1#include "sanitizer_common/sanitizer_asm.h"
2
3// The content of this file is RISCV64-only:
4#if defined(__riscv) && (__riscv_xlen == 64)
5
6// The responsibility of the HWASan entry point in compiler-rt is to primarily
7// readjust the stack from the callee and save the current register values to
8// the stack.
9// This entry point function should be called from a __hwasan_check_* symbol.
10// These are generated during a lowering pass in the backend, and are found in
11// RISCVAsmPrinter::EmitHwasanMemaccessSymbols(). Please look there for
12// further information.
13// The __hwasan_check_* caller of this function should have expanded the stack
14// and saved the previous values of x10(arg0), x11(arg1), x1(ra), and x8(fp).
15// This function will "consume" these saved values and treats it as part of its
16// own stack frame. In this sense, the __hwasan_check_* callee and this function
17// "share" a stack frame. This allows us to omit having unwinding information
18// (.cfi_*) present in every __hwasan_check_* function, therefore reducing binary size.
19// This is particularly important as hwasan_check_* instances are duplicated in every
20// translation unit where HWASan is enabled.
21// This function calls HwasanTagMismatch to step back into the C++ code that
22// completes the stack unwinding and error printing. This function is is not
23// permitted to return.
24
25
26// | ... |
27// | ... |
28// | Previous stack frames... |
29// +=================================+
30// | ... |
31// | |
32// | Stack frame space for x12 - x31.|
33// | |
34// | ... |
35// +---------------------------------+ <-- [SP + 96]
36// | Saved x11(arg1), as |
37// | __hwasan_check_* clobbers it. |
38// +---------------------------------+ <-- [SP + 88]
39// | Saved x10(arg0), as |
40// | __hwasan_check_* clobbers it. |
41// +---------------------------------+ <-- [SP + 80]
42// | |
43// | Stack frame space for x9. |
44// +---------------------------------+ <-- [SP + 72]
45// | |
46// | Saved x8(fp), as |
47// | __hwasan_check_* clobbers it. |
48// +---------------------------------+ <-- [SP + 64]
49// | ... |
50// | |
51// | Stack frame space for x2 - x7. |
52// | |
53// | ... |
54// +---------------------------------+ <-- [SP + 16]
55// | Return address (x1) for caller |
56// | of __hwasan_check_*. |
57// +---------------------------------+ <-- [SP + 8]
58// | Reserved place for x0, possibly |
59// | junk, since we don't save it. |
60// +---------------------------------+ <-- [x2 / SP]
61
62// This function takes two arguments:
63// * x10/a0: The data address.
64// * x11/a1: The encoded access info for the failing access.
65
66.section .text
67.file "hwasan_tag_mismatch_riscv64.S"
68
69.global __hwasan_tag_mismatch_v2
70ASM_TYPE_FUNCTION(__hwasan_tag_mismatch_v2)
71__hwasan_tag_mismatch_v2:
72 CFI_STARTPROC
73
74 // Set the CFA to be the return address for caller of __hwasan_check_*. Note
75 // that we do not emit CFI predicates to describe the contents of this stack
76 // frame, as this proxy entry point should never be debugged. The contents
77 // are static and are handled by the unwinder after calling
78 // __hwasan_tag_mismatch. The frame pointer is already correctly setup
79 // by __hwasan_check_*.
80 addi fp, sp, 256
81 CFI_DEF_CFA(fp, 0)
82 CFI_OFFSET(ra, -248)
83 CFI_OFFSET(fp, -192)
84
85 // Save the rest of the registers into the preallocated space left by
86 // __hwasan_check.
87 sd x31, 248(sp)
88 sd x30, 240(sp)
89 sd x29, 232(sp)
90 sd x28, 224(sp)
91 sd x27, 216(sp)
92 sd x26, 208(sp)
93 sd x25, 200(sp)
94 sd x24, 192(sp)
95 sd x23, 184(sp)
96 sd x22, 176(sp)
97 sd x21, 168(sp)
98 sd x20, 160(sp)
99 sd x19, 152(sp)
100 sd x18, 144(sp)
101 sd x17, 136(sp)
102 sd x16, 128(sp)
103 sd x15, 120(sp)
104 sd x14, 112(sp)
105 sd x13, 104(sp)
106 sd x12, 96(sp)
107 // sd x11, 88(sp) ; already saved
108 // sd x10, 80(sp) ; already saved
109 sd x9, 72(sp)
110 // sd x8, 64(sp) ; already saved
111 sd x7, 56(sp)
112 sd x6, 48(sp)
113 sd x5, 40(sp)
114 sd x4, 32(sp)
115 sd x3, 24(sp)
116 sd x2, 16(sp)
117 // sd x1, 8(sp) ; already saved
118 // sd x0, 0(sp) ; don't store zero register
119
120 // Pass the address of the frame to __hwasan_tag_mismatch4, so that it can
121 // extract the saved registers from this frame without having to worry about
122 // finding this frame.
123 mv x12, sp
124
125 call __hwasan_tag_mismatch4
126 CFI_ENDPROC
127ASM_SIZE(__hwasan_tag_mismatch_v2)
128
129#endif // defined(__riscv) && (__riscv_xlen == 64)
130
131// We do not need executable stack.
132NO_EXEC_STACK_DIRECTIVE
133

source code of compiler-rt/lib/hwasan/hwasan_tag_mismatch_riscv64.S