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author | Bin Meng <bmeng.cn@gmail.com> | 2020-03-17 17:59:40 +0300 |
---|---|---|
committer | Anup Patel <anup@brainfault.org> | 2020-03-18 06:49:44 +0300 |
commit | fcb1dedb2d4d2f2d77a165b1078244caf13363be (patch) | |
tree | dc52d9af343ed4560c95b34ed6ac9114b1f6a758 | |
parent | dce88467af77ed60e7b31ab3a9423fe640b8553c (diff) | |
download | opensbi-fcb1dedb2d4d2f2d77a165b1078244caf13363be.tar.xz |
lib: utils: Add a fdt_reserved_memory_fixup() helper
Add a helper routine to insert a child node of the reserved memory
node in the device tree that describes the protected memory region
done by OpenSBI via PMP.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
-rw-r--r-- | include/sbi_utils/fdt/fdt_helper.h | 25 | ||||
-rw-r--r-- | lib/utils/fdt/fdt_helper.c | 142 | ||||
-rw-r--r-- | lib/utils/fdt/objects.mk | 7 |
3 files changed, 174 insertions, 0 deletions
diff --git a/include/sbi_utils/fdt/fdt_helper.h b/include/sbi_utils/fdt/fdt_helper.h new file mode 100644 index 0000000..a6c3073 --- /dev/null +++ b/include/sbi_utils/fdt/fdt_helper.h @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: BSD-2-Clause +/* + * fdt_helper.h - Flat Device Tree manipulation helper routines + * Implement helper routines on top of libfdt for OpenSBI usage + * + * Copyright (C) 2020 Bin Meng <bmeng.cn@gmail.com> + */ + +#ifndef __FDT_HELPER_H__ +#define __FDT_HELPER_H__ + +/** + * Fix up the reserved memory node in the device tree + * + * This routine inserts a child node of the reserved memory node in the device + * tree that describes the protected memory region done by OpenSBI via PMP. + * + * It is recommended that platform codes call this helper in their final_init() + * + * @param fdt: device tree blob + * @return zero on success and -ve on failure + */ +int fdt_reserved_memory_fixup(void *fdt); + +#endif /* __FDT_HELPER_H__ */ diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c new file mode 100644 index 0000000..d95a056 --- /dev/null +++ b/lib/utils/fdt/fdt_helper.c @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: BSD-2-Clause +/* + * fdt_helper.c - Flat Device Tree manipulation helper routines + * Implement helper routines on top of libfdt for OpenSBI usage + * + * Copyright (C) 2020 Bin Meng <bmeng.cn@gmail.com> + */ + +#include <libfdt.h> +#include <sbi/riscv_asm.h> +#include <sbi/sbi_console.h> +#include <sbi/sbi_platform.h> +#include <sbi/sbi_scratch.h> + +/** + * We use PMP to protect OpenSBI firmware to safe-guard it from buggy S-mode + * software, see pmp_init() in lib/sbi/sbi_hart.c. The protected memory region + * information needs to be conveyed to S-mode software (e.g.: operating system) + * via some well-known method. + * + * With device tree, this can be done by inserting a child node of the reserved + * memory node which is used to specify one or more regions of reserved memory. + * + * For the reserved memory node bindings, see Linux kernel documentation at + * Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt + * + * Some additional memory spaces may be protected by platform codes via PMP as + * well, and corresponding child nodes will be inserted. + */ +int fdt_reserved_memory_fixup(void *fdt) +{ + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr(); + const struct sbi_platform *plat = sbi_platform_ptr(scratch); + unsigned long prot, addr, size; + int na = fdt_address_cells(fdt, 0); + int ns = fdt_size_cells(fdt, 0); + fdt32_t addr_high, addr_low; + fdt32_t size_high, size_low; + fdt32_t reg[4]; + fdt32_t *val; + char name[32]; + int parent, subnode; + int i, j; + int err; + + if (!sbi_platform_has_pmp(plat)) + return 0; + + /* expand the device tree to accommodate new node */ + err = fdt_open_into(fdt, fdt, fdt_totalsize(fdt) + 256); + if (err < 0) + return err; + + /* try to locate the reserved memory node */ + parent = fdt_path_offset(fdt, "/reserved-memory"); + if (parent < 0) { + /* if such node does not exist, create one */ + parent = fdt_add_subnode(fdt, 0, "reserved-memory"); + if (parent < 0) + return parent; + + /* + * reserved-memory node has 3 required properties: + * - #address-cells: the same value as the root node + * - #size-cells: the same value as the root node + * - ranges: should be empty + */ + + err = fdt_setprop_empty(fdt, parent, "ranges"); + if (err < 0) + return err; + + err = fdt_setprop_u32(fdt, parent, "#size-cells", ns); + if (err < 0) + return err; + + err = fdt_setprop_u32(fdt, parent, "#address-cells", na); + if (err < 0) + return err; + } + + /* + * We assume the given device tree does not contain any memory region + * child node protected by PMP. Normally PMP programming happens at + * M-mode firmware. The memory space used by OpenSBI is protected. + * Some additional memory spaces may be protected by platform codes. + * + * With above assumption, we create child nodes directly. + */ + + for (i = 0, j = 0; i < PMP_COUNT; i++) { + pmp_get(i, &prot, &addr, &size); + if (!(prot & PMP_A)) + continue; + if (!(prot & (PMP_R | PMP_W | PMP_X))) { + addr_high = (u64)addr >> 32; + addr_low = addr; + size_high = (u64)size >> 32; + size_low = size; + + if (na > 1 && addr_high) + sbi_snprintf(name, sizeof(name), + "mmode_pmp%d@%x,%x", j, + addr_high, addr_low); + else + sbi_snprintf(name, sizeof(name), + "mmode_pmp%d@%x", j, + addr_low); + + subnode = fdt_add_subnode(fdt, parent, name); + if (subnode < 0) + return subnode; + + /* + * Tell operating system not to create a virtual + * mapping of the region as part of its standard + * mapping of system memory. + */ + err = fdt_setprop_empty(fdt, subnode, "no-map"); + if (err < 0) + return err; + + /* encode the <reg> property value */ + val = reg; + if (na > 1) + *val++ = cpu_to_fdt32(addr_high); + *val++ = cpu_to_fdt32(addr_low); + if (ns > 1) + *val++ = cpu_to_fdt32(size_high); + *val++ = cpu_to_fdt32(size_low); + + err = fdt_setprop(fdt, subnode, "reg", reg, + (na + ns) * sizeof(fdt32_t)); + if (err < 0) + return err; + + j++; + } + } + + return 0; +} diff --git a/lib/utils/fdt/objects.mk b/lib/utils/fdt/objects.mk new file mode 100644 index 0000000..062e6bd --- /dev/null +++ b/lib/utils/fdt/objects.mk @@ -0,0 +1,7 @@ +# +# SPDX-License-Identifier: BSD-2-Clause +# +# Copyright (C) 2020 Bin Meng <bmeng.cn@gmail.com> +# + +libsbiutils-objs-y += fdt/fdt_helper.o |