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linux/arch/powerpc/kernel/vdso32/gettimeofday.S
Tony Breeds 74609f4536 [POWERPC] Fix VDSO gettimeofday() when called with NULL struct timeval 
Consider the prototype for gettimeofday():
	int gettimofday(struct timeval *tv, struct timezone *tz);

Although it is valid to call with /either/ tv or tz being NULL, and
the C version of sys_gettimeofday() supports this, the current version
of gettimeofday() in the VDSO will SEGV if called with a NULL tv.

This adds a check for tv being NULL so that it doesn't SEGV.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-06-26 14:41:19 +10:00

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/*
* Userland implementation of gettimeofday() for 32 bits processes in a
* ppc64 kernel for use in the vDSO
*
* Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org,
* IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/vdso.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
.text
/*
* Exact prototype of gettimeofday
*
* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
*
*/
V_FUNCTION_BEGIN(__kernel_gettimeofday)
.cfi_startproc
mflr r12
.cfi_register lr,r12
mr r10,r3 /* r10 saves tv */
mr r11,r4 /* r11 saves tz */
bl __get_datapage@local /* get data page */
mr r9, r3 /* datapage ptr in r9 */
cmplwi r10,0 /* check if tv is NULL */
beq 3f
bl __do_get_xsec@local /* get xsec from tb & kernel */
bne- 2f /* out of line -> do syscall */
/* seconds are xsec >> 20 */
rlwinm r5,r4,12,20,31
rlwimi r5,r3,12,0,19
stw r5,TVAL32_TV_SEC(r10)
/* get remaining xsec and convert to usec. we scale
* up remaining xsec by 12 bits and get the top 32 bits
* of the multiplication
*/
rlwinm r5,r4,12,0,19
lis r6,1000000@h
ori r6,r6,1000000@l
mulhwu r5,r5,r6
stw r5,TVAL32_TV_USEC(r10)
3: cmplwi r11,0 /* check if tz is NULL */
beq 1f
lwz r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
lwz r5,CFG_TZ_DSTTIME(r9)
stw r4,TZONE_TZ_MINWEST(r11)
stw r5,TZONE_TZ_DSTTIME(r11)
1: mtlr r12
crclr cr0*4+so
li r3,0
blr
2:
mtlr r12
mr r3,r10
mr r4,r11
li r0,__NR_gettimeofday
sc
blr
.cfi_endproc
V_FUNCTION_END(__kernel_gettimeofday)
/*
* Exact prototype of clock_gettime()
*
* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
*
*/
V_FUNCTION_BEGIN(__kernel_clock_gettime)
.cfi_startproc
/* Check for supported clock IDs */
cmpli cr0,r3,CLOCK_REALTIME
cmpli cr1,r3,CLOCK_MONOTONIC
cror cr0*4+eq,cr0*4+eq,cr1*4+eq
bne cr0,99f
mflr r12 /* r12 saves lr */
.cfi_register lr,r12
mr r10,r3 /* r10 saves id */
mr r11,r4 /* r11 saves tp */
bl __get_datapage@local /* get data page */
mr r9,r3 /* datapage ptr in r9 */
beq cr1,50f /* if monotonic -> jump there */
/*
* CLOCK_REALTIME
*/
bl __do_get_xsec@local /* get xsec from tb & kernel */
bne- 98f /* out of line -> do syscall */
/* seconds are xsec >> 20 */
rlwinm r5,r4,12,20,31
rlwimi r5,r3,12,0,19
stw r5,TSPC32_TV_SEC(r11)
/* get remaining xsec and convert to nsec. we scale
* up remaining xsec by 12 bits and get the top 32 bits
* of the multiplication, then we multiply by 1000
*/
rlwinm r5,r4,12,0,19
lis r6,1000000@h
ori r6,r6,1000000@l
mulhwu r5,r5,r6
mulli r5,r5,1000
stw r5,TSPC32_TV_NSEC(r11)
mtlr r12
crclr cr0*4+so
li r3,0
blr
/*
* CLOCK_MONOTONIC
*/
50: bl __do_get_xsec@local /* get xsec from tb & kernel */
bne- 98f /* out of line -> do syscall */
/* seconds are xsec >> 20 */
rlwinm r6,r4,12,20,31
rlwimi r6,r3,12,0,19
/* get remaining xsec and convert to nsec. we scale
* up remaining xsec by 12 bits and get the top 32 bits
* of the multiplication, then we multiply by 1000
*/
rlwinm r7,r4,12,0,19
lis r5,1000000@h
ori r5,r5,1000000@l
mulhwu r7,r7,r5
mulli r7,r7,1000
/* now we must fixup using wall to monotonic. We need to snapshot
* that value and do the counter trick again. Fortunately, we still
* have the counter value in r8 that was returned by __do_get_xsec.
* At this point, r6,r7 contain our sec/nsec values, r3,r4 and r5
* can be used
*/
lwz r3,WTOM_CLOCK_SEC(r9)
lwz r4,WTOM_CLOCK_NSEC(r9)
/* We now have our result in r3,r4. We create a fake dependency
* on that result and re-check the counter
*/
or r5,r4,r3
xor r0,r5,r5
add r9,r9,r0
#ifdef CONFIG_PPC64
lwz r0,(CFG_TB_UPDATE_COUNT+4)(r9)
#else
lwz r0,(CFG_TB_UPDATE_COUNT)(r9)
#endif
cmpl cr0,r8,r0 /* check if updated */
bne- 50b
/* Calculate and store result. Note that this mimmics the C code,
* which may cause funny results if nsec goes negative... is that
* possible at all ?
*/
add r3,r3,r6
add r4,r4,r7
lis r5,NSEC_PER_SEC@h
ori r5,r5,NSEC_PER_SEC@l
cmpl cr0,r4,r5
cmpli cr1,r4,0
blt 1f
subf r4,r5,r4
addi r3,r3,1
1: bge cr1,1f
addi r3,r3,-1
add r4,r4,r5
1: stw r3,TSPC32_TV_SEC(r11)
stw r4,TSPC32_TV_NSEC(r11)
mtlr r12
crclr cr0*4+so
li r3,0
blr
/*
* syscall fallback
*/
98:
mtlr r12
mr r3,r10
mr r4,r11
99:
li r0,__NR_clock_gettime
sc
blr
.cfi_endproc
V_FUNCTION_END(__kernel_clock_gettime)
/*
* Exact prototype of clock_getres()
*
* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
*
*/
V_FUNCTION_BEGIN(__kernel_clock_getres)
.cfi_startproc
/* Check for supported clock IDs */
cmpwi cr0,r3,CLOCK_REALTIME
cmpwi cr1,r3,CLOCK_MONOTONIC
cror cr0*4+eq,cr0*4+eq,cr1*4+eq
bne cr0,99f
li r3,0
cmpli cr0,r4,0
crclr cr0*4+so
beqlr
lis r5,CLOCK_REALTIME_RES@h
ori r5,r5,CLOCK_REALTIME_RES@l
stw r3,TSPC32_TV_SEC(r4)
stw r5,TSPC32_TV_NSEC(r4)
blr
/*
* syscall fallback
*/
99:
li r0,__NR_clock_getres
sc
blr
.cfi_endproc
V_FUNCTION_END(__kernel_clock_getres)
/*
* This is the core of gettimeofday() & friends, it returns the xsec
* value in r3 & r4 and expects the datapage ptr (non clobbered)
* in r9. clobbers r0,r4,r5,r6,r7,r8.
* When returning, r8 contains the counter value that can be reused
* by the monotonic clock implementation
*/
__do_get_xsec:
.cfi_startproc
/* Check for update count & load values. We use the low
* order 32 bits of the update count
*/
#ifdef CONFIG_PPC64
1: lwz r8,(CFG_TB_UPDATE_COUNT+4)(r9)
#else
1: lwz r8,(CFG_TB_UPDATE_COUNT)(r9)
#endif
andi. r0,r8,1 /* pending update ? loop */
bne- 1b
xor r0,r8,r8 /* create dependency */
add r9,r9,r0
/* Load orig stamp (offset to TB) */
lwz r5,CFG_TB_ORIG_STAMP(r9)
lwz r6,(CFG_TB_ORIG_STAMP+4)(r9)
/* Get a stable TB value */
2: mftbu r3
mftbl r4
mftbu r0
cmpl cr0,r3,r0
bne- 2b
/* Substract tb orig stamp. If the high part is non-zero, we jump to
* the slow path which call the syscall.
* If it's ok, then we have our 32 bits tb_ticks value in r7
*/
subfc r7,r6,r4
subfe. r0,r5,r3
bne- 3f
/* Load scale factor & do multiplication */
lwz r5,CFG_TB_TO_XS(r9) /* load values */
lwz r6,(CFG_TB_TO_XS+4)(r9)
mulhwu r4,r7,r5
mulhwu r6,r7,r6
mullw r0,r7,r5
addc r6,r6,r0
/* At this point, we have the scaled xsec value in r4 + XER:CA
* we load & add the stamp since epoch
*/
lwz r5,CFG_STAMP_XSEC(r9)
lwz r6,(CFG_STAMP_XSEC+4)(r9)
adde r4,r4,r6
addze r3,r5
/* We now have our result in r3,r4. We create a fake dependency
* on that result and re-check the counter
*/
or r6,r4,r3
xor r0,r6,r6
add r9,r9,r0
#ifdef CONFIG_PPC64
lwz r0,(CFG_TB_UPDATE_COUNT+4)(r9)
#else
lwz r0,(CFG_TB_UPDATE_COUNT)(r9)
#endif
cmpl cr0,r8,r0 /* check if updated */
bne- 1b
/* Warning ! The caller expects CR:EQ to be set to indicate a
* successful calculation (so it won't fallback to the syscall
* method). We have overriden that CR bit in the counter check,
* but fortunately, the loop exit condition _is_ CR:EQ set, so
* we can exit safely here. If you change this code, be careful
* of that side effect.
*/
3: blr
.cfi_endproc
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