Commit 441c63ff authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux 

Pull arm64 fix from Will Deacon:

 - Implement a basic static call trampoline to fix CFI failures with the
   generic implementation

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Use static call trampolines when kCFI is enabled
parents 60d9212c 54ac9ff8

arch/arm64/Kconfig

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@@ -252,6 +252,7 @@ config ARM64 
	select HAVE_RSEQ

	select HAVE_RUST if RUSTC_SUPPORTS_ARM64

	select HAVE_STACKPROTECTOR

	select HAVE_STATIC_CALL if CFI

	select HAVE_SYSCALL_TRACEPOINTS

	select HAVE_KPROBES

	select HAVE_KRETPROBES

arch/arm64/include/asm/static_call.h

0 → 100644
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/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _ASM_STATIC_CALL_H

#define _ASM_STATIC_CALL_H



#define __ARCH_DEFINE_STATIC_CALL_TRAMP(name, target)		    \

	asm("	.pushsection .static_call.text, \"ax\"		\n" \

	    "	.align	4					\n" \

	    "	.globl	" name "				\n" \

	    name ":						\n" \

	    "	hint	34	/* BTI C */			\n" \

	    "	adrp	x16, 1f					\n" \

	    "	ldr	x16, [x16, :lo12:1f]			\n" \

	    "	br	x16					\n" \

	    "	.type	" name ", %function			\n" \

	    "	.size	" name ", . - " name "			\n" \

	    "	.popsection					\n" \

	    "	.pushsection .rodata, \"a\"			\n" \

	    "	.align	3					\n" \

	    "1:	.quad	" target "				\n" \

	    "	.popsection					\n")



#define ARCH_DEFINE_STATIC_CALL_TRAMP(name, func)			\

	__ARCH_DEFINE_STATIC_CALL_TRAMP(STATIC_CALL_TRAMP_STR(name), #func)



#define ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name)			\

	ARCH_DEFINE_STATIC_CALL_TRAMP(name, __static_call_return0)



#define ARCH_DEFINE_STATIC_CALL_RET0_TRAMP(name)			\

	ARCH_DEFINE_STATIC_CALL_TRAMP(name, __static_call_return0)



#endif /* _ASM_STATIC_CALL_H */

arch/arm64/kernel/Makefile

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@@ -46,6 +46,7 @@ obj-$(CONFIG_MODULES) += module.o module-plts.o 
obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o perf_callchain.o

obj-$(CONFIG_HARDLOCKUP_DETECTOR_PERF)	+= watchdog_hld.o

obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o

obj-$(CONFIG_HAVE_STATIC_CALL)		+= static_call.o

obj-$(CONFIG_CPU_PM)			+= sleep.o suspend.o

obj-$(CONFIG_KGDB)			+= kgdb.o

obj-$(CONFIG_EFI)			+= efi.o efi-rt-wrapper.o

arch/arm64/kernel/static_call.c

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// SPDX-License-Identifier: GPL-2.0

#include <linux/static_call.h>

#include <linux/memory.h>

#include <asm/text-patching.h>



void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)

{

	u64 literal;

	int ret;



	if (!func)

		func = __static_call_return0;



	/* decode the instructions to discover the literal address */

	literal = ALIGN_DOWN((u64)tramp + 4, SZ_4K) +

		  aarch64_insn_adrp_get_offset(le32_to_cpup(tramp + 4)) +

		  8 * aarch64_insn_decode_immediate(AARCH64_INSN_IMM_12,

						    le32_to_cpup(tramp + 8));



	ret = aarch64_insn_write_literal_u64((void *)literal, (u64)func);

	WARN_ON_ONCE(ret);

}

EXPORT_SYMBOL_GPL(arch_static_call_transform);

arch/arm64/kernel/vmlinux.lds.S

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@@ -191,6 +191,7 @@ SECTIONS 
			LOCK_TEXT

			KPROBES_TEXT

			HYPERVISOR_TEXT

			STATIC_CALL_TEXT

			*(.gnu.warning)

	}