summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/mm/nohash/kaslr_booke.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/powerpc/mm/nohash/kaslr_booke.c')
-rw-r--r--arch/powerpc/mm/nohash/kaslr_booke.c396
1 files changed, 396 insertions, 0 deletions
diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
new file mode 100644
index 000000000..0d04f9d5d
--- /dev/null
+++ b/arch/powerpc/mm/nohash/kaslr_booke.c
@@ -0,0 +1,396 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright (C) 2019 Jason Yan <yanaijie@huawei.com>
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/stddef.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/memblock.h>
+#include <linux/libfdt.h>
+#include <linux/crash_core.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <asm/cacheflush.h>
+#include <asm/kdump.h>
+#include <mm/mmu_decl.h>
+#include <generated/utsrelease.h>
+
+struct regions {
+ unsigned long pa_start;
+ unsigned long pa_end;
+ unsigned long kernel_size;
+ unsigned long dtb_start;
+ unsigned long dtb_end;
+ unsigned long initrd_start;
+ unsigned long initrd_end;
+ unsigned long crash_start;
+ unsigned long crash_end;
+ int reserved_mem;
+ int reserved_mem_addr_cells;
+ int reserved_mem_size_cells;
+};
+
+struct regions __initdata regions;
+
+static __init void kaslr_get_cmdline(void *fdt)
+{
+ early_init_dt_scan_chosen(boot_command_line);
+}
+
+static unsigned long __init rotate_xor(unsigned long hash, const void *area,
+ size_t size)
+{
+ size_t i;
+ const unsigned long *ptr = area;
+
+ for (i = 0; i < size / sizeof(hash); i++) {
+ /* Rotate by odd number of bits and XOR. */
+ hash = (hash << ((sizeof(hash) * 8) - 7)) | (hash >> 7);
+ hash ^= ptr[i];
+ }
+
+ return hash;
+}
+
+/* Attempt to create a simple starting entropy. This can make it defferent for
+ * every build but it is still not enough. Stronger entropy should
+ * be added to make it change for every boot.
+ */
+static unsigned long __init get_boot_seed(void *fdt)
+{
+ unsigned long hash = 0;
+
+ /* build-specific string for starting entropy. */
+ hash = rotate_xor(hash, linux_banner, strlen(linux_banner));
+ hash = rotate_xor(hash, fdt, fdt_totalsize(fdt));
+
+ return hash;
+}
+
+static __init u64 get_kaslr_seed(void *fdt)
+{
+ int node, len;
+ fdt64_t *prop;
+ u64 ret;
+
+ node = fdt_path_offset(fdt, "/chosen");
+ if (node < 0)
+ return 0;
+
+ prop = fdt_getprop_w(fdt, node, "kaslr-seed", &len);
+ if (!prop || len != sizeof(u64))
+ return 0;
+
+ ret = fdt64_to_cpu(*prop);
+ *prop = 0;
+ return ret;
+}
+
+static __init bool regions_overlap(u32 s1, u32 e1, u32 s2, u32 e2)
+{
+ return e1 >= s2 && e2 >= s1;
+}
+
+static __init bool overlaps_reserved_region(const void *fdt, u32 start,
+ u32 end)
+{
+ int subnode, len, i;
+ u64 base, size;
+
+ /* check for overlap with /memreserve/ entries */
+ for (i = 0; i < fdt_num_mem_rsv(fdt); i++) {
+ if (fdt_get_mem_rsv(fdt, i, &base, &size) < 0)
+ continue;
+ if (regions_overlap(start, end, base, base + size))
+ return true;
+ }
+
+ if (regions.reserved_mem < 0)
+ return false;
+
+ /* check for overlap with static reservations in /reserved-memory */
+ for (subnode = fdt_first_subnode(fdt, regions.reserved_mem);
+ subnode >= 0;
+ subnode = fdt_next_subnode(fdt, subnode)) {
+ const fdt32_t *reg;
+ u64 rsv_end;
+
+ len = 0;
+ reg = fdt_getprop(fdt, subnode, "reg", &len);
+ while (len >= (regions.reserved_mem_addr_cells +
+ regions.reserved_mem_size_cells)) {
+ base = fdt32_to_cpu(reg[0]);
+ if (regions.reserved_mem_addr_cells == 2)
+ base = (base << 32) | fdt32_to_cpu(reg[1]);
+
+ reg += regions.reserved_mem_addr_cells;
+ len -= 4 * regions.reserved_mem_addr_cells;
+
+ size = fdt32_to_cpu(reg[0]);
+ if (regions.reserved_mem_size_cells == 2)
+ size = (size << 32) | fdt32_to_cpu(reg[1]);
+
+ reg += regions.reserved_mem_size_cells;
+ len -= 4 * regions.reserved_mem_size_cells;
+
+ if (base >= regions.pa_end)
+ continue;
+
+ rsv_end = min(base + size, (u64)U32_MAX);
+
+ if (regions_overlap(start, end, base, rsv_end))
+ return true;
+ }
+ }
+ return false;
+}
+
+static __init bool overlaps_region(const void *fdt, u32 start,
+ u32 end)
+{
+ if (regions_overlap(start, end, __pa(_stext), __pa(_end)))
+ return true;
+
+ if (regions_overlap(start, end, regions.dtb_start,
+ regions.dtb_end))
+ return true;
+
+ if (regions_overlap(start, end, regions.initrd_start,
+ regions.initrd_end))
+ return true;
+
+ if (regions_overlap(start, end, regions.crash_start,
+ regions.crash_end))
+ return true;
+
+ return overlaps_reserved_region(fdt, start, end);
+}
+
+static void __init get_crash_kernel(void *fdt, unsigned long size)
+{
+#ifdef CONFIG_CRASH_CORE
+ unsigned long long crash_size, crash_base;
+ int ret;
+
+ ret = parse_crashkernel(boot_command_line, size, &crash_size,
+ &crash_base);
+ if (ret != 0 || crash_size == 0)
+ return;
+ if (crash_base == 0)
+ crash_base = KDUMP_KERNELBASE;
+
+ regions.crash_start = (unsigned long)crash_base;
+ regions.crash_end = (unsigned long)(crash_base + crash_size);
+
+ pr_debug("crash_base=0x%llx crash_size=0x%llx\n", crash_base, crash_size);
+#endif
+}
+
+static void __init get_initrd_range(void *fdt)
+{
+ u64 start, end;
+ int node, len;
+ const __be32 *prop;
+
+ node = fdt_path_offset(fdt, "/chosen");
+ if (node < 0)
+ return;
+
+ prop = fdt_getprop(fdt, node, "linux,initrd-start", &len);
+ if (!prop)
+ return;
+ start = of_read_number(prop, len / 4);
+
+ prop = fdt_getprop(fdt, node, "linux,initrd-end", &len);
+ if (!prop)
+ return;
+ end = of_read_number(prop, len / 4);
+
+ regions.initrd_start = (unsigned long)start;
+ regions.initrd_end = (unsigned long)end;
+
+ pr_debug("initrd_start=0x%llx initrd_end=0x%llx\n", start, end);
+}
+
+static __init unsigned long get_usable_address(const void *fdt,
+ unsigned long start,
+ unsigned long offset)
+{
+ unsigned long pa;
+ unsigned long pa_end;
+
+ for (pa = offset; (long)pa > (long)start; pa -= SZ_16K) {
+ pa_end = pa + regions.kernel_size;
+ if (overlaps_region(fdt, pa, pa_end))
+ continue;
+
+ return pa;
+ }
+ return 0;
+}
+
+static __init void get_cell_sizes(const void *fdt, int node, int *addr_cells,
+ int *size_cells)
+{
+ const int *prop;
+ int len;
+
+ /*
+ * Retrieve the #address-cells and #size-cells properties
+ * from the 'node', or use the default if not provided.
+ */
+ *addr_cells = *size_cells = 1;
+
+ prop = fdt_getprop(fdt, node, "#address-cells", &len);
+ if (len == 4)
+ *addr_cells = fdt32_to_cpu(*prop);
+ prop = fdt_getprop(fdt, node, "#size-cells", &len);
+ if (len == 4)
+ *size_cells = fdt32_to_cpu(*prop);
+}
+
+static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned long index,
+ unsigned long offset)
+{
+ unsigned long koffset = 0;
+ unsigned long start;
+
+ while ((long)index >= 0) {
+ offset = memstart_addr + index * SZ_64M + offset;
+ start = memstart_addr + index * SZ_64M;
+ koffset = get_usable_address(dt_ptr, start, offset);
+ if (koffset)
+ break;
+ index--;
+ }
+
+ if (koffset != 0)
+ koffset -= memstart_addr;
+
+ return koffset;
+}
+
+static inline __init bool kaslr_disabled(void)
+{
+ return strstr(boot_command_line, "nokaslr") != NULL;
+}
+
+static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size,
+ unsigned long kernel_sz)
+{
+ unsigned long offset, random;
+ unsigned long ram, linear_sz;
+ u64 seed;
+ unsigned long index;
+
+ kaslr_get_cmdline(dt_ptr);
+ if (kaslr_disabled())
+ return 0;
+
+ random = get_boot_seed(dt_ptr);
+
+ seed = get_tb() << 32;
+ seed ^= get_tb();
+ random = rotate_xor(random, &seed, sizeof(seed));
+
+ /*
+ * Retrieve (and wipe) the seed from the FDT
+ */
+ seed = get_kaslr_seed(dt_ptr);
+ if (seed)
+ random = rotate_xor(random, &seed, sizeof(seed));
+ else
+ pr_warn("KASLR: No safe seed for randomizing the kernel base.\n");
+
+ ram = min_t(phys_addr_t, __max_low_memory, size);
+ ram = map_mem_in_cams(ram, CONFIG_LOWMEM_CAM_NUM, true, true);
+ linear_sz = min_t(unsigned long, ram, SZ_512M);
+
+ /* If the linear size is smaller than 64M, do not randomize */
+ if (linear_sz < SZ_64M)
+ return 0;
+
+ /* check for a reserved-memory node and record its cell sizes */
+ regions.reserved_mem = fdt_path_offset(dt_ptr, "/reserved-memory");
+ if (regions.reserved_mem >= 0)
+ get_cell_sizes(dt_ptr, regions.reserved_mem,
+ &regions.reserved_mem_addr_cells,
+ &regions.reserved_mem_size_cells);
+
+ regions.pa_start = memstart_addr;
+ regions.pa_end = memstart_addr + linear_sz;
+ regions.dtb_start = __pa(dt_ptr);
+ regions.dtb_end = __pa(dt_ptr) + fdt_totalsize(dt_ptr);
+ regions.kernel_size = kernel_sz;
+
+ get_initrd_range(dt_ptr);
+ get_crash_kernel(dt_ptr, ram);
+
+ /*
+ * Decide which 64M we want to start
+ * Only use the low 8 bits of the random seed
+ */
+ index = random & 0xFF;
+ index %= linear_sz / SZ_64M;
+
+ /* Decide offset inside 64M */
+ offset = random % (SZ_64M - kernel_sz);
+ offset = round_down(offset, SZ_16K);
+
+ return kaslr_legal_offset(dt_ptr, index, offset);
+}
+
+/*
+ * To see if we need to relocate the kernel to a random offset
+ * void *dt_ptr - address of the device tree
+ * phys_addr_t size - size of the first memory block
+ */
+notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
+{
+ unsigned long tlb_virt;
+ phys_addr_t tlb_phys;
+ unsigned long offset;
+ unsigned long kernel_sz;
+
+ kernel_sz = (unsigned long)_end - (unsigned long)_stext;
+
+ offset = kaslr_choose_location(dt_ptr, size, kernel_sz);
+ if (offset == 0)
+ return;
+
+ kernstart_virt_addr += offset;
+ kernstart_addr += offset;
+
+ is_second_reloc = 1;
+
+ if (offset >= SZ_64M) {
+ tlb_virt = round_down(kernstart_virt_addr, SZ_64M);
+ tlb_phys = round_down(kernstart_addr, SZ_64M);
+
+ /* Create kernel map to relocate in */
+ create_kaslr_tlb_entry(1, tlb_virt, tlb_phys);
+ }
+
+ /* Copy the kernel to it's new location and run */
+ memcpy((void *)kernstart_virt_addr, (void *)_stext, kernel_sz);
+ flush_icache_range(kernstart_virt_addr, kernstart_virt_addr + kernel_sz);
+
+ reloc_kernel_entry(dt_ptr, kernstart_virt_addr);
+}
+
+void __init kaslr_late_init(void)
+{
+ /* If randomized, clear the original kernel */
+ if (kernstart_virt_addr != KERNELBASE) {
+ unsigned long kernel_sz;
+
+ kernel_sz = (unsigned long)_end - kernstart_virt_addr;
+ memzero_explicit((void *)KERNELBASE, kernel_sz);
+ }
+}