Merge tag 'clang-features-v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull clang feature updates from Kees Cook:
- Add CC_HAS_NO_PROFILE_FN_ATTR in preparation for PGO support in the
face of the noinstr attribute, paving the way for PGO and fixing
GCOV. (Nick Desaulniers)
- x86_64 LTO coverage is expanded to 32-bit x86. (Nathan Chancellor)
- Small fixes to CFI. (Mark Rutland, Nathan Chancellor)
* tag 'clang-features-v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
qemu_fw_cfg: Make fw_cfg_rev_attr a proper kobj_attribute
Kconfig: Introduce ARCH_WANTS_NO_INSTR and CC_HAS_NO_PROFILE_FN_ATTR
compiler_attributes.h: cleanups for GCC 4.9+
compiler_attributes.h: define __no_profile, add to noinstr
x86, lto: Enable Clang LTO for 32-bit as well
CFI: Move function_nocfi() into compiler.h
MAINTAINERS: Add Clang CFI section
diff --git a/MAINTAINERS b/MAINTAINERS
index 9999ae6..f4af84a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4447,6 +4447,18 @@
F: scripts/clang-tools/
K: \b(?i:clang|llvm)\b
+CLANG CONTROL FLOW INTEGRITY SUPPORT
+M: Sami Tolvanen <samitolvanen@google.com>
+M: Kees Cook <keescook@chromium.org>
+R: Nathan Chancellor <nathan@kernel.org>
+R: Nick Desaulniers <ndesaulniers@google.com>
+L: clang-built-linux@googlegroups.com
+S: Supported
+B: https://github.com/ClangBuiltLinux/linux/issues
+T: git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/clang/features
+F: include/linux/cfi.h
+F: kernel/cfi.c
+
CLEANCACHE API
M: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
L: linux-kernel@vger.kernel.org
diff --git a/arch/Kconfig b/arch/Kconfig
index c45b770..129df49 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -285,6 +285,13 @@
config ARCH_WANTS_DYNAMIC_TASK_STRUCT
bool
+config ARCH_WANTS_NO_INSTR
+ bool
+ help
+ An architecture should select this if the noinstr macro is being used on
+ functions to denote that the toolchain should avoid instrumenting such
+ functions and is required for correctness.
+
config ARCH_32BIT_OFF_T
bool
depends on !64BIT
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a6a09cb..be90838 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -93,6 +93,7 @@
select ARCH_WANT_FRAME_POINTERS
select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)
select ARCH_WANT_LD_ORPHAN_WARN
+ select ARCH_WANTS_NO_INSTR
select ARCH_HAS_UBSAN_SANITIZE_ALL
select ARM_AMBA
select ARM_ARCH_TIMER
diff --git a/arch/arm64/include/asm/compiler.h b/arch/arm64/include/asm/compiler.h
index 6fb2e6b..dc3ea40 100644
--- a/arch/arm64/include/asm/compiler.h
+++ b/arch/arm64/include/asm/compiler.h
@@ -23,4 +23,20 @@
#define __builtin_return_address(val) \
(void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val)))
+#ifdef CONFIG_CFI_CLANG
+/*
+ * With CONFIG_CFI_CLANG, the compiler replaces function address
+ * references with the address of the function's CFI jump table
+ * entry. The function_nocfi macro always returns the address of the
+ * actual function instead.
+ */
+#define function_nocfi(x) ({ \
+ void *addr; \
+ asm("adrp %0, " __stringify(x) "\n\t" \
+ "add %0, %0, :lo12:" __stringify(x) \
+ : "=r" (addr)); \
+ addr; \
+})
+#endif
+
#endif /* __ASM_COMPILER_H */
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 7b36096..1a35a44 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -321,22 +321,6 @@ static inline void *phys_to_virt(phys_addr_t x)
#define virt_to_pfn(x) __phys_to_pfn(__virt_to_phys((unsigned long)(x)))
#define sym_to_pfn(x) __phys_to_pfn(__pa_symbol(x))
-#ifdef CONFIG_CFI_CLANG
-/*
- * With CONFIG_CFI_CLANG, the compiler replaces function address
- * references with the address of the function's CFI jump table
- * entry. The function_nocfi macro always returns the address of the
- * actual function instead.
- */
-#define function_nocfi(x) ({ \
- void *addr; \
- asm("adrp %0, " __stringify(x) "\n\t" \
- "add %0, %0, :lo12:" __stringify(x) \
- : "=r" (addr)); \
- addr; \
-})
-#endif
-
/*
* virt_to_page(x) convert a _valid_ virtual address to struct page *
* virt_addr_valid(x) indicates whether a virtual address is valid
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 707afbc..a499716 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -117,6 +117,7 @@
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_CMPXCHG_LOCKREF
select ARCH_WANTS_DYNAMIC_TASK_STRUCT
+ select ARCH_WANTS_NO_INSTR
select ARCH_WANT_DEFAULT_BPF_JIT
select ARCH_WANT_IPC_PARSE_VERSION
select BUILDTIME_TABLE_SORT
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 49ffb69..867e793 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -103,8 +103,8 @@
select ARCH_SUPPORTS_DEBUG_PAGEALLOC
select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
- select ARCH_SUPPORTS_LTO_CLANG if X86_64
- select ARCH_SUPPORTS_LTO_CLANG_THIN if X86_64
+ select ARCH_SUPPORTS_LTO_CLANG
+ select ARCH_SUPPORTS_LTO_CLANG_THIN
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_MEMTEST
select ARCH_USE_QUEUED_RWLOCKS
@@ -113,6 +113,7 @@
select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
select ARCH_WANTS_DYNAMIC_TASK_STRUCT
+ select ARCH_WANTS_NO_INSTR
select ARCH_WANT_HUGE_PMD_SHARE
select ARCH_WANT_LD_ORPHAN_WARN
select ARCH_WANTS_THP_SWAP if X86_64
diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 0078260..172c751 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -299,15 +299,13 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev)
return 0;
}
-static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
+static ssize_t fw_cfg_showrev(struct kobject *k, struct kobj_attribute *a,
+ char *buf)
{
return sprintf(buf, "%u\n", fw_cfg_rev);
}
-static const struct {
- struct attribute attr;
- ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);
-} fw_cfg_rev_attr = {
+static const struct kobj_attribute fw_cfg_rev_attr = {
.attr = { .name = "rev", .mode = S_IRUSR },
.show = fw_cfg_showrev,
};
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 7704790..b67261a 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -219,6 +219,16 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
__v; \
})
+/*
+ * With CONFIG_CFI_CLANG, the compiler replaces function addresses in
+ * instrumented C code with jump table addresses. Architectures that
+ * support CFI can define this macro to return the actual function address
+ * when needed.
+ */
+#ifndef function_nocfi
+#define function_nocfi(x) (x)
+#endif
+
#endif /* __KERNEL__ */
/*
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index 183ddd5..2487be0 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -27,15 +27,16 @@
*/
#ifndef __has_attribute
# define __has_attribute(x) __GCC4_has_attribute_##x
-# define __GCC4_has_attribute___assume_aligned__ (__GNUC_MINOR__ >= 9)
+# define __GCC4_has_attribute___assume_aligned__ 1
# define __GCC4_has_attribute___copy__ 0
# define __GCC4_has_attribute___designated_init__ 0
# define __GCC4_has_attribute___externally_visible__ 1
# define __GCC4_has_attribute___no_caller_saved_registers__ 0
# define __GCC4_has_attribute___noclone__ 1
+# define __GCC4_has_attribute___no_profile_instrument_function__ 0
# define __GCC4_has_attribute___nonstring__ 0
-# define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
-# define __GCC4_has_attribute___no_sanitize_undefined__ (__GNUC_MINOR__ >= 9)
+# define __GCC4_has_attribute___no_sanitize_address__ 1
+# define __GCC4_has_attribute___no_sanitize_undefined__ 1
# define __GCC4_has_attribute___fallthrough__ 0
#endif
@@ -239,6 +240,18 @@
#endif
/*
+ * Optional: only supported since GCC >= 7.1, clang >= 13.0.
+ *
+ * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute
+ * clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function
+ */
+#if __has_attribute(__no_profile_instrument_function__)
+# define __no_profile __attribute__((__no_profile_instrument_function__))
+#else
+# define __no_profile
+#endif
+
+/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn
* clang: https://clang.llvm.org/docs/AttributeReference.html#id1
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index d29bda7..d509169 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -210,7 +210,7 @@ struct ftrace_likely_data {
/* Section for code which can't be instrumented at all */
#define noinstr \
noinline notrace __attribute((__section__(".noinstr.text"))) \
- __no_kcsan __no_sanitize_address
+ __no_kcsan __no_sanitize_address __no_profile
#endif /* __KERNEL__ */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6d0f827..7ec25dd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -125,16 +125,6 @@ extern int mmap_rnd_compat_bits __read_mostly;
#endif
/*
- * With CONFIG_CFI_CLANG, the compiler replaces function addresses in
- * instrumented C code with jump table addresses. Architectures that
- * support CFI can define this macro to return the actual function address
- * when needed.
- */
-#ifndef function_nocfi
-#define function_nocfi(x) (x)
-#endif
-
-/*
* To prevent common memory management code establishing
* a zero page mapping on a read fault.
* This macro should be defined within <asm/pgtable.h>.
diff --git a/init/Kconfig b/init/Kconfig
index a61c920..55f9f77 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -83,6 +83,9 @@
config CC_HAS_ASM_INLINE
def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
+config CC_HAS_NO_PROFILE_FN_ATTR
+ def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
+
config CONSTRUCTORS
bool
diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
index 58f87a3..0534471 100644
--- a/kernel/gcov/Kconfig
+++ b/kernel/gcov/Kconfig
@@ -5,6 +5,7 @@
bool "Enable gcov-based kernel profiling"
depends on DEBUG_FS
depends on !CC_IS_CLANG || CLANG_VERSION >= 110000
+ depends on !ARCH_WANTS_NO_INSTR || CC_HAS_NO_PROFILE_FN_ATTR
select CONSTRUCTORS
default n
help
