tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
kselftest: arm64: Add BTI tests
Add some tests that verify that BTI functions correctly for static binaries
built with and without BTI support, verifying that SIGILL is generated when
expected and is not generated in other situations.
Since BTI support is still being rolled out in distributions these tests
are built entirely free standing, no libc support is used at all so none
of the standard helper functions for kselftest can be used and we open
code everything. This also means we aren't testing the kernel support for
the dynamic linker, though the test program can be readily adapted for
that once it becomes something that we can reliably build and run.
These tests were originally written by Dave Martin, I've adapted them for
kselftest, mainly around the build system and the output format.
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20210309193731.57247-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
authored by
Mark Brown
and committed by
Catalin Marinas
314bcbf0
75347add
+637
-1
+1
-1
tools/testing/selftests/arm64/Makefile
+1
-1
tools/testing/selftests/arm64/Makefile
+61
tools/testing/selftests/arm64/bti/Makefile
+61
tools/testing/selftests/arm64/bti/Makefile
···
1
+
# SPDX-License-Identifier: GPL-2.0
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TEST_GEN_PROGS := btitest nobtitest
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PROGS := $(patsubst %,gen/%,$(TEST_GEN_PROGS))
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# These tests are built as freestanding binaries since otherwise BTI
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# support in ld.so is required which is not currently widespread; when
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# it is available it will still be useful to test this separately as the
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# cases for statically linked and dynamically lined binaries are
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# slightly different.
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CFLAGS_NOBTI = -DBTI=0
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CFLAGS_BTI = -mbranch-protection=standard -DBTI=1
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CFLAGS_COMMON = -ffreestanding -Wall -Wextra $(CFLAGS)
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+
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BTI_CC_COMMAND = $(CC) $(CFLAGS_BTI) $(CFLAGS_COMMON) -c -o $@ $<
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NOBTI_CC_COMMAND = $(CC) $(CFLAGS_NOBTI) $(CFLAGS_COMMON) -c -o $@ $<
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+
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%-bti.o: %.c
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$(BTI_CC_COMMAND)
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+
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%-bti.o: %.S
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$(BTI_CC_COMMAND)
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+
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%-nobti.o: %.c
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$(NOBTI_CC_COMMAND)
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%-nobti.o: %.S
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$(NOBTI_CC_COMMAND)
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+
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BTI_OBJS = \
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test-bti.o \
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signal-bti.o \
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start-bti.o \
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syscall-bti.o \
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system-bti.o \
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teststubs-bti.o \
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trampoline-bti.o
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gen/btitest: $(BTI_OBJS)
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$(CC) $(CFLAGS_BTI) $(CFLAGS_COMMON) -nostdlib -o $@ $^
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+
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NOBTI_OBJS = \
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test-nobti.o \
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signal-nobti.o \
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start-nobti.o \
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syscall-nobti.o \
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system-nobti.o \
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teststubs-nobti.o \
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trampoline-nobti.o
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gen/nobtitest: $(NOBTI_OBJS)
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$(CC) $(CFLAGS_BTI) $(CFLAGS_COMMON) -nostdlib -o $@ $^
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+
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# Including KSFT lib.mk here will also mangle the TEST_GEN_PROGS list
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# to account for any OUTPUT target-dirs optionally provided by
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# the toplevel makefile
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include ../../lib.mk
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$(TEST_GEN_PROGS): $(PROGS)
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cp $(PROGS) $(OUTPUT)/
+80
tools/testing/selftests/arm64/bti/assembler.h
+80
tools/testing/selftests/arm64/bti/assembler.h
···
1
+
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2019 Arm Limited
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* Original author: Dave Martin <Dave.Martin@arm.com>
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*/
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#ifndef ASSEMBLER_H
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#define ASSEMBLER_H
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#define NT_GNU_PROPERTY_TYPE_0 5
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#define GNU_PROPERTY_AARCH64_FEATURE_1_AND 0xc0000000
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/* Bits for GNU_PROPERTY_AARCH64_FEATURE_1_BTI */
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#define GNU_PROPERTY_AARCH64_FEATURE_1_BTI (1U << 0)
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#define GNU_PROPERTY_AARCH64_FEATURE_1_PAC (1U << 1)
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.macro startfn name:req
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.globl \name
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\name:
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.macro endfn
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.size \name, . - \name
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.type \name, @function
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.purgem endfn
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.endm
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.endm
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+
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.macro emit_aarch64_feature_1_and
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.pushsection .note.gnu.property, "a"
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.align 3
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.long 2f - 1f
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.long 6f - 3f
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.long NT_GNU_PROPERTY_TYPE_0
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1: .string "GNU"
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2:
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.align 3
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3: .long GNU_PROPERTY_AARCH64_FEATURE_1_AND
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.long 5f - 4f
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4:
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#if BTI
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.long GNU_PROPERTY_AARCH64_FEATURE_1_PAC | \
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GNU_PROPERTY_AARCH64_FEATURE_1_BTI
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#else
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.long 0
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#endif
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5:
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.align 3
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6:
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.popsection
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.endm
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+
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.macro paciasp
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hint 0x19
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.endm
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+
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.macro autiasp
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hint 0x1d
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.endm
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+
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.macro __bti_
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hint 0x20
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.endm
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+
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.macro __bti_c
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hint 0x22
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.endm
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+
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.macro __bti_j
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hint 0x24
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.endm
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+
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.macro __bti_jc
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hint 0x26
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.endm
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+
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.macro bti what=
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__bti_\what
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.endm
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#endif /* ! ASSEMBLER_H */
+23
tools/testing/selftests/arm64/bti/btitest.h
+23
tools/testing/selftests/arm64/bti/btitest.h
···
1
+
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2019 Arm Limited
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* Original author: Dave Martin <Dave.Martin@arm.com>
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*/
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+
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#ifndef BTITEST_H
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#define BTITEST_H
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/* Trampolines for calling the test stubs: */
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void call_using_br_x0(void (*)(void));
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void call_using_br_x16(void (*)(void));
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void call_using_blr(void (*)(void));
14
+
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/* Test stubs: */
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void nohint_func(void);
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void bti_none_func(void);
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void bti_c_func(void);
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void bti_j_func(void);
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void bti_jc_func(void);
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void paciasp_func(void);
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#endif /* !BTITEST_H */
+21
tools/testing/selftests/arm64/bti/compiler.h
+21
tools/testing/selftests/arm64/bti/compiler.h
···
1
+
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2019 Arm Limited
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* Original author: Dave Martin <Dave.Martin@arm.com>
5
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*/
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#ifndef COMPILER_H
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#define COMPILER_H
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#define __always_unused __attribute__((__unused__))
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#define __noreturn __attribute__((__noreturn__))
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#define __unreachable() __builtin_unreachable()
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/* curse(e) has value e, but the compiler cannot assume so */
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#define curse(e) ({ \
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__typeof__(e) __curse_e = (e); \
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asm ("" : "+r" (__curse_e)); \
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__curse_e; \
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})
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#endif /* ! COMPILER_H */
+37
tools/testing/selftests/arm64/bti/signal.c
+37
tools/testing/selftests/arm64/bti/signal.c
···
1
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2019 Arm Limited
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* Original author: Dave Martin <Dave.Martin@arm.com>
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*/
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#include "system.h"
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#include "signal.h"
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int sigemptyset(sigset_t *s)
11
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{
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unsigned int i;
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for (i = 0; i < _NSIG_WORDS; ++i)
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s->sig[i] = 0;
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return 0;
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}
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int sigaddset(sigset_t *s, int n)
21
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{
22
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if (n < 1 || n > _NSIG)
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return -EINVAL;
24
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25
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s->sig[(n - 1) / _NSIG_BPW] |= 1UL << (n - 1) % _NSIG_BPW;
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return 0;
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}
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int sigaction(int n, struct sigaction *sa, const struct sigaction *old)
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{
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return syscall(__NR_rt_sigaction, n, sa, old, sizeof(sa->sa_mask));
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}
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int sigprocmask(int how, const sigset_t *mask, sigset_t *old)
35
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{
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return syscall(__NR_rt_sigprocmask, how, mask, old, sizeof(*mask));
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}
+21
tools/testing/selftests/arm64/bti/signal.h
+21
tools/testing/selftests/arm64/bti/signal.h
···
1
+
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2019 Arm Limited
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* Original author: Dave Martin <Dave.Martin@arm.com>
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*/
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#ifndef SIGNAL_H
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#define SIGNAL_H
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#include <linux/signal.h>
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#include "system.h"
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typedef __sighandler_t sighandler_t;
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+
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int sigemptyset(sigset_t *s);
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int sigaddset(sigset_t *s, int n);
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int sigaction(int n, struct sigaction *sa, const struct sigaction *old);
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int sigprocmask(int how, const sigset_t *mask, sigset_t *old);
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#endif /* ! SIGNAL_H */
+14
tools/testing/selftests/arm64/bti/start.S
+14
tools/testing/selftests/arm64/bti/start.S
+23
tools/testing/selftests/arm64/bti/syscall.S
+23
tools/testing/selftests/arm64/bti/syscall.S
···
1
+
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2019 Arm Limited
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* Original author: Dave Martin <Dave.Martin@arm.com>
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*/
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#include "assembler.h"
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startfn syscall
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bti c
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mov w8, w0
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mov x0, x1
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mov x1, x2
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mov x2, x3
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mov x3, x4
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mov x4, x5
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mov x5, x6
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mov x6, x7
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svc #0
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ret
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endfn
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+
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emit_aarch64_feature_1_and
+22
tools/testing/selftests/arm64/bti/system.c
+22
tools/testing/selftests/arm64/bti/system.c
···
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2019 Arm Limited
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* Original author: Dave Martin <Dave.Martin@arm.com>
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*/
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#include "system.h"
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#include <asm/unistd.h>
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#include "compiler.h"
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void __noreturn exit(int n)
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{
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syscall(__NR_exit, n);
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__unreachable();
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}
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ssize_t write(int fd, const void *buf, size_t size)
20
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{
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return syscall(__NR_write, fd, buf, size);
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}
+28
tools/testing/selftests/arm64/bti/system.h
+28
tools/testing/selftests/arm64/bti/system.h
···
1
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2019 Arm Limited
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* Original author: Dave Martin <Dave.Martin@arm.com>
5
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*/
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#ifndef SYSTEM_H
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#define SYSTEM_H
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#include <linux/types.h>
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#include <linux/stddef.h>
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typedef __kernel_size_t size_t;
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typedef __kernel_ssize_t ssize_t;
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#include <linux/errno.h>
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#include <asm/hwcap.h>
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#include <asm/ptrace.h>
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#include <asm/unistd.h>
20
+
21
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#include "compiler.h"
22
+
23
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long syscall(int nr, ...);
24
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25
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void __noreturn exit(int n);
26
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ssize_t write(int fd, const void *buf, size_t size);
27
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28
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#endif /* ! SYSTEM_H */
+234
tools/testing/selftests/arm64/bti/test.c
+234
tools/testing/selftests/arm64/bti/test.c
···
1
+
// SPDX-License-Identifier: GPL-2.0
2
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/*
3
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* Copyright (C) 2019,2021 Arm Limited
4
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* Original author: Dave Martin <Dave.Martin@arm.com>
5
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*/
6
+
7
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#include "system.h"
8
+
9
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#include <linux/errno.h>
10
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#include <linux/auxvec.h>
11
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#include <linux/signal.h>
12
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#include <asm/sigcontext.h>
13
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#include <asm/ucontext.h>
14
+
15
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typedef struct ucontext ucontext_t;
16
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17
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#include "btitest.h"
18
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#include "compiler.h"
19
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#include "signal.h"
20
+
21
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#define EXPECTED_TESTS 18
22
+
23
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static volatile unsigned int test_num = 1;
24
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static unsigned int test_passed;
25
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static unsigned int test_failed;
26
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static unsigned int test_skipped;
27
+
28
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static void fdputs(int fd, const char *str)
29
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{
30
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size_t len = 0;
31
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const char *p = str;
32
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33
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while (*p++)
34
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++len;
35
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36
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write(fd, str, len);
37
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}
38
+
39
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static void putstr(const char *str)
40
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{
41
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fdputs(1, str);
42
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}
43
+
44
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static void putnum(unsigned int num)
45
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{
46
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char c;
47
+
48
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if (num / 10)
49
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putnum(num / 10);
50
+
51
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c = '0' + (num % 10);
52
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write(1, &c, 1);
53
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}
54
+
55
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#define puttestname(test_name, trampoline_name) do { \
56
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putstr(test_name); \
57
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putstr("/"); \
58
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putstr(trampoline_name); \
59
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} while (0)
60
+
61
+
void print_summary(void)
62
+
{
63
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putstr("# Totals: pass:");
64
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putnum(test_passed);
65
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putstr(" fail:");
66
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putnum(test_failed);
67
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putstr(" xfail:0 xpass:0 skip:");
68
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putnum(test_skipped);
69
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putstr(" error:0\n");
70
+
}
71
+
72
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static const char *volatile current_test_name;
73
+
static const char *volatile current_trampoline_name;
74
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static volatile int sigill_expected, sigill_received;
75
+
76
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static void handler(int n, siginfo_t *si __always_unused,
77
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void *uc_ __always_unused)
78
+
{
79
+
ucontext_t *uc = uc_;
80
+
81
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putstr("# \t[SIGILL in ");
82
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puttestname(current_test_name, current_trampoline_name);
83
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putstr(", BTYPE=");
84
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write(1, &"00011011"[((uc->uc_mcontext.pstate & PSR_BTYPE_MASK)
85
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>> PSR_BTYPE_SHIFT) * 2], 2);
86
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if (!sigill_expected) {
87
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putstr("]\n");
88
+
putstr("not ok ");
89
+
putnum(test_num);
90
+
putstr(" ");
91
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puttestname(current_test_name, current_trampoline_name);
92
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putstr("(unexpected SIGILL)\n");
93
+
print_summary();
94
+
exit(128 + n);
95
+
}
96
+
97
+
putstr(" (expected)]\n");
98
+
sigill_received = 1;
99
+
/* zap BTYPE so that resuming the faulting code will work */
100
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uc->uc_mcontext.pstate &= ~PSR_BTYPE_MASK;
101
+
}
102
+
103
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static int skip_all;
104
+
105
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static void __do_test(void (*trampoline)(void (*)(void)),
106
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void (*fn)(void),
107
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const char *trampoline_name,
108
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const char *name,
109
+
int expect_sigill)
110
+
{
111
+
if (skip_all) {
112
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test_skipped++;
113
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putstr("ok ");
114
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putnum(test_num);
115
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putstr(" ");
116
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puttestname(name, trampoline_name);
117
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putstr(" # SKIP\n");
118
+
119
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return;
120
+
}
121
+
122
+
/* Branch Target exceptions should only happen in BTI binaries: */
123
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if (!BTI)
124
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expect_sigill = 0;
125
+
126
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sigill_expected = expect_sigill;
127
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sigill_received = 0;
128
+
current_test_name = name;
129
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current_trampoline_name = trampoline_name;
130
+
131
+
trampoline(fn);
132
+
133
+
if (expect_sigill && !sigill_received) {
134
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putstr("not ok ");
135
+
test_failed++;
136
+
} else {
137
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putstr("ok ");
138
+
test_passed++;
139
+
}
140
+
putnum(test_num++);
141
+
putstr(" ");
142
+
puttestname(name, trampoline_name);
143
+
putstr("\n");
144
+
}
145
+
146
+
#define do_test(expect_sigill_br_x0, \
147
+
expect_sigill_br_x16, \
148
+
expect_sigill_blr, \
149
+
name) \
150
+
do { \
151
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__do_test(call_using_br_x0, name, "call_using_br_x0", #name, \
152
+
expect_sigill_br_x0); \
153
+
__do_test(call_using_br_x16, name, "call_using_br_x16", #name, \
154
+
expect_sigill_br_x16); \
155
+
__do_test(call_using_blr, name, "call_using_blr", #name, \
156
+
expect_sigill_blr); \
157
+
} while (0)
158
+
159
+
void start(int *argcp)
160
+
{
161
+
struct sigaction sa;
162
+
void *const *p;
163
+
const struct auxv_entry {
164
+
unsigned long type;
165
+
unsigned long val;
166
+
} *auxv;
167
+
unsigned long hwcap = 0, hwcap2 = 0;
168
+
169
+
putstr("TAP version 13\n");
170
+
putstr("1..");
171
+
putnum(EXPECTED_TESTS);
172
+
putstr("\n");
173
+
174
+
/* Gross hack for finding AT_HWCAP2 from the initial process stack: */
175
+
p = (void *const *)argcp + 1 + *argcp + 1; /* start of environment */
176
+
/* step over environment */
177
+
while (*p++)
178
+
;
179
+
for (auxv = (const struct auxv_entry *)p; auxv->type != AT_NULL; ++auxv) {
180
+
switch (auxv->type) {
181
+
case AT_HWCAP:
182
+
hwcap = auxv->val;
183
+
break;
184
+
case AT_HWCAP2:
185
+
hwcap2 = auxv->val;
186
+
break;
187
+
default:
188
+
break;
189
+
}
190
+
}
191
+
192
+
if (hwcap & HWCAP_PACA)
193
+
putstr("# HWCAP_PACA present\n");
194
+
else
195
+
putstr("# HWCAP_PACA not present\n");
196
+
197
+
if (hwcap2 & HWCAP2_BTI) {
198
+
putstr("# HWCAP2_BTI present\n");
199
+
if (!(hwcap & HWCAP_PACA))
200
+
putstr("# Bad hardware? Expect problems.\n");
201
+
} else {
202
+
putstr("# HWCAP2_BTI not present\n");
203
+
skip_all = 1;
204
+
}
205
+
206
+
putstr("# Test binary");
207
+
if (!BTI)
208
+
putstr(" not");
209
+
putstr(" built for BTI\n");
210
+
211
+
sa.sa_handler = (sighandler_t)(void *)handler;
212
+
sa.sa_flags = SA_SIGINFO;
213
+
sigemptyset(&sa.sa_mask);
214
+
sigaction(SIGILL, &sa, NULL);
215
+
sigaddset(&sa.sa_mask, SIGILL);
216
+
sigprocmask(SIG_UNBLOCK, &sa.sa_mask, NULL);
217
+
218
+
do_test(1, 1, 1, nohint_func);
219
+
do_test(1, 1, 1, bti_none_func);
220
+
do_test(1, 0, 0, bti_c_func);
221
+
do_test(0, 0, 1, bti_j_func);
222
+
do_test(0, 0, 0, bti_jc_func);
223
+
do_test(1, 0, 0, paciasp_func);
224
+
225
+
print_summary();
226
+
227
+
if (test_num - 1 != EXPECTED_TESTS)
228
+
putstr("# WARNING - EXPECTED TEST COUNT WRONG\n");
229
+
230
+
if (test_failed)
231
+
exit(1);
232
+
else
233
+
exit(0);
234
+
}
+39
tools/testing/selftests/arm64/bti/teststubs.S
+39
tools/testing/selftests/arm64/bti/teststubs.S
···
1
+
/* SPDX-License-Identifier: GPL-2.0 */
2
+
/*
3
+
* Copyright (C) 2019 Arm Limited
4
+
* Original author: Dave Martin <Dave.Martin@arm.com>
5
+
*/
6
+
7
+
#include "assembler.h"
8
+
9
+
startfn bti_none_func
10
+
bti
11
+
ret
12
+
endfn
13
+
14
+
startfn bti_c_func
15
+
bti c
16
+
ret
17
+
endfn
18
+
19
+
startfn bti_j_func
20
+
bti j
21
+
ret
22
+
endfn
23
+
24
+
startfn bti_jc_func
25
+
bti jc
26
+
ret
27
+
endfn
28
+
29
+
startfn paciasp_func
30
+
paciasp
31
+
autiasp
32
+
ret
33
+
endfn
34
+
35
+
startfn nohint_func
36
+
ret
37
+
endfn
38
+
39
+
emit_aarch64_feature_1_and
+29
tools/testing/selftests/arm64/bti/trampoline.S
+29
tools/testing/selftests/arm64/bti/trampoline.S
···
1
+
/* SPDX-License-Identifier: GPL-2.0 */
2
+
/*
3
+
* Copyright (C) 2019 Arm Limited
4
+
* Original author: Dave Martin <Dave.Martin@arm.com>
5
+
*/
6
+
7
+
#include "assembler.h"
8
+
9
+
startfn call_using_br_x0
10
+
bti c
11
+
br x0
12
+
endfn
13
+
14
+
startfn call_using_br_x16
15
+
bti c
16
+
mov x16, x0
17
+
br x16
18
+
endfn
19
+
20
+
startfn call_using_blr
21
+
paciasp
22
+
stp x29, x30, [sp, #-16]!
23
+
blr x0
24
+
ldp x29, x30, [sp], #16
25
+
autiasp
26
+
ret
27
+
endfn
28
+
29
+
emit_aarch64_feature_1_and