Merge patch series "riscv: Introduce KASLR"

[platform/kernel/linux-rpi.git] / arch / riscv / mm / init.c

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 943c18d..0798bd8 100644 (file)
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -1014,11 +1014,45 @@ static void __init pt_ops_set_late(void)
 #endif
 }
 
+#ifdef CONFIG_RANDOMIZE_BASE
+extern bool __init __pi_set_nokaslr_from_cmdline(uintptr_t dtb_pa);
+extern u64 __init __pi_get_kaslr_seed(uintptr_t dtb_pa);
+
+static int __init print_nokaslr(char *p)
+{
+       pr_info("Disabled KASLR");
+       return 0;
+}
+early_param("nokaslr", print_nokaslr);
+
+unsigned long kaslr_offset(void)
+{
+       return kernel_map.virt_offset;
+}
+#endif
+
 asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 {
        pmd_t __maybe_unused fix_bmap_spmd, fix_bmap_epmd;
 
-       kernel_map.virt_addr = KERNEL_LINK_ADDR;
+#ifdef CONFIG_RANDOMIZE_BASE
+       if (!__pi_set_nokaslr_from_cmdline(dtb_pa)) {
+               u64 kaslr_seed = __pi_get_kaslr_seed(dtb_pa);
+               u32 kernel_size = (uintptr_t)(&_end) - (uintptr_t)(&_start);
+               u32 nr_pos;
+
+               /*
+                * Compute the number of positions available: we are limited
+                * by the early page table that only has one PUD and we must
+                * be aligned on PMD_SIZE.
+                */
+               nr_pos = (PUD_SIZE - kernel_size) / PMD_SIZE;
+
+               kernel_map.virt_offset = (kaslr_seed % nr_pos) * PMD_SIZE;
+       }
+#endif
+
+       kernel_map.virt_addr = KERNEL_LINK_ADDR + kernel_map.virt_offset;
        kernel_map.page_offset = _AC(CONFIG_PAGE_OFFSET, UL);
 
 #ifdef CONFIG_XIP_KERNEL