/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Userland implementation of getrandom() for processes
* for use in the vDSO
*
* Copyright (C) 2024 Christophe Leroy <[email protected]>, CS GROUP France
*/
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
/*
* The macro sets two stack frames, one for the caller and one for the callee
* because there are no requirement for the caller to set a stack frame when
* calling VDSO so it may have omitted to set one, especially on PPC64
*/
.macro cvdso_call funct
.cfi_startproc
PPC_STLU r1, -PPC_MIN_STKFRM(r1)
.cfi_adjust_cfa_offset PPC_MIN_STKFRM
mflr r0
PPC_STLU r1, -PPC_MIN_STKFRM(r1)
.cfi_adjust_cfa_offset PPC_MIN_STKFRM
PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
.cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
#ifdef __powerpc64__
PPC_STL r2, PPC_MIN_STKFRM + STK_GOT(r1)
.cfi_rel_offset r2, PPC_MIN_STKFRM + STK_GOT
#endif
get_realdatapage r8, r11
addi r8, r8, VDSO_RNG_DATA_OFFSET
bl CFUNC(DOTSYM(\funct))
PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
#ifdef __powerpc64__
PPC_LL r2, PPC_MIN_STKFRM + STK_GOT(r1)
.cfi_restore r2
#endif
cmpwi r3, 0
mtlr r0
addi r1, r1, 2 * PPC_MIN_STKFRM
.cfi_restore lr
.cfi_def_cfa_offset 0
crclr so
bgelr+
crset so
neg r3, r3
blr
.cfi_endproc
.endm
.text
V_FUNCTION_BEGIN(__kernel_getrandom)
cvdso_call __c_kernel_getrandom
V_FUNCTION_END(__kernel_getrandom)
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