Add user-mode implementations of gettimeofday() and clock_gettime() to
the VDSO. This is currently usable with 2 clocksources: the CP0 count
register, which is accessible to user-mode via RDHWR on R2 and later
cores, or the MIPS Global Interrupt Controller (GIC) timer, which
provides a "user-mode visible" section containing a mirror of its
counter registers. This section must be mapped into user memory, which
is done below the VDSO data page.
When a supported clocksource is not in use, the VDSO functions will
return -ENOSYS, which causes libc to fall back on the standard syscall
path.
When support for neither of these clocksources is compiled into the
kernel at all, the VDSO still provides clock_gettime(), as the coarse
realtime/monotonic clocks can still be implemented. However,
gettimeofday() is not provided in this case as nothing can be done
without a suitable clocksource. This causes the symbol lookup to fail
in libc and it will then always use the standard syscall path.
This patch includes a workaround for a bug in QEMU which results in
RDHWR on the CP0 count register always returning a constant (incorrect)
value. A fix for this has been submitted, and the workaround can be
removed after the fix has been in stable releases for a reasonable
amount of time.
A simple performance test which calls gettimeofday() 1000 times in a
loop and calculates the average execution time gives the following
results on a Malta + I6400 (running at 20MHz):
- Syscall: ~31000 ns
- VDSO (GIC): ~15000 ns
- VDSO (CP0): ~9500 ns
[markos.chandras@imgtec.com:
- Minor code re-arrangements in order for mappings to be made
in the order they appear to the process' address space.
- Move do_{monotonic, realtime} outside of the MIPS_CLOCK_VSYSCALL ifdef
- Use gic_get_usm_range so we can do the GIC mapping in the
arch/mips/kernel/vdso instead of the GIC irqchip driver]
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11338/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull MIPS updates from Ralf Baechle:
"This is the main pull request for 4.3 for MIPS. Here's the summary:
Three fixes that didn't make 4.2-stable:
- a -Os build might compile the kernel using the MIPS16 instruction
set but the R2 optimized inline functions in <uapi/asm/swab.h> are
implemented using 32-bit wide instructions which is invalid.
- a build error in pgtable-bits.h for a particular kernel
configuration.
- accessing registers of the CM GCR might have been compiled to use
64 bit accesses but these registers are onl 32 bit wide.
And also a few new bits:
- move the ATH79 GPIO driver to drivers/gpio
- the definition of IRQCHIP_DECLARE has moved to linux/irqchip.h,
change ATH79 accordingly.
- fix definition of pgprot_writecombine
- add an implementation of dma_map_ops.mmap
- fix alignment of quiet build output for vmlinuz link
- BCM47xx: Use kmemdup rather than duplicating its implementation
- Netlogic: Fix 0x0x prefixes of constants.
- merge Bjorn Helgaas' series to remove most of the weak keywords
from function declarations.
- CP0 and CP1 registers are best considered treated as unsigned
values to avoid large values from becoming negative values.
- improve support for the MIPS GIC timer.
- enable common clock framework for Malta and SEAD3.
- a number of improvments and fixes to dump_tlb().
- document the MIPS TLB dump functionality in Magic SysRq.
- Cavium Octeon CN68XX improvments.
- NetLogic improvments.
- irq: Use access helper irq_data_get_affinity_mask.
- handle MSA unaligned accesses.
- a number of R6-related math-emu fixes.
- support for I6400.
- improvments to MSA support.
- add uprobes support.
- move from deprecated __initcall to arch_initcall.
- remove finish_arch_switch().
- IRQ cleanups by Thomas Gleixner.
- migrate to new 'set-state' interface.
- random small cleanups"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (148 commits)
MIPS: UAPI: Fix unrecognized opcode WSBH/DSBH/DSHD when using MIPS16.
MIPS: Fix alignment of quiet build output for vmlinuz link
MIPS: math-emu: Remove unused handle_dsemul function declaration
MIPS: math-emu: Add support for the MIPS R6 MAX{, A} FPU instruction
MIPS: math-emu: Add support for the MIPS R6 MIN{, A} FPU instruction
MIPS: math-emu: Add support for the MIPS R6 CLASS FPU instruction
MIPS: math-emu: Add support for the MIPS R6 RINT FPU instruction
MIPS: math-emu: Add support for the MIPS R6 MSUBF FPU instruction
MIPS: math-emu: Add support for the MIPS R6 MADDF FPU instruction
MIPS: math-emu: Add support for the MIPS R6 SELNEZ FPU instruction
MIPS: math-emu: Add support for the MIPS R6 SELEQZ FPU instruction
MIPS: math-emu: Add support for the CMP.condn.fmt R6 instruction
MIPS: inst.h: Add new MIPS R6 FPU opcodes
MIPS: Octeon: Fix management port MII address on Kontron S1901
MIPS: BCM47xx: Use kmemdup rather than duplicating its implementation
STAGING: Octeon: Use common helpers for determining interface and port
MIPS: Octeon: Support interfaces 4 and 5
MIPS: Octeon: Set up 1:1 mapping between CN68XX PKO queues and ports
MIPS: Octeon: Initialize CN68XX PKO
STAGING: Octeon: Support CN68XX style WQE
...
Migrate mips-gic driver to the new 'set-state' interface provided by
clockevents core, the earlier 'set-mode' interface is marked obsolete
now.
This also enables us to implement callbacks for new states of clockevent
devices, for example: ONESHOT_STOPPED.
We weren't doing anything in the ->set_mode() callback. So, this patch
doesn't provide any set-state callbacks.
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
