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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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9b2efe035e
The kernel provided vdso functions do not get a stack frame from the
calling function and therefore may not change the stack contents, unless
they allocate space on their own.
This problem was exposed with 070b7be633 "s390/vdso: replace stck with
stcke" which writes 16 bytes instead of 8 bytes into the stack frame. These
additional 8 bytes however were indeed used by the caller (glibc) to save
data and therefore this data was corrupted by the vdso code.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
60 lines
1.6 KiB
ArmAsm
60 lines
1.6 KiB
ArmAsm
/*
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* Userland implementation of gettimeofday() for 64 bits processes in a
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* s390 kernel for use in the vDSO
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*
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*/
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#include <asm/vdso.h>
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#include <asm/asm-offsets.h>
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#include <asm/unistd.h>
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.text
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.align 4
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.globl __kernel_gettimeofday
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.type __kernel_gettimeofday,@function
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__kernel_gettimeofday:
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.cfi_startproc
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aghi %r15,-16
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larl %r5,_vdso_data
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0: ltgr %r3,%r3 /* check if tz is NULL */
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je 1f
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mvc 0(8,%r3),__VDSO_TIMEZONE(%r5)
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1: ltgr %r2,%r2 /* check if tv is NULL */
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je 4f
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lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
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tmll %r4,0x0001 /* pending update ? loop */
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jnz 0b
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stcke 0(%r15) /* Store TOD clock */
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lg %r1,1(%r15)
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sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
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msgf %r1,__VDSO_TK_MULT(%r5) /* * tk->mult */
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alg %r1,__VDSO_XTIME_NSEC(%r5) /* + tk->xtime_nsec */
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lg %r0,__VDSO_XTIME_SEC(%r5) /* tk->xtime_sec */
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clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */
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jne 0b
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lgf %r5,__VDSO_TK_SHIFT(%r5) /* Timekeeper shift */
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srlg %r1,%r1,0(%r5) /* >> tk->shift */
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larl %r5,5f
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2: clg %r1,0(%r5)
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jl 3f
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slg %r1,0(%r5)
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aghi %r0,1
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j 2b
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3: stg %r0,0(%r2) /* store tv->tv_sec */
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slgr %r0,%r0 /* tv_nsec -> tv_usec */
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ml %r0,8(%r5)
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srlg %r0,%r0,6
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stg %r0,8(%r2) /* store tv->tv_usec */
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4: lghi %r2,0
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aghi %r15,16
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br %r14
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5: .quad 1000000000
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.long 274877907
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.cfi_endproc
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.size __kernel_gettimeofday,.-__kernel_gettimeofday
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