forked from luck/tmp_suning_uos_patched
bdceb6a016
The ppc vDSO would not properly clear the return value for some calls, which will be a problem when interfacing those calls with glibc. This should be fixed before 2.6.12 is released (as it is the first kernel with the ppc vDSO) so that we don't have to play with symbol versioning and ugly workarounds. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
141 lines
3.5 KiB
ArmAsm
141 lines
3.5 KiB
ArmAsm
/*
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* Userland implementation of gettimeofday() for 32 bits processes in a
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* ppc64 kernel for use in the vDSO
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*
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* Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org), IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/config.h>
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#include <asm/processor.h>
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#include <asm/ppc_asm.h>
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#include <asm/vdso.h>
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#include <asm/offsets.h>
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#include <asm/unistd.h>
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.text
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/*
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* Exact prototype of gettimeofday
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*
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* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
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*
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*/
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V_FUNCTION_BEGIN(__kernel_gettimeofday)
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.cfi_startproc
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mflr r12
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.cfi_register lr,r12
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mr r10,r3 /* r10 saves tv */
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mr r11,r4 /* r11 saves tz */
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bl __get_datapage@local /* get data page */
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mr r9, r3 /* datapage ptr in r9 */
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bl __do_get_xsec@local /* get xsec from tb & kernel */
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bne- 2f /* out of line -> do syscall */
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/* seconds are xsec >> 20 */
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rlwinm r5,r4,12,20,31
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rlwimi r5,r3,12,0,19
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stw r5,TVAL32_TV_SEC(r10)
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/* get remaining xsec and convert to usec. we scale
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* up remaining xsec by 12 bits and get the top 32 bits
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* of the multiplication
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*/
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rlwinm r5,r4,12,0,19
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lis r6,1000000@h
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ori r6,r6,1000000@l
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mulhwu r5,r5,r6
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stw r5,TVAL32_TV_USEC(r10)
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cmpli cr0,r11,0 /* check if tz is NULL */
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beq 1f
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lwz r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
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lwz r5,CFG_TZ_DSTTIME(r9)
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stw r4,TZONE_TZ_MINWEST(r11)
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stw r5,TZONE_TZ_DSTTIME(r11)
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1: mtlr r12
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li r3,0
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blr
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2: mr r3,r10
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mr r4,r11
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li r0,__NR_gettimeofday
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sc
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b 1b
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.cfi_endproc
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V_FUNCTION_END(__kernel_gettimeofday)
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/*
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* This is the core of gettimeofday(), it returns the xsec
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* value in r3 & r4 and expects the datapage ptr (non clobbered)
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* in r9. clobbers r0,r4,r5,r6,r7,r8
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*/
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__do_get_xsec:
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.cfi_startproc
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/* Check for update count & load values. We use the low
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* order 32 bits of the update count
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*/
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1: lwz r8,(CFG_TB_UPDATE_COUNT+4)(r9)
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andi. r0,r8,1 /* pending update ? loop */
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bne- 1b
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xor r0,r8,r8 /* create dependency */
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add r9,r9,r0
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/* Load orig stamp (offset to TB) */
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lwz r5,CFG_TB_ORIG_STAMP(r9)
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lwz r6,(CFG_TB_ORIG_STAMP+4)(r9)
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/* Get a stable TB value */
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2: mftbu r3
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mftbl r4
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mftbu r0
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cmpl cr0,r3,r0
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bne- 2b
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/* Substract tb orig stamp. If the high part is non-zero, we jump to the
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* slow path which call the syscall. If it's ok, then we have our 32 bits
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* tb_ticks value in r7
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*/
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subfc r7,r6,r4
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subfe. r0,r5,r3
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bne- 3f
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/* Load scale factor & do multiplication */
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lwz r5,CFG_TB_TO_XS(r9) /* load values */
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lwz r6,(CFG_TB_TO_XS+4)(r9)
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mulhwu r4,r7,r5
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mulhwu r6,r7,r6
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mullw r6,r7,r5
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addc r6,r6,r0
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/* At this point, we have the scaled xsec value in r4 + XER:CA
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* we load & add the stamp since epoch
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*/
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lwz r5,CFG_STAMP_XSEC(r9)
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lwz r6,(CFG_STAMP_XSEC+4)(r9)
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adde r4,r4,r6
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addze r3,r5
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/* We now have our result in r3,r4. We create a fake dependency
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* on that result and re-check the counter
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*/
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xor r0,r4,r4
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add r9,r9,r0
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lwz r0,(CFG_TB_UPDATE_COUNT+4)(r9)
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cmpl cr0,r8,r0 /* check if updated */
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bne- 1b
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/* Warning ! The caller expects CR:EQ to be set to indicate a
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* successful calculation (so it won't fallback to the syscall
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* method). We have overriden that CR bit in the counter check,
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* but fortunately, the loop exit condition _is_ CR:EQ set, so
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* we can exit safely here. If you change this code, be careful
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* of that side effect.
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*/
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3: blr
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.cfi_endproc
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