| 1 | //===-- Implementation of setjmp for AArch64 ------------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "src/__support/common.h" |
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| 10 | #include "src/__support/macros/config.h" |
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| 11 | #include "src/setjmp/setjmp_impl.h" |
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| 12 | |
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| 13 | namespace LIBC_NAMESPACE_DECL { |
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| 14 | |
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| 15 | [[gnu::naked]] LLVM_LIBC_FUNCTION(int, setjmp, ([[maybe_unused]] jmp_buf buf)) { |
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| 16 | // If BTI branch protection is in use, the compiler will automatically insert |
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| 17 | // a BTI here, so we don't need to make any extra effort to do so. |
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| 18 | |
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| 19 | asm( |
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| 20 | #if __ARM_FEATURE_PAC_DEFAULT & 1 |
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| 21 | // Sign the return address using the PAC A key. |
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| 22 | R"( |
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| 23 | paciasp |
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| 24 | )" |
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| 25 | #elif __ARM_FEATURE_PAC_DEFAULT & 2 |
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| 26 | // Sign the return address using the PAC B key. |
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| 27 | R"( |
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| 28 | pacibsp |
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| 29 | )" |
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| 30 | #endif |
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| 31 | |
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| 32 | // Store all the callee-saved GPRs, including fp (x29) and also lr (x30). |
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| 33 | // Of course lr isn't normally callee-saved (the call instruction itself |
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| 34 | // can't help clobbering it), but we certainly need to save it for this |
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| 35 | // purpose. |
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| 36 | R"( |
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| 37 | stp x19, x20, [x0, #0*16] |
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| 38 | stp x21, x22, [x0, #1*16] |
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| 39 | stp x23, x24, [x0, #2*16] |
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| 40 | stp x25, x26, [x0, #3*16] |
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| 41 | stp x27, x28, [x0, #4*16] |
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| 42 | stp x29, x30, [x0, #5*16] |
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| 43 | )" |
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| 44 | |
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| 45 | #if LIBC_COPT_SETJMP_AARCH64_RESTORE_PLATFORM_REGISTER |
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| 46 | // Store the stack pointer, and the platform register x18. |
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| 47 | R"( |
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| 48 | add x1, sp, #0 |
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| 49 | stp x1, x18, [x0, #6*16] |
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| 50 | )" |
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| 51 | #else |
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| 52 | // Store just the stack pointer. |
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| 53 | R"( |
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| 54 | add x1, sp, #0 |
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| 55 | str x1, [x0, #6*16] |
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| 56 | )" |
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| 57 | #endif |
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| 58 | |
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| 59 | #if __ARM_FP |
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| 60 | // Store the callee-saved FP registers. AAPCS64 only requires the low 64 |
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| 61 | // bits of v8-v15 to be preserved, i.e. each of d8,...,d15. |
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| 62 | R"( |
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| 63 | stp d8, d9, [x0, #7*16] |
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| 64 | stp d10, d11, [x0, #8*16] |
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| 65 | stp d12, d13, [x0, #9*16] |
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| 66 | stp d14, d15, [x0, #10*16] |
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| 67 | )" |
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| 68 | #endif |
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| 69 | |
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| 70 | // Set up return value of zero. |
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| 71 | R"( |
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| 72 | mov x0, #0 |
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| 73 | )" |
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| 74 | |
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| 75 | #if (__ARM_FEATURE_PAC_DEFAULT & 7) == 5 |
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| 76 | // Authenticate the return address using the PAC A key, since the |
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| 77 | // compilation options ask for PAC protection even on leaf functions. |
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| 78 | R"( |
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| 79 | autiasp |
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| 80 | )" |
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| 81 | #elif (__ARM_FEATURE_PAC_DEFAULT & 7) == 6 |
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| 82 | // Same, but using the PAC B key. |
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| 83 | R"( |
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| 84 | autibsp |
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| 85 | )" |
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| 86 | #endif |
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| 87 | |
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| 88 | R"( |
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| 89 | ret |
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| 90 | )" ); |
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| 91 | } |
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| 92 | |
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| 93 | } // namespace LIBC_NAMESPACE_DECL |
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| 94 | |
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