47ce8527fb
Accessing raw timers (currently only CLOCK_MONOTONIC_RAW) through VDSO
doesn't return the correct time when using the GIC as clock source.
The address of the GIC mapped page is in this case not calculated
correctly. The GIC mapped page is calculated from the VDSO data by
subtracting PAGE_SIZE:
void *get_gic(const struct vdso_data *data) {
return (void __iomem *)data - PAGE_SIZE;
}
However, the data pointer is not page aligned for raw clock sources.
This is because the VDSO data for raw clock sources (CS_RAW = 1) is
stored after the VDSO data for coarse clock sources (CS_HRES_COARSE = 0).
Therefore, only the VDSO data for CS_HRES_COARSE is page aligned:
+--------------------+
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| vd[CS_RAW] | ---+
| vd[CS_HRES_COARSE] | |
+--------------------+ | -PAGE_SIZE
| | |
| GIC mapped page | <--+
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+--------------------+
When __arch_get_hw_counter() is called with &vd[CS_RAW], get_gic returns
the wrong address (somewhere inside the GIC mapped page). The GIC counter
values are not returned which results in an invalid time.
Fixes: a7f4df4e21 ("MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()")
Signed-off-by: Martin Fäcknitz <faecknitz@hotsplots.de>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2015 Imagination Technologies
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* Author: Alex Smith <alex.smith@imgtec.com>
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*/
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#include <asm/sgidefs.h>
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#ifndef __ASSEMBLY__
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#include <asm/asm.h>
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#include <asm/page.h>
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#include <asm/vdso.h>
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static inline unsigned long get_vdso_base(void)
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{
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unsigned long addr;
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/*
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* We can't use cpu_has_mips_r6 since it needs the cpu_data[]
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* kernel symbol.
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*/
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#ifdef CONFIG_CPU_MIPSR6
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/*
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* lapc <symbol> is an alias to addiupc reg, <symbol> - .
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*
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* We can't use addiupc because there is no label-label
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* support for the addiupc reloc
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*/
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__asm__("lapc %0, _start \n"
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: "=r" (addr) : :);
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#else
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/*
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* Get the base load address of the VDSO. We have to avoid generating
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* relocations and references to the GOT because ld.so does not peform
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* relocations on the VDSO. We use the current offset from the VDSO base
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* and perform a PC-relative branch which gives the absolute address in
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* ra, and take the difference. The assembler chokes on
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* "li %0, _start - .", so embed the offset as a word and branch over
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* it.
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*
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*/
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__asm__(
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" .set push \n"
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" .set noreorder \n"
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" bal 1f \n"
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" nop \n"
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" .word _start - . \n"
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"1: lw %0, 0($31) \n"
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" " STR(PTR_ADDU) " %0, $31, %0 \n"
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" .set pop \n"
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: "=r" (addr)
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:
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: "$31");
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#endif /* CONFIG_CPU_MIPSR6 */
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return addr;
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}
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static inline const struct vdso_data *get_vdso_data(void)
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{
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return (const struct vdso_data *)(get_vdso_base() - PAGE_SIZE);
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}
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#ifdef CONFIG_CLKSRC_MIPS_GIC
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static inline void __iomem *get_gic(const struct vdso_data *data)
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{
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return (void __iomem *)((unsigned long)data & PAGE_MASK) - PAGE_SIZE;
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}
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#endif /* CONFIG_CLKSRC_MIPS_GIC */
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#endif /* __ASSEMBLY__ */
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