For bootloaders that support booting only ELF kernels and load only ELF
segments to memory there is no easy way to supply DTB without kernel
recompilation. For that purpose, create a section called .appended_dtb
that can be later updated with board-specific DTB using binutils e.g. at
kernel installation time.
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11114/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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>
Add an initial implementation of a proper (i.e. an ELF shared library)
VDSO. With this commit it does not export any symbols, it only replaces
the current signal return trampoline page. A later commit will add user
implementations of gettimeofday()/clock_gettime().
To support both new toolchains and old ones which don't generate ABI
flags section, we define its content manually and then use a tool
(genvdso) to patch up the section to have the correct name and type.
genvdso also extracts symbol offsets ({,rt_}sigreturn) needed by the
kernel, and generates a C file containing a "struct mips_vdso_image"
containing both the VDSO data and these offsets. This C file is
compiled into the kernel.
On 64-bit kernels we require a different VDSO for each supported ABI,
so we may build up to 3 different VDSOs. The VDSO to use is selected by
the mips_abi structure.
A kernel/user shared data page is created and mapped below the VDSO
image. This is currently empty, but will be used by the user time
function implementations which are added later.
[markos.chandras@imgtec.com:
- Add more comments
- Move abi detection in genvdso.h since it's the get_symbol function
that needs it.
- Add an R6 specific way to calculate the base address of VDSO in order
to avoid the branch instruction which affects performance.
- Do not patch .gnu.attributes since it's not needed for dynamic linking.
- Simplify Makefile a little bit.
- checkpatch fixes
- Restrict VDSO support for binutils < 2.25 for pre-R6
- Include atomic64.h for O32 variant on MIPS64]
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11337/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Prior to release 6 of the MIPS architecture it has been implementation
dependent whether masked interrupts cause a wait instruction to return,
so the kernel has effectively had to maintain a whitelist of cores upon
which it is safe to use the r4k_wait_irqoff cpu_wait implementation.
With MIPSr6 this is no longer implementation dependent and
r4k_wait_irqoff can always be used.
Remove the existing I6400 case which will no longer ever be hit, and was
incorrect anyway since I6400 & r6 in general doesn't have the WII bit.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11210/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Introduce mips_cm_lock_other & mips_cm_unlock_other, mirroring the
existing CPC equivalents, in order to lock access from the current core
to another via the core-other GCR region. This hasn't been required in
the past but with CM3 the CPC starts using GCR_CL_OTHER rather than
CPC_CL_OTHER and this will be required for safety.
[ralf@linux-mips.org: Fix merge conflict.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11207/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Provide support for outputting early debug information, in the form of
various register values should an exception occur, during the early
bringup of secondary cores. This code requires an ns16550-compatible
UART accessible from the secondary core, and is written in assembly due
to the environment in which such early exceptions occur where way may
not have a stack, be coherent or even have initialised caches.
[ralf@linux-mips.org: Fix merge conflict.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: linux-kernel@vger.kernel.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11202/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
OCTEON Pre-SDK-1.8.1 bootloaders can not handle PT_NOTE program headers,
so do not emit them.
Before the patch:
$ readelf --program-headers octeon-vmlinux
Elf file type is EXEC (Executable file)
Entry point 0xffffffff815d09d0
There are 2 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000001000 0xffffffff81100000 0xffffffff81100000
0x0000000000b57f80 0x0000000001b86360 RWE 1000
NOTE 0x00000000004e02e0 0xffffffff815df2e0 0xffffffff815df2e0
0x0000000000000024 0x0000000000000024 R 4
After the patch:
$ readelf --program-headers octeon-vmlinux
Elf file type is EXEC (Executable file)
Entry point 0xffffffff815d09d0
There are 1 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000001000 0xffffffff81100000 0xffffffff81100000
0x0000000000b57f80 0x0000000001b86360 RWE 1000
The patch was tested on DSR-1000N router.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11403/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Discard .MIPS.abiflags from vmlinux. It's not needed and will cause
issues e.g. with old OCTEON bootloaders that cannot tolerate
additional program headers.
Before the patch:
$ readelf --program-headers octeon-vmlinux
Elf file type is EXEC (Executable file)
Entry point 0xffffffff815d09d0
There are 3 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
ABIFLAGS 0x00000000005e77f0 0xffffffff816e67f0 0xffffffff816e67f0
0x0000000000000018 0x0000000000000018 R 8
LOAD 0x0000000000001000 0xffffffff81100000 0xffffffff81100000
0x0000000000b57f80 0x0000000001b86360 RWE 1000
NOTE 0x00000000004e02e0 0xffffffff815df2e0 0xffffffff815df2e0
0x0000000000000024 0x0000000000000024 R 4
After the patch:
$ readelf --program-headers octeon-vmlinux
Elf file type is EXEC (Executable file)
Entry point 0xffffffff815d09d0
There are 2 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000001000 0xffffffff81100000 0xffffffff81100000
0x0000000000b57f80 0x0000000001b86360 RWE 1000
NOTE 0x00000000004e02e0 0xffffffff815df2e0 0xffffffff815df2e0
0x0000000000000024 0x0000000000000024 R 4
Suggested-by: Matthew Fortune <matthew.fortune@imgtec.com>
Suggested-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Cc: David Daney <ddaney.cavm@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/11402/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
BCM7425 CPU Interface Zephyr Processor, pages 5-309 and 5-310
BCM7428B0 CPU Interface Zephyr Processor, pages 5-337 and 5-338
WAIT instruction:
Thread enters wait state. No instructions are executed until an
interrupt occurs. The processor's clocks are stopped if both threads
are in idle mode.
Description:
Execution of this instruction puts the thread into wait state, an idle
mode in which no instructions are fetched or executed. The thread remains
in wait state until an interrupt occurs that is not masked by the
interrupt mask field in the Status register. Then, if interrupts are
enabled by the IE bit in the Status register, the interrupt is serviced.
The ERET instruction returns to the instruction following the WAIT
instruction. If interrupts are disabled, the processor resumes executing
instructions with the next sequential instruction.
Programming notes:
The WAIT instruction should be executed while interrupts are disabled
by the IE bit in the Status register. This avoids a potential timing
hazard, which occurs if an interrupt is taken between testing the counter
and executing the WAIT instruction. In this hazard case, the interrupt
will have been completed before the WAIT instruction is executed, so
the processor will remain indefinitely in wait state until the next
interrupt.
Signed-off-by: Petri Gynther <pgynther@google.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: cernekee@gmail.com
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11322/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The MIPS syscall handler code used to return -ENOSYS on invalid
syscalls. Whilst this is expected, it caused problems for seccomp
filters because the said filters never had the change to run since
the code returned -ENOSYS before triggering them. This caused
problems on the chromium testsuite for filters looking for invalid
syscalls. This has now changed and the seccomp filters are always
run even if the syscall is invalid. We return -ENOSYS once we
return from the seccomp filters. Moreover, similar codepaths have
been merged in the process which simplifies somewhat the overall
syscall code.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11236/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Commit 1a3d59579b ("MIPS: Tidy up FPU context switching") removed FP
context saving from the asm-written resume function in favour of reusing
existing code to perform the same task. However it only removed the FP
context saving code from the r4k_switch.S implementation of resume.
Remove it from the r2300_switch.S implementation too in order to prevent
attempting to save the FP context twice, which would likely lead to an
exception from the second save because the FPU had already been disabled
by the first save.
This patch has only been build tested, using rbtx49xx_defconfig.
Fixes: 1a3d59579b ("MIPS: Tidy up FPU context switching")
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-kernel@vger.kernel.org
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/11167/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
R6 removed the Config4.MMUExtDef field, with the low 16 bits only
allowed to contain FTLB fields, and commit e87569cd6c ("MIPS:
cpu-probe: Fix VTLB/FTLB configuration for R6") updated the probing of
this field to assume an FTLB is always present for R6.
However the FTLB may still be absent. The presence of those fields is
actually specified by the MMU type in the Config.MT field, so use that
(the new cpu_has_ftlb) to determine whether the FTLB is actually
present.
Fixes: e87569cd6c ("MIPS: cpu-probe: Fix VTLB/FTLB configuration for R6")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11160/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Add cpu_has_ftlb, which specifies that an FTLB is present in addition to
the VTLB, probed based on whether Config.MT == 4 (rather than 1 for
standard JTLB).
This is necessary since MIPS release 6 removes Config4.MMUExtDef, so the
presence of the FTLB fields in Config4 must be determined from Config.MT
instead.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11159/
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
...
Pull locking and atomic updates from Ingo Molnar:
"Main changes in this cycle are:
- Extend atomic primitives with coherent logic op primitives
(atomic_{or,and,xor}()) and deprecate the old partial APIs
(atomic_{set,clear}_mask())
The old ops were incoherent with incompatible signatures across
architectures and with incomplete support. Now every architecture
supports the primitives consistently (by Peter Zijlstra)
- Generic support for 'relaxed atomics':
- _acquire/release/relaxed() flavours of xchg(), cmpxchg() and {add,sub}_return()
- atomic_read_acquire()
- atomic_set_release()
This came out of porting qwrlock code to arm64 (by Will Deacon)
- Clean up the fragile static_key APIs that were causing repeat bugs,
by introducing a new one:
DEFINE_STATIC_KEY_TRUE(name);
DEFINE_STATIC_KEY_FALSE(name);
which define a key of different types with an initial true/false
value.
Then allow:
static_branch_likely()
static_branch_unlikely()
to take a key of either type and emit the right instruction for the
case. To be able to know the 'type' of the static key we encode it
in the jump entry (by Peter Zijlstra)
- Static key self-tests (by Jason Baron)
- qrwlock optimizations (by Waiman Long)
- small futex enhancements (by Davidlohr Bueso)
- ... and misc other changes"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (63 commits)
jump_label/x86: Work around asm build bug on older/backported GCCs
locking, ARM, atomics: Define our SMP atomics in terms of _relaxed() operations
locking, include/llist: Use linux/atomic.h instead of asm/cmpxchg.h
locking/qrwlock: Make use of _{acquire|release|relaxed}() atomics
locking/qrwlock: Implement queue_write_unlock() using smp_store_release()
locking/lockref: Remove homebrew cmpxchg64_relaxed() macro definition
locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'
locking, asm-generic: Rework atomic-long.h to avoid bulk code duplication
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations
locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic
locking/static_keys: Make verify_keys() static
jump label, locking/static_keys: Update docs
locking/static_keys: Provide a selftest
jump_label: Provide a self-test
s390/uaccess, locking/static_keys: employ static_branch_likely()
x86, tsc, locking/static_keys: Employ static_branch_likely()
locking/static_keys: Add selftest
locking/static_keys: Add a new static_key interface
locking/static_keys: Rework update logic
locking/static_keys: Add static_key_{en,dis}able() helpers
...
It is desirable for signal handlers to be allowed to make use of MSA,
particularly if auto vectorisation is used when compiling a program.
The MSA context must therefore be saved & restored before & after
invoking the signal handler. Make use of the extended context structs
defined in the preceding patch to save MSA context after the sigframe
when appropriate.
[ralf@linux-mips.org: Fixed conflicts.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10796/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The context introduced by MSA needs to be saved around signals. However,
we can't increase the size of struct sigcontext because that will change
the offset of the signal mask in struct sigframe or struct ucontext.
This patch instead places the new context immediately after the struct
sigframe for traditional signals, or similarly after struct ucontext for
RT signals. The layout of struct sigframe & struct ucontext is identical
from their sigcontext fields onwards, so the offset from the sigcontext
to the extended context will always be the same regardless of the type
of signal.
Userland will be able to search through the extended context by using
the magic values to detect which types of context are present. Any
unrecognised context can be skipped over using the size field of struct
extcontext. Once the magic value END_EXTCONTEXT_MAGIC is seen it is
known that there are no further extended context structures to examine.
This approach is somewhat similar to that taken by ARM to save VFP &
other context at the end of struct ucontext.
Userland can determine whether extended context is present by checking
for the USED_EXTCONTEXT bit in the sc_used_math field of struct
sigcontext. Whilst this could potentially change the historic semantics
of sc_used_math if further extended context which does not imply FP
context were to be introduced in the future, I have been unable to find
any userland code making use of sc_used_math at all. Using one of the
fields described as unused in struct sigcontext was considered, but the
kernel does not already write to those fields so there would be no
guarantee of the field being clear on older kernels. Other alternatives
would be to have userland check the kernel version, or to have a HWCAP
bit indicating presence of extended context. However there is a desire
to have the context & information required to decode it be self
contained such that, for example, debuggers could decode the saved
context easily.
[ralf@linux-mips.org: Fixed conflict.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: Alex Smith <alex@alex-smith.me.uk>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10795/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The sc_used_math field of struct sigcontext & its variants has
traditionally been used as a boolean value indicating only whether or
not floating point context is saved within the sigcontext. With various
supported FP modes & the ability to switch between them this information
will no longer be enough to decode the meaning of the data stored in the
sc_fpregs fields of struct sigcontext.
To make that possible 3 bits are defined within sc_used_math:
- Bit 0 (USED_FP) represents whether FP was used, essentially
providing the boolean flag which sc_used_math as a whole provided
previously.
- Bit 1 (USED_FR1) provides the value of the Status.FR bit at the time
the FP context was saved.
- Bit 2 (USED_HYBRID_FPRS) indicates whether the FP context was saved
under the hybrid FPR scheme. Essentially, when set the odd singles
are located in bits 63:32 of the preceding even indexed sc_fpregs
element.
Any userland that tests whether the sc_used_math field is zero or
non-zero will continue to function as expected. Having said that, I
could not find any userland which uses the sc_used_math field at all.
[ralf@linux-mips.org: Fixed rejects.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10794/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
