7bceec4e58
Revise and add CFI CFA and register rule annotations to the vDSO functions for proper stack unwinding and debugging. Because glibc might call the vDSO in special ways, the vDSO code does not rely on a stack frame created by the caller. The TOD clock value can be therefore not stored in the pre-allocated stack area and additional stack space is required. To correctly annotate these situations with CFI, the .cfi_val_offset directive is required to create relative offsets on the value of the stack register %r15. Because the .cfi_val_offset directive is available with recent GNU assembler versions only, additional checks are necessary. Note that if the vDSO is assembled with an older assembler version, stack unwinding and debugging from within the vDSO code might not be possible. Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
71 lines
1.9 KiB
ArmAsm
71 lines
1.9 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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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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#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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#include <asm/dwarf.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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CFI_ADJUST_CFA_OFFSET 16
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CFI_VAL_OFFSET 15, -160
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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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lg %r0,__VDSO_TS_END(%r5) /* TOD steering end time */
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slgr %r0,%r1 /* now - ts_steering_end */
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ltgr %r0,%r0 /* past end of steering ? */
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jm 6f
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srlg %r0,%r0,15 /* 1 per 2^16 */
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tm __VDSO_TS_DIR+3(%r5),0x01 /* steering direction? */
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jz 7f
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lcgr %r0,%r0 /* negative TOD offset */
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7: algr %r1,%r0 /* add steering offset */
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6: 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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CFI_ADJUST_CFA_OFFSET -16
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CFI_RESTORE 15
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br %r14
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CFI_ENDPROC
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5: .quad 1000000000
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.long 274877907
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.size __kernel_gettimeofday,.-__kernel_gettimeofday
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