When an instruction to save or restore a register from the stack fails
in _save_fp_context or _restore_fp_context return with -EFAULT. This
change was made to r2300_fpu.S[1] but it looks like it got lost with
the introduction of EX2[2]. This is also what the other implementation
of _save_fp_context and _restore_fp_context in r4k_fpu.S does, and
what is needed for the callers to be able to handle the error.
Furthermore calling do_exit(SIGSEGV) from bad_stack is wrong because
it does not terminate the entire process it just terminates a single
thread.
As the changed code was the only caller of arch/mips/kernel/syscall.c:bad_stack
remove the problematic and now unused helper function.
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Maciej Rozycki <macro@orcam.me.uk>
Cc: linux-mips@vger.kernel.org
[1] 35938a00ba ("MIPS: Fix ISA I FP sigcontext access violation handling")
[2] f92722dc45 ("MIPS: Correct MIPS I FP sigcontext layout")
Cc: stable@vger.kernel.org
Fixes: f92722dc45 ("MIPS: Correct MIPS I FP sigcontext layout")
Acked-by: Maciej W. Rozycki <macro@orcam.me.uk>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Link: https://lkml.kernel.org/r/20211020174406.17889-5-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
MIPS has up until now had 3 different ways for a task's floating point
context to be initialized:
- If the task's first use of FP involves it gaining ownership of an
FPU then _init_fpu() is used to initialize the FPU's registers such
that they all contain ~0, and the FPU registers will be stored to
struct thread_info later (eg. when context switching).
- If the task first uses FP on a CPU without an associated FPU then
fpu_emulator_init_fpu() initializes the task's floating point
register state in struct thread_info such that all floating point
register contain the bit pattern 0x7ff800007ff80000, different to
the _init_fpu() behaviour.
- If a task's floating point context is first accessed via ptrace then
init_fp_ctx() initializes the floating point register state in
struct thread_info to ~0, giving equivalent state to _init_fpu().
The _init_fpu() path has 2 separate implementations - one for r2k/r3k
style systems & one for r4k style systems. The _init_fpu() path also
requires that we be careful to clear & restore the value of the
Config5.FRE bit on modern systems in order to avoid inadvertently
triggering floating point exceptions.
None of this code is in a performance critical hot path - it runs only
the first time a task uses floating point. As such it doesn't seem to
warrant the complications of maintaining the _init_fpu() path.
Remove _init_fpu() & fpu_emulator_init_fpu(), instead using
init_fp_ctx() consistently to initialize floating point register state
in struct thread_info. Upon a task's first use of floating point this
will typically mean that we initialize state in memory & then load it
into FPU registers using _restore_fp() just as we would on a context
switch. For other paths such as __compute_return_epc_for_insn() or
mipsr2_decoder() this results in a significant simplification of the
work to be done.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21002/
Cc: linux-mips@linux-mips.org
Move _save_fp(), _restore_fp() & _init_fpu() out of r2300_switch.S &
into r2300_fpu.S. This logically places all FP-related asm code into
r2300_fpu.S & provides consistency with R4K after the preceding commit.
Besides cleaning up this will be useful for later patches which disable
FP support.
[ralf@linux-mips.org: Fixed build issues reported by Arnd Bergmann
<arnd@arndb.de>]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16238/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Complement commit 80cbfad790 ("MIPS: Correct MIPS I FP context
layout") and correct the way Floating Point General registers are stored
in a signal context with MIPS I hardware.
Use the S.D and L.D assembly macros to have pairs of SWC1 instructions
and pairs of LWC1 instructions produced, respectively, in an arrangement
which makes the memory representation of floating-point data passed
compatible with that used by hardware SDC1 and LDC1 instructions, where
available, regardless of the hardware endianness used. This matches the
layout used by r4k_fpu.S, ensuring run-time compatibility for MIPS I
software across all o32 hardware platforms.
Define an EX2 macro to handle exceptions from both hardware instructions
implicitly produced from S.D and L.D assembly macros.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14477/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Fix a regression introduced with commit 2db9ca0a35 ("MIPS: Use struct
mips_abi offsets to save FP context") for MIPS I/I FP signal contexts,
by converting save/restore code to the updated internal API. Start FGR
offsets from 0 rather than SC_FPREGS from $a0 and use $a1 rather than
the offset of SC_FPC_CSR from $a0 for the Floating Point Control/Status
Register (FCSR).
Document the new internal API and adjust assembly code formatting for
consistency.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14476/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Complement commit e50c0a8fa6 ("Support the MIPS32 / MIPS64 DSP ASE.")
and remove the Floating Point Implementation Register (FIR) from the FP
register set recorded in a signal context with MIPS I processors too, in
line with the change applied to r4k_fpu.S.
The `sc_fpc_eir' slot is unused according to our current ABI and the FIR
register is read-only and always directly accessible from user software.
[ralf@linux-mips.org: This is also required because the next commit depends
on it.]
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14475/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Complement commit 0ae8dceaebe3 ("Merge with 2.3.10.") and use the local
`fault' handler to recover from FP sigcontext access violation faults,
like corresponding code does in r4k_fpu.S. The `bad_stack' handler is
in syscall.c and is not suitable here as we want to propagate the error
condition up through the caller rather than killing the thread outright.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14474/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The target independent parts of the LLVM Lexer considers 'fault@function'
to be a single token representing the 'fault' symbol with a 'function'
modifier. However, this is not the case in the .type directive where
'function' refers to STT_FUNC from the ELF standard.
Although GAS accepts it, '.type symbol@function' is an undocumented form of
this directive. The documentation specifies a comma between the symbol and
'@function'.
Signed-off-by: Scott Egerton <Scott.Egerton@imgtec.com>
Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com>
Reviewed-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12587/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Starting with version 2.24.51.20140728 MIPS binutils complain loudly
about mixing soft-float and hard-float object files, leading to this
build failure since GCC is invoked with "-msoft-float" on MIPS:
{standard input}: Warning: .gnu_attribute 4,3 requires `softfloat'
LD arch/mips/alchemy/common/built-in.o
mipsel-softfloat-linux-gnu-ld: Warning: arch/mips/alchemy/common/built-in.o
uses -msoft-float (set by arch/mips/alchemy/common/prom.o),
arch/mips/alchemy/common/sleeper.o uses -mhard-float
To fix this, we detect if GAS is new enough to support "-msoft-float" command
option, and if it does, we can let GCC pass it to GAS; but then we also need
to sprinkle the files which make use of floating point registers with the
necessary ".set hardfloat" directives.
Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: Markos Chandras <Markos.Chandras@imgtec.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/8355/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Having received another series of whitespace patches I decided to do this
once and for all rather than dealing with this kind of patches trickling
in forever.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Removed obsolete stuff from arch makefile.
mips had a special rule for generating asm-offsets.h so preserved it
using an architecture specific hook in top-level Kbuild file.
Renamed .h file to asm-offsets.h
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Thomas Bogendoerfer