diff options
Diffstat (limited to 'arch/arm64/lib/kasan_sw_tags.S')
-rw-r--r-- | arch/arm64/lib/kasan_sw_tags.S | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/arch/arm64/lib/kasan_sw_tags.S b/arch/arm64/lib/kasan_sw_tags.S new file mode 100644 index 0000000000..20784ce75d --- /dev/null +++ b/arch/arm64/lib/kasan_sw_tags.S @@ -0,0 +1,74 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2020 Google LLC + */ + +#include <linux/linkage.h> +#include <asm/assembler.h> + +/* + * Report a tag mismatch detected by tag-based KASAN. + * + * A compiler-generated thunk calls this with a non-AAPCS calling + * convention. Upon entry to this function, registers are as follows: + * + * x0: fault address (see below for restore) + * x1: fault description (see below for restore) + * x2 to x15: callee-saved + * x16 to x17: safe to clobber + * x18 to x30: callee-saved + * sp: pre-decremented by 256 bytes (see below for restore) + * + * The caller has decremented the SP by 256 bytes, and created a + * structure on the stack as follows: + * + * sp + 0..15: x0 and x1 to be restored + * sp + 16..231: free for use + * sp + 232..247: x29 and x30 (same as in GPRs) + * sp + 248..255: free for use + * + * Note that this is not a struct pt_regs. + * + * To call a regular AAPCS function we must save x2 to x15 (which we can + * store in the gaps), and create a frame record (for which we can use + * x29 and x30 spilled by the caller as those match the GPRs). + * + * The caller expects x0 and x1 to be restored from the structure, and + * for the structure to be removed from the stack (i.e. the SP must be + * incremented by 256 prior to return). + */ +SYM_CODE_START(__hwasan_tag_mismatch) + bti c + add x29, sp, #232 + stp x2, x3, [sp, #8 * 2] + stp x4, x5, [sp, #8 * 4] + stp x6, x7, [sp, #8 * 6] + stp x8, x9, [sp, #8 * 8] + stp x10, x11, [sp, #8 * 10] + stp x12, x13, [sp, #8 * 12] + stp x14, x15, [sp, #8 * 14] +#ifndef CONFIG_SHADOW_CALL_STACK + str x18, [sp, #8 * 18] +#endif + + mov x2, x30 + bl kasan_tag_mismatch + + ldp x0, x1, [sp] + ldp x2, x3, [sp, #8 * 2] + ldp x4, x5, [sp, #8 * 4] + ldp x6, x7, [sp, #8 * 6] + ldp x8, x9, [sp, #8 * 8] + ldp x10, x11, [sp, #8 * 10] + ldp x12, x13, [sp, #8 * 12] + ldp x14, x15, [sp, #8 * 14] +#ifndef CONFIG_SHADOW_CALL_STACK + ldr x18, [sp, #8 * 18] +#endif + ldp x29, x30, [sp, #8 * 29] + + /* remove the structure from the stack */ + add sp, sp, #256 + ret +SYM_CODE_END(__hwasan_tag_mismatch) +EXPORT_SYMBOL(__hwasan_tag_mismatch) |