On Thu, May 14, 2020 at 01:21:42PM +0200, Peter Zijlstra wrote:
> Given the patch below (on top of tglx's entry-v5-the-rest tag); I did
> find that I could actually build alternative.o for gcc-{8,9,10} and
> indeed clang-10. Any earlier gcc (I tried, 5,6,7) does not build:Damn!, I forgot the patch from https://lkml.kernel.org/r/20200513111447.ge3...@hirez.programming.kicks-ass.net With that included, on a GCC-10 KCSAN+UBSAN build, I now get this, and that is very much not okay. This is the thing Will complained about as well I think. Hohumm :-( --- diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index d6d61c4455fa..ba89cabe5fcf 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -28,10 +28,6 @@ KASAN_SANITIZE_dumpstack_$(BITS).o := n KASAN_SANITIZE_stacktrace.o := n KASAN_SANITIZE_paravirt.o := n -# With some compiler versions the generated code results in boot hangs, caused -# by several compilation units. To be safe, disable all instrumentation. -KCSAN_SANITIZE := n - OBJECT_FILES_NON_STANDARD_test_nx.o := y OBJECT_FILES_NON_STANDARD_paravirt_patch.o := y diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 77c83833d91e..06d8db612efc 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -990,7 +990,7 @@ static __always_inline int patch_cmp(const void *key, const void *elt) return 0; } -int noinstr poke_int3_handler(struct pt_regs *regs) +int noinstr __no_kcsan __no_sanitize_address __no_sanitize_undefined poke_int3_handler(struct pt_regs *regs) { struct bp_patching_desc *desc; struct text_poke_loc *tp; diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index 2cb42d8bdedc..c728ae9dcf96 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -15,6 +15,9 @@ /* all clang versions usable with the kernel support KASAN ABI version 5 */ #define KASAN_ABI_VERSION 5 +#define __no_sanitize_undefined \ + __attribute__((no_sanitize("undefined"))) + #if __has_feature(address_sanitizer) || __has_feature(hwaddress_sanitizer) /* Emulate GCC's __SANITIZE_ADDRESS__ flag */ #define __SANITIZE_ADDRESS__ diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 7dd4e0349ef3..8196a121a78e 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -138,6 +138,12 @@ #define KASAN_ABI_VERSION 3 #endif +#if __has_attribute(__no_sanitize_undefined__) +#define __no_sanitize_undefined __attribute__((no_sanitize_undefined)) +#else +#define __no_sanitize_undefined +#endif + #if __has_attribute(__no_sanitize_address__) #define __no_sanitize_address __attribute__((no_sanitize_address)) #else diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 3bb962959d8b..2ea532b19e75 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -241,12 +241,12 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, * atomicity or dependency ordering guarantees. Note that this may result * in tears! */ -#define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x)) +#define __READ_ONCE(x) data_race((*(const volatile __unqual_scalar_typeof(x) *)&(x))) #define __READ_ONCE_SCALAR(x) \ ({ \ typeof(x) *__xp = &(x); \ - __unqual_scalar_typeof(x) __x = data_race(__READ_ONCE(*__xp)); \ + __unqual_scalar_typeof(x) __x = __READ_ONCE(*__xp); \ kcsan_check_atomic_read(__xp, sizeof(*__xp)); \ smp_read_barrier_depends(); \ (typeof(x))__x; \ @@ -260,14 +260,14 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, #define __WRITE_ONCE(x, val) \ do { \ - *(volatile typeof(x) *)&(x) = (val); \ + data_race(*(volatile typeof(x) *)&(x) = (val)); \ } while (0) #define __WRITE_ONCE_SCALAR(x, val) \ do { \ typeof(x) *__xp = &(x); \ kcsan_check_atomic_write(__xp, sizeof(*__xp)); \ - data_race(({ __WRITE_ONCE(*__xp, val); 0; })); \ + __WRITE_ONCE(*__xp, val); \ } while (0) #define WRITE_ONCE(x, val) \ --- 0000 0000000000000000 <poke_int3_handler>: 0000 0: 41 55 push %r13 0002 2: 41 54 push %r12 0004 4: 55 push %rbp 0005 5: 53 push %rbx 0006 6: 48 83 ec 10 sub $0x10,%rsp 000a a: 65 48 8b 04 25 28 00 mov %gs:0x28,%rax 0011 11: 00 00 0013 13: 48 89 44 24 08 mov %rax,0x8(%rsp) 0018 18: 31 c0 xor %eax,%eax 001a 1a: f6 87 88 00 00 00 03 testb $0x3,0x88(%rdi) 0021 21: 74 21 je 44 <poke_int3_handler+0x44> 0023 23: 31 c0 xor %eax,%eax 0025 25: 48 8b 4c 24 08 mov 0x8(%rsp),%rcx 002a 2a: 65 48 2b 0c 25 28 00 sub %gs:0x28,%rcx 0031 31: 00 00 0033 33: 0f 85 79 01 00 00 jne 1b2 <poke_int3_handler+0x1b2> 0039 39: 48 83 c4 10 add $0x10,%rsp 003d 3d: 5b pop %rbx 003e 3e: 5d pop %rbp 003f 3f: 41 5c pop %r12 0041 41: 41 5d pop %r13 0043 43: c3 retq 0044 44: 48 89 fb mov %rdi,%rbx 0047 47: e8 00 00 00 00 callq 4c <poke_int3_handler+0x4c> 0048 48: R_X86_64_PLT32 kcsan_disable_current-0x4 004c 4c: 4c 8b 2d 00 00 00 00 mov 0x0(%rip),%r13 # 53 <poke_int3_handler+0x53> 004f 4f: R_X86_64_PC32 .bss+0x101c 0053 53: 48 8d 6c 24 08 lea 0x8(%rsp),%rbp 0058 58: 49 89 e4 mov %rsp,%r12 005b 5b: 48 89 e8 mov %rbp,%rax 005e 5e: 4c 29 e0 sub %r12,%rax 0061 61: 48 83 f8 08 cmp $0x8,%rax 0065 65: 0f 87 4c 01 00 00 ja 1b7 <poke_int3_handler+0x1b7> 006b 6b: 4c 29 e5 sub %r12,%rbp 006e 6e: 4c 89 2c 24 mov %r13,(%rsp) 0072 72: e8 00 00 00 00 callq 77 <poke_int3_handler+0x77> 0073 73: R_X86_64_PLT32 kcsan_enable_current_nowarn-0x4 0077 77: 48 83 fd 08 cmp $0x8,%rbp 007b 7b: 0f 87 53 01 00 00 ja 1d4 <poke_int3_handler+0x1d4> 0081 81: 4c 8b 24 24 mov (%rsp),%r12 0085 85: 4d 85 e4 test %r12,%r12 0088 88: 74 99 je 23 <poke_int3_handler+0x23> 008a 8a: e8 00 00 00 00 callq 8f <poke_int3_handler+0x8f> 008b 8b: R_X86_64_PLT32 kcsan_disable_current-0x4 008f 8f: 4d 8d 6c 24 0c lea 0xc(%r12),%r13 0094 94: 41 8b 6c 24 0c mov 0xc(%r12),%ebp 0099 99: e8 00 00 00 00 callq 9e <poke_int3_handler+0x9e> 009a 9a: R_X86_64_PLT32 kcsan_enable_current_nowarn-0x4 009e 9e: 85 ed test %ebp,%ebp 00a0 a0: 74 81 je 23 <poke_int3_handler+0x23> 00a2 a2: 8d 55 01 lea 0x1(%rbp),%edx 00a5 a5: 89 e8 mov %ebp,%eax 00a7 a7: f0 41 0f b1 55 00 lock cmpxchg %edx,0x0(%r13) 00ad ad: 89 c5 mov %eax,%ebp 00af af: 75 ed jne 9e <poke_int3_handler+0x9e> 00b1 b1: 48 8b bb 80 00 00 00 mov 0x80(%rbx),%rdi 00b8 b8: 49 63 44 24 08 movslq 0x8(%r12),%rax 00bd bd: 49 8b 0c 24 mov (%r12),%rcx 00c1 c1: 48 8d 57 ff lea -0x1(%rdi),%rdx 00c5 c5: 83 f8 01 cmp $0x1,%eax 00c8 c8: 7f 1c jg e6 <poke_int3_handler+0xe6> 00ca ca: 48 63 31 movslq (%rcx),%rsi 00cd cd: 31 c0 xor %eax,%eax 00cf cf: 48 81 c6 00 00 00 00 add $0x0,%rsi 00d2 d2: R_X86_64_32S _stext 00d6 d6: 48 39 f2 cmp %rsi,%rdx 00d9 d9: 74 3c je 117 <poke_int3_handler+0x117> 00db db: f0 41 ff 4c 24 0c lock decl 0xc(%r12) 00e1 e1: e9 3f ff ff ff jmpq 25 <poke_int3_handler+0x25> 00e6 e6: 49 89 c9 mov %rcx,%r9 00e9 e9: 49 89 c0 mov %rax,%r8 00ec ec: 49 d1 e8 shr %r8 00ef ef: 4c 89 c1 mov %r8,%rcx 00f2 f2: 48 c1 e1 04 shl $0x4,%rcx 00f6 f6: 4c 01 c9 add %r9,%rcx 00f9 f9: 48 63 31 movslq (%rcx),%rsi 00fc fc: 48 81 c6 00 00 00 00 add $0x0,%rsi 00ff ff: R_X86_64_32S _stext 0103 103: 48 39 f2 cmp %rsi,%rdx 0106 106: 0f 82 88 00 00 00 jb 194 <poke_int3_handler+0x194> 010c 10c: 0f 87 93 00 00 00 ja 1a5 <poke_int3_handler+0x1a5> 0112 112: 48 85 c9 test %rcx,%rcx 0115 115: 74 28 je 13f <poke_int3_handler+0x13f> 0117 117: 0f b6 41 08 movzbl 0x8(%rcx),%eax 011b 11b: 8d 70 34 lea 0x34(%rax),%esi 011e 11e: 40 80 fe 1f cmp $0x1f,%sil 0122 122: 76 02 jbe 126 <poke_int3_handler+0x126> 0124 124: 0f 0b ud2 0126 126: 40 0f b6 f6 movzbl %sil,%esi 012a 12a: 48 0f be b6 00 00 00 movsbq 0x0(%rsi),%rsi 0131 131: 00 012e 12e: R_X86_64_32S .rodata 0132 132: 48 01 f2 add %rsi,%rdx 0135 135: 3c e8 cmp $0xe8,%al 0137 137: 74 29 je 162 <poke_int3_handler+0x162> 0139 139: 77 08 ja 143 <poke_int3_handler+0x143> 013b 13b: 3c cc cmp $0xcc,%al 013d 13d: 75 e5 jne 124 <poke_int3_handler+0x124> 013f 13f: 31 c0 xor %eax,%eax 0141 141: eb 98 jmp db <poke_int3_handler+0xdb> 0143 143: 83 e0 fd and $0xfffffffd,%eax 0146 146: 3c e9 cmp $0xe9,%al 0148 148: 75 da jne 124 <poke_int3_handler+0x124> 014a 14a: 48 63 41 04 movslq 0x4(%rcx),%rax 014e 14e: 48 01 c2 add %rax,%rdx 0151 151: b8 01 00 00 00 mov $0x1,%eax 0156 156: 48 89 93 80 00 00 00 mov %rdx,0x80(%rbx) 015d 15d: e9 79 ff ff ff jmpq db <poke_int3_handler+0xdb> 0162 162: 48 63 41 04 movslq 0x4(%rcx),%rax 0166 166: 48 83 c7 04 add $0x4,%rdi 016a 16a: 48 01 c2 add %rax,%rdx 016d 16d: 48 8b 83 98 00 00 00 mov 0x98(%rbx),%rax 0174 174: 48 8d 48 f8 lea -0x8(%rax),%rcx 0178 178: 48 89 8b 98 00 00 00 mov %rcx,0x98(%rbx) 017f 17f: 48 89 78 f8 mov %rdi,-0x8(%rax) 0183 183: b8 01 00 00 00 mov $0x1,%eax 0188 188: 48 89 93 80 00 00 00 mov %rdx,0x80(%rbx) 018f 18f: e9 47 ff ff ff jmpq db <poke_int3_handler+0xdb> 0194 194: 4c 89 c0 mov %r8,%rax 0197 197: 48 85 c0 test %rax,%rax 019a 19a: 0f 85 49 ff ff ff jne e9 <poke_int3_handler+0xe9> 01a0 1a0: e9 36 ff ff ff jmpq db <poke_int3_handler+0xdb> 01a5 1a5: 48 83 e8 01 sub $0x1,%rax 01a9 1a9: 4c 8d 49 10 lea 0x10(%rcx),%r9 01ad 1ad: 48 d1 e8 shr %rax 01b0 1b0: eb e5 jmp 197 <poke_int3_handler+0x197> 01b2 1b2: e8 00 00 00 00 callq 1b7 <poke_int3_handler+0x1b7> 01b3 1b3: R_X86_64_PLT32 __stack_chk_fail-0x4 01b7 1b7: 4c 01 e0 add %r12,%rax 01ba 1ba: 0f 82 ab fe ff ff jb 6b <poke_int3_handler+0x6b> 01c0 1c0: 4c 89 e6 mov %r12,%rsi 01c3 1c3: 48 c7 c7 00 00 00 00 mov $0x0,%rdi 01c6 1c6: R_X86_64_32S .data+0x80 01ca 1ca: e8 00 00 00 00 callq 1cf <poke_int3_handler+0x1cf> 01cb 1cb: R_X86_64_PLT32 __ubsan_handle_type_mismatch_v1-0x4 01cf 1cf: e9 97 fe ff ff jmpq 6b <poke_int3_handler+0x6b> 01d4 1d4: 4c 01 e5 add %r12,%rbp 01d7 1d7: 0f 82 a4 fe ff ff jb 81 <poke_int3_handler+0x81> 01dd 1dd: 4c 89 e6 mov %r12,%rsi 01e0 1e0: 48 c7 c7 00 00 00 00 mov $0x0,%rdi 01e3 1e3: R_X86_64_32S .data+0x60 01e7 1e7: e8 00 00 00 00 callq 1ec <poke_int3_handler+0x1ec> 01e8 1e8: R_X86_64_PLT32 __ubsan_handle_type_mismatch_v1-0x4 01ec 1ec: e9 90 fe ff ff jmpq 81 <poke_int3_handler+0x81>
