len;
+ const fdt32_t *addr_cells;
+ const void *prop;
+
+ fdt = get_efi_config_table(DEVICE_TREE_GUID);
+ if (!fdt)
+ return ULONG_MAX;
+
+ node = fdt_path_offset(fdt, "/");
+ if (node < 0)
+ return ULONG_MAX;
+
+ addr_cells = fdt_getprop((void *)fdt, node, "#address-cells", &len);
+ if (!addr_cells)
+ return ULONG_MAX;
+
+ node = fdt_path_offset(fdt, "/memory");
+ if (node < 0)
+ return ULONG_MAX;
+
+ prop = fdt_getprop((void *)fdt, node, "reg", &len);
+ if (!prop)
+ return ULONG_MAX;
+
+ if (fdt32_to_cpu(*addr_cells) > 1)
+ return fdt64_to_cpu(*((fdt64_t *)prop));
+ else
+ return fdt32_to_cpu(*((fdt32_t *)prop));
+}
+
efi_status_t check_platform_features(void)
{
hartid = get_boot_hartid_from_fdt();
@@ -97,7 +130,11 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
* lowest possible memory region as long as the address and size meets
* the alignment constraints.
*/
- preferred_addr = MIN_KIMG_ALIGN;
+ preferred_addr = get_dram_base_from_fdt();
+ if (preferred_addr == ULONG_MAX)
+ preferred_addr = MIN_KIMG_ALIGN;
+ else
+ preferred_addr += MIN_KIMG_ALIGN;
status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
preferred_addr, MIN_KIMG_ALIGN, 0x0);

--
2.29.3
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