RISC-V Fixes for 5.15 (or -rc8)

* A fix to ensure the trap vector's address is aligned.
 * A fix to avoid re-populating the KASAN shadow memory.
 * A fix to allow kasan to build without warnings, which have recently
   become errors.
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Merge tag 'riscv-for-linus-5.15-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V fixes from Palmer Dabbelt:
 "These are pretty late, but they do fix concrete issues.

   - ensure the trap vector's address is aligned.

   - avoid re-populating the KASAN shadow memory.

   - allow kasan to build without warnings, which have recently become
     errors"

* tag 'riscv-for-linus-5.15-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Fix asan-stack clang build
  riscv: Do not re-populate shadow memory with kasan_populate_early_shadow
  riscv: fix misalgned trap vector base address

arch/riscv/Kconfig

@@ -163,6 +163,12 @@ config PAGE_OFFSET
 	default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
 	default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB
 
+config KASAN_SHADOW_OFFSET
+	hex
+	depends on KASAN_GENERIC
+	default 0xdfffffc800000000 if 64BIT
+	default 0xffffffff if 32BIT
+
 config ARCH_FLATMEM_ENABLE
 	def_bool !NUMA
 

arch/riscv/include/asm/kasan.h

@@ -30,8 +30,7 @@
 #define KASAN_SHADOW_SIZE	(UL(1) << ((CONFIG_VA_BITS - 1) - KASAN_SHADOW_SCALE_SHIFT))
 #define KASAN_SHADOW_START	KERN_VIRT_START
 #define KASAN_SHADOW_END	(KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
-#define KASAN_SHADOW_OFFSET	(KASAN_SHADOW_END - (1ULL << \
-					(64 - KASAN_SHADOW_SCALE_SHIFT)))
+#define KASAN_SHADOW_OFFSET	_AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
 
 void kasan_init(void);
 asmlinkage void kasan_early_init(void);

arch/riscv/kernel/head.S

@@ -193,6 +193,7 @@ setup_trap_vector:
 	csrw CSR_SCRATCH, zero
 	ret
 
+.align 2
 .Lsecondary_park:
 	/* We lack SMP support or have too many harts, so park this hart */
 	wfi

arch/riscv/mm/kasan_init.c

@@ -17,6 +17,9 @@ asmlinkage void __init kasan_early_init(void)
 	uintptr_t i;
 	pgd_t *pgd = early_pg_dir + pgd_index(KASAN_SHADOW_START);
 
+	BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
+		KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
+
 	for (i = 0; i < PTRS_PER_PTE; ++i)
 		set_pte(kasan_early_shadow_pte + i,
 			mk_pte(virt_to_page(kasan_early_shadow_page),
@@ -172,21 +175,10 @@ void __init kasan_init(void)
 	phys_addr_t p_start, p_end;
 	u64 i;
 
-	/*
-	 * Populate all kernel virtual address space with kasan_early_shadow_page
-	 * except for the linear mapping and the modules/kernel/BPF mapping.
-	 */
-	kasan_populate_early_shadow((void *)KASAN_SHADOW_START,
-				    (void *)kasan_mem_to_shadow((void *)
-								VMEMMAP_END));
 	if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
 		kasan_shallow_populate(
 			(void *)kasan_mem_to_shadow((void *)VMALLOC_START),
 			(void *)kasan_mem_to_shadow((void *)VMALLOC_END));
-	else
-		kasan_populate_early_shadow(
-			(void *)kasan_mem_to_shadow((void *)VMALLOC_START),
-			(void *)kasan_mem_to_shadow((void *)VMALLOC_END));
 
 	/* Populate the linear mapping */
 	for_each_mem_range(i, &p_start, &p_end) {