Commit 2c9bd9d8 authored by Will Deacon's avatar Will Deacon
Browse files

Merge branch 'for-next/kasan' into for-next/core 

Optimise out-of-line KASAN checking when using software tagging.

* for-next/kasan:
  kasan: arm64: support specialized outlined tag mismatch checks
parents 181a1269 1cbdf60b

arch/arm64/include/asm/asm-prototypes.h

+6 −0
Original line number Diff line number Diff line
@@ -23,4 +23,10 @@ long long __ashlti3(long long a, int b); 
long long __ashrti3(long long a, int b);

long long __lshrti3(long long a, int b);



/*

 * This function uses a custom calling convention and cannot be called from C so

 * this prototype is not entirely accurate.

 */

void __hwasan_tag_mismatch(unsigned long addr, unsigned long access_info);



#endif /* __ASM_PROTOTYPES_H */

arch/arm64/include/asm/module.lds.h

+15 −2
Original line number Diff line number Diff line 
#ifdef CONFIG_ARM64_MODULE_PLTS

SECTIONS {

#ifdef CONFIG_ARM64_MODULE_PLTS

	.plt 0 (NOLOAD) : { BYTE(0) }

	.init.plt 0 (NOLOAD) : { BYTE(0) }

	.text.ftrace_trampoline 0 (NOLOAD) : { BYTE(0) }

}

#endif



#ifdef CONFIG_KASAN_SW_TAGS

	/*

	 * Outlined checks go into comdat-deduplicated sections named .text.hot.

	 * Because they are in comdats they are not combined by the linker and

	 * we otherwise end up with multiple sections with the same .text.hot

	 * name in the .ko file. The kernel module loader warns if it sees

	 * multiple sections with the same name so we use this sections

	 * directive to force them into a single section and silence the

	 * warning.

	 */

	.text.hot : { *(.text.hot) }

#endif

}

arch/arm64/lib/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -18,3 +18,5 @@ obj-$(CONFIG_CRC32) += crc32.o 
obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o



obj-$(CONFIG_ARM64_MTE) += mte.o



obj-$(CONFIG_KASAN_SW_TAGS) += kasan_sw_tags.o

arch/arm64/lib/kasan_sw_tags.S

0 → 100644
+76 −0
Original line number Diff line number Diff line 
/* 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)

#ifdef BTI_C

	BTI_C

#endif

	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)

mm/kasan/sw_tags.c

+7 −0
Original line number Diff line number Diff line
@@ -207,3 +207,10 @@ struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, 


	return &alloc_meta->free_track[i];

}



void kasan_tag_mismatch(unsigned long addr, unsigned long access_info,

			unsigned long ret_ip)

{

	kasan_report(addr, 1 << (access_info & 0xf), access_info & 0x10,

		     ret_ip);

}