| 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */
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| 2 | /*
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| 3 | * Userland implementation of getrandom() for processes
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| 4 | * for use in the vDSO
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| 5 | *
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| 6 | * Copyright (C) 2024 Christophe Leroy <christophe.leroy@csgroup.eu>, CS GROUP France
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| 7 | */
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| 8 | |
| 9 | |
| 10 | |
| 11 | |
| 12 | |
| 13 | |
| 14 |
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| 15 | /*
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| 16 | * The macro sets two stack frames, one for the caller and one for the callee
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| 17 | * because there are no requirement for the caller to set a stack frame when
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| 18 | * calling VDSO so it may have omitted to set one, especially on PPC64
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| 19 | */
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| 20 |
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| 21 | .macro cvdso_call funct
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| 22 | .cfi_startproc
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| 23 | PPC_STLU r1, -PPC_MIN_STKFRM(r1)
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| 24 | .cfi_adjust_cfa_offset PPC_MIN_STKFRM
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| 25 | mflr r0
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| 26 | PPC_STLU r1, -PPC_MIN_STKFRM(r1)
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| 27 | .cfi_adjust_cfa_offset PPC_MIN_STKFRM
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| 28 | PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
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| 29 | .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
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| 30 | |
| 31 | PPC_STL r2, PPC_MIN_STKFRM + STK_GOT(r1)
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| 32 | .cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
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| 33 | |
| 34 | bl CFUNC(DOTSYM(\funct))
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| 35 | PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
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| 36 | |
| 37 | PPC_LL r2, PPC_MIN_STKFRM + STK_GOT(r1)
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| 38 | .cfi_restore r2
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| 39 | |
| 40 | cmpwi r3, 0
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| 41 | mtlr r0
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| 42 | addi r1, r1, 2 * PPC_MIN_STKFRM
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| 43 | .cfi_restore lr
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| 44 | .cfi_def_cfa_offset 0
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| 45 | crclr so
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| 46 | bgelr+
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| 47 | crset so
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| 48 | neg r3, r3
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| 49 | blr
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| 50 | .cfi_endproc
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| 51 | .endm
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| 52 |
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| 53 | .text
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| 54 | V_FUNCTION_BEGIN(__kernel_getrandom)
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| 55 | cvdso_call __c_kernel_getrandom
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| 56 | V_FUNCTION_END(__kernel_getrandom)
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