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llvm-project/clang/test/CodeGen/cmse-clear-return.c

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[CMSE] Clear padding bits of struct/unions/fp16 passed by value When passing a value of a struct/union type from secure to non-secure state (that is returning from a CMSE entry function or passing an argument to CMSE-non-secure call), there is a potential sensitive information leak via the padding bits in the structure. It is not possible in the general case to ensure those bits are cleared by using Standard C/C++. This patch makes the compiler emit code to clear such padding bits. Since type information is lost in LLVM IR, the code generation is done by Clang. For each interesting record type, we build a bitmask, in which all the bits, corresponding to user declared members, are set. Values of record types are returned by coercing them to an integer. After the coercion, the coerced value is masked (with bitwise AND) and then returned by the function. In a similar manner, values of record types are passed as arguments by coercing them to an array of integers, and the coerced values themselves are masked. For union types, we effectively clear only bits, which aren't part of any member, since we don't know which is the currently active one. The compiler will issue a warning, whenever a union is passed to non-secure state. Values of half-precision floating-point types are passed in the least significant bits of a 32-bit register (GPR or FPR) with the most significant bits unspecified. Since this is also a potential leak of sensitive information, this patch also clears those unspecified bits. Differential Revision: https://reviews.llvm.org/D76369
2020-04-28 23:27:52 +08:00
// RUN: %clang_cc1 -triple thumbv8m.main -O0 -mcmse -S -emit-llvm %s -o - | \
// RUN: FileCheck %s --check-prefixes=CHECK,CHECK-LE,CHECK-LE-NOPT,CHECK-SOFT
// RUN: %clang_cc1 -triple thumbebv8m.main -O0 -mcmse -S -emit-llvm %s -o - | \
// RUN: FileCheck %s --check-prefixes=CHECK,CHECK-BE,CHECK-BE-NOPT,CHECK-SOFT
// RUN: %clang_cc1 -triple thumbv8m.main -O2 -mcmse -S -emit-llvm %s -o - | \
// RUN: FileCheck %s --check-prefixes=CHECK,CHECK-LE,CHECK-LE-OPT,CHECK-SOFT
// RUN: %clang_cc1 -triple thumbebv8m.main -O2 -mcmse -S -emit-llvm %s -o - | \
// RUN: FileCheck %s --check-prefixes=CHECK,CHECK-BE,CHECK-BE-OPT,CHECK-SOFT
// RUN: %clang_cc1 -triple thumbv8m.main -O0 -mcmse -S -emit-llvm %s -o - \
// RUN: -mfloat-abi hard | \
// RUN: FileCheck %s --check-prefixes=CHECK,CHECK-LE,CHECK-LE-NOPT,CHECK-HARD
// : Memory layout | Mask
// LE: .......1 ........ ........ ........ | 0x00000001/1
// BE: 1....... ........ ........ ........ | 0x80000000/-2147483648
typedef struct T0 {
int a : 1, : 31;
} T0;
T0 t0;
__attribute__((cmse_nonsecure_entry)) T0 f0() { return t0; }
// CHECK: define {{.*}} @f0()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 1
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, -2147483648
// CHECK: ret i32 %[[R]]
// LE: ......1. ........ ........ ........ 0x00000002/2
// BE: .1...... ........ ........ ........ 0x40000000/1073741824
typedef struct T1 {
int : 1, a : 1, : 30;
} T1;
T1 t1;
__attribute__((cmse_nonsecure_entry)) T1 f1() { return t1; }
// CHECK: define {{.*}} @f1()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 2
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, 1073741824
// CHECK: ret i32 %[[R]]
// LE: ........ .......1 ........ ........ 0x00000100/256
// BE: ........ 1....... ........ ........ 0x00800000/8388608
typedef struct T2 {
int : 8, a : 1, : 23;
} T2;
T2 t2;
__attribute__((cmse_nonsecure_entry)) T2 f2() { return t2; }
// CHECK: define {{.*}} @f2()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 256
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, 8388608
// CHECK: ret i32 %[[R]]
// LE: ........ .....1.. ........ ........ 0x00000400/1024
// BE: ........ ..1..... ........ ........ 0x00200000/2097152
typedef struct T3 {
int : 10, a : 1;
} T3;
T3 t3;
__attribute__((cmse_nonsecure_entry)) T3 f3() { return t3; }
// CHECK: define {{.*}} @f3()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 1024
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, 2097152
// CHECK: ret i32 %[[R]]
// LE: 11111111 ........ ........ ........ 0x000000ff/255
// BE: 11111111 ........ ........ ........ 0xff000000/-16777216
typedef struct T4 {
int a : 8, : 24;
} T4;
T4 t4;
__attribute__((cmse_nonsecure_entry)) T4 f4() { return t4; }
// CHECK: define {{.*}} @f4()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 255
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, -16777216
// CHECK: ret i32 %[[R]]
// LE: 1111111. .......1 ........ ........ 0x000001fe/510
// BE: .1111111 1....... ........ ........ 0x7f800000/2139095040
typedef struct T5 {
int : 1, a : 8, : 23;
} T5;
T5 t5;
__attribute__((cmse_nonsecure_entry)) T5 f5() { return t5; }
// CHECK: define {{.*}} @f5()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 510
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, 2139095040
// CHECK: ret i32 %[[R]]
// LE: 1111111. 11111111 ........ ........ 0x0000fffe/65534
// BE: .1111111 11111111 ........ ........ 0x7fff0000/2147418112
typedef struct T6 {
int : 1, a : 15, : 16;
} T6;
T6 t6;
__attribute__((cmse_nonsecure_entry)) T6 f6() { return t6; }
// CHECK: define {{.*}} @f6()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 65534
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, 2147418112
// CHECK: ret i32 %[[R]]
// LE: 1111111. 11111111 .......1 ........ 0x0001fffe/131070
// BE: .1111111 11111111 1....... ........ 0x7fff8000/2147450880
typedef struct T7 {
int : 1, a : 16, : 15;
} T7;
T7 t7;
__attribute__((cmse_nonsecure_entry)) T7 f7() { return t7; }
// CHECK: define {{.*}} @f7()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 131070
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, 2147450880
// CHECK: ret i32 %[[R]]
// LE: 11111111 111111.. 11111111 11111111 0xfffffcff/-769
// BE: 11111111 ..111111 11111111 11111111 0xff3fffff/-12582913
typedef struct T8 {
struct T80 {
char a;
char : 2, b : 6;
} a;
short b;
} T8;
T8 t8;
__attribute__((cmse_nonsecure_entry)) T8 f8() { return t8; }
// CHECK: define {{.*}} @f8()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, -769
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, -12582913
// CHECK: ret i32 %[[R]]
// LE: ......11 ..111111 ...11111 ........ 0x001f3f03/2047747
// BE: 11...... 111111.. 11111... ........ 0xc0fcf800/-1057163264
typedef struct T9 {
struct T90 {
char a : 2;
char : 0;
short b : 6;
} a;
int b : 5;
} T9;
T9 t9;
__attribute__((cmse_nonsecure_entry)) T9 f9() { return t9; }
// CHECK: define {{.*}} @f9()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 2047747
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, -1057163264
// CHECK: ret i32 %[[R]]
T9 f91() { return t9; }
// CHECK: define {{.*}} @f91()
// CHECK: %[[R:.*]] = load i32
// CHECK: ret i32 %[[R]]
// LE: 11111111 ........ 11111111 11111111 0xffff00ff/-65281
// BE: 11111111 ........ 11111111 11111111 0xff00ffff/16711681
typedef struct T10 {
char a;
short b;
} T10;
T10 t10;
__attribute__((cmse_nonsecure_entry)) T10 f10() { return t10; }
// CHECK: define {{.*}} @f10()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, -65281
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, -16711681
// CHECK: ret i32 %[[R]]
// LE: 11111111 11111111 11111111 ........ 0x00ffffff/16777215
// BE: 11111111 11111111 11111111 ........ 0xffffff00/-256
typedef struct T11 {
short a;
char b;
} T11;
T11 t11;
__attribute__((cmse_nonsecure_entry)) T11 f11() { return t11; }
// CHECK: define {{.*}} @f11()
// CHECK-LE: %[[R:.*]] = and i32 %{{.*}}, 16777215
// CHECK-BE: %[[R:.*]] = and i32 %{{.*}}, -256
// CHECK: ret i32 %[[R]]
// LE: 11111111 11111111 11111111 ........ 0x00ffffff/16777215
// BE: 11111111 11111111 11111111 ........ 0xffffff00/-256
typedef struct T12 {
char a[3];
} T12;
T12 t12;
__attribute__((cmse_nonsecure_entry)) T12 f12() { return t12; }
// CHECK: define {{.*}} @f12()
// CHECK-LE-OPT: %[[V0:.*]] = load i24, i24* bitcast (%struct.T12* @t12
// CHECK-LE-OPT: %[[R:.*]] = zext i24 %[[V0]] to i32
// CHECK-LE-NOPT: %[[R:.*]] = and i32 %{{.*}}, 16777215
// CHECK-BE-OPT: %[[V0:.*]] = load i24, i24* bitcast (%struct.T12* @t12
// CHECK-BE-OPT: %[[V1:.*]] = zext i24 %[[V0]] to i32
// CHECK-BE-OPT: %[[R:.*]] = shl nuw i32 %[[V1]], 8
// CHECK: ret i32 %[[R]]
// LE: 11111111 11111111 11111111 ........ 0x00ffffff/16777215
// BE: 11111111 11111111 11111111 ........ 0xffffff00/-256
typedef struct __attribute__((packed)) T13 {
char a;
short b;
} T13;
T13 t13;
__attribute__((cmse_nonsecure_entry)) T13 f13() { return t13; }
// CHECK: define {{.*}} @f13()
// CHECK-LE-OPT: %[[V0:.*]] = load i24, i24* bitcast (%struct.T13* @t13
// CHECK-LE-OPT: %[[R:.*]] = zext i24 %[[V0]] to i32
// CHECK-LE-NOPT: %[[R:.*]] = and i32 %{{.*}}, 16777215
// CHECK-BE-OPT: %[[V0:.*]] = load i24, i24* bitcast (%struct.T13* @t13
// CHECK-BE-OPT: %[[V1:.*]] = zext i24 %[[V0]] to i32
// CHECK-BE-OPT: %[[R:.*]] = shl nuw i32 %[[V1]], 8
// CHECK: ret i32 %[[R]]
typedef struct __attribute__((packed)) T14 {
short a;
short b;
} T14;
T14 t14;
__attribute__((cmse_nonsecure_entry)) T14 f14() { return t14; }
// CHECK: define {{.*}} @f14()
// CHECK: %[[R:.*]] = load
// CHECK: ret i32 %[[R]]
// LE: 1111..11 1111..11 11111111 11111111 0xfffff3f3/-3085
// BE: 11..1111 11..1111 11111111 11111111 0xcfcfffff/-808452097
typedef struct T17 {
struct T170 {
char a : 2;
char : 2, b : 4;
} a[2];
char b[2];
char c[];
} T17;
T17 t17;
__attribute__((cmse_nonsecure_entry)) T17 f17() { return t17; }
// CHECK: define {{.*}} @f17()
// CHECK-LE: %[[R:.*]] = and i32 {{.*}}, -3085
// CHECK-BE: %[[R:.*]] = and i32 {{.*}}, -808452097
// CHECK: ret i32 %[[R]]
typedef struct T21 {
float a;
} T21;
T21 t21;
__attribute__((cmse_nonsecure_entry)) T21 f21() { return t21; }
// CHECK: define {{.*}} @f21()
// CHECK-SOFT: ret i32
// CHECK-HARD: ret %struct.T21
__attribute__((cmse_nonsecure_entry)) float f22() { return 1.0f; }
// CHECK: define {{.*}} @f22()
// CHECK: ret float