When emulating a jalr instruction with rd == $0, the code in
isBranchInstr was incorrectly writing to GPR $0 which should actually
always remain zeroed. This would lead to any further instructions
emulated which use $0 operating on a bogus value until the task is next
context switched, at which point the value of $0 in the task context
would be restored to the correct zero by a store in SAVE_SOME. Fix this
by not writing to rd if it is $0.
Fixes: 102cedc32a ("MIPS: microMIPS: Floating point support.")
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: stable <stable@vger.kernel.org> # v3.10
Patchwork: https://patchwork.linux-mips.org/patch/13160/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The code in _sp_maddf (formerly ieee754sp_madd) appears to have been
copied verbatim from ieee754sp_add, and although it's adding the
unpacked "r" & "z" floats it kept using macros that operate on "x" &
"y". This led to the addition being carried out incorrectly on some
mismash of the product, accumulator & multiplicand fields. Typically
this would lead to the assertions "ze == re" & "ze <= SP_EMAX" failing
since ze & re hadn't been operated upon.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Fixes: e24c3bec3e ("MIPS: math-emu: Add support for the MIPS R6 MADDF FPU instruction")
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: 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/13159/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
A line incrementing the re variable was indented a level too deep in
ieee754dp_mul, making the code unclear to read. Fix the indentation.
This appears to have been copied verbatim along with the rest of the
multiplication code to ieee754dp_maddf, now _dp_maddf, too so fix the
indentation there too.
Signed-off-by: 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/13158/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
A comment in ieee754dp_mul indicates that the code is about to perform a
32b x 32b multiplication & keep the high 32b of the result. It appears
this was copied from the single-precision multiplication code, since the
code actually goes on to perform a 64b x 64b multiplication & keep the
high 64b of the result. Fix the comment to indicate 64b.
It appears also that this comment was copied verbatim along with the
rest of the multiplication code into ieee754dp_maddf, which has since
been renamed _dp_maddf. Fix the same issue there.
Signed-off-by: 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/13157/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Introduce macros for handling the "z" argument to maddf & msubf, making
its handling consistent with that of the "x" & "y" arguments rather than
open-coding equivalents.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: 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/13156/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The code for emulating MIPSr6 madd.d & msub.d instructions has
previously been implemented as 2 different functions, namely
ieee754dp_maddf & ieee754dp_msubf. The difference in behaviour of these
2 instructions is merely the sign of the product, so we can easily share
the code implementing them. Do this for the double precision variant,
removing the original ieee754dp_msubf in favor of reusing the code from
ieee754dp_maddf.
Signed-off-by: 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/13155/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The code for emulating MIPSr6 madd.s & msub.s instructions has
previously been implemented as 2 different functions, namely
ieee754sp_maddf & ieee754sp_msubf. The difference in behaviour of these
2 instructions is merely the sign of the product, so we can easily share
the code implementing them. Do this for the single precision variant,
removing the original ieee754sp_msubf in favor of reusing the code from
ieee754sp_maddf.
Signed-off-by: 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/13154/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Add support for emulating the MIPSr6 sel.fmt instruction, which was
previously missing from the FPU emulation code. This instruction selects
its result from 2 possible source registers, based upon bit 0 of the
destination register, and is valid only for S (single) & D (double) data
types.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13153/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The conditions for branching when emulating the BC1EQZ & BC1NEZ
instructions were backwards, leading to each of those instructions being
treated as the other. Fix this by reversing the conditions, and clear up
the code a little for readability & checkpatch.
Fixes: c909ca718e ("MIPS: math-emu: Emulate missing BC1{EQ,NE}Z instructions")
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: 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/13150/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Propagate sNaN payload in quieting in the legacy-NaN mode as well. If
clearing the quiet bit would produce infinity, then set the next lower
trailing significand field bit, matching the SB-1 and BMIPS5000 hardware
implementations. Some other MIPS FPU hardware implementations do
produce the default qNaN bit pattern instead.
This reverts some changes made for semantics preservation with commit
dc3ddf42 [MIPS: math-emu: Update sNaN quieting handlers], consequently
bringing back most of the semantics from before commit fdffbafb [Lots of
FPU bug fixes from Kjeld Borch Egevang.], except from the qNaN produced
in the infinity case. Previously the default qNaN bit pattern was
produced in that case.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11483/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Remove irrelevant content from the description of the emulation frame in
`mips_dsemul', referring to bare-metal configurations. Update the text,
reflecting the change made with commit ba3049ed40 ("MIPS: Switch FPU
emulator trap to BREAK instruction."), where we switched from using an
address error exception on an unaligned access to the use of a BREAK 514
instruction causing a breakpoint exception instead.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12176/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Emulate the microMIPS ADDIUPC instruction directly in `mips_dsemul'. If
executed in the emulation frame, this instruction produces an incorrect
result, because the value of the PC there is not the same as where the
instruction originated.
Reshape code so as to handle all microMIPS cases together.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12175/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Complement commit 102cedc32a ("MIPS: microMIPS: Floating point
support.") which introduced microMIPS FPU emulation, but did not adjust
the encoding of the BREAK instruction used to terminate the branch delay
slot emulation frame. Consequently the execution of any such frame is
indeterminate and, depending on CPU configuration, will result in random
code execution or an offending program being terminated with SIGILL.
This is because the regular MIPS BREAK instruction is encoded with the 0
major and the 0xd minor opcode, however in the microMIPS instruction set
this major/minor opcode pair denotes an encoding reserved for the DSP
ASE. Instead the microMIPS BREAK instruction is encoded with the 0
major and the 0x7 minor opcode.
Use the correct BREAK encoding for microMIPS FPU emulation then.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12174/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Correct formatting breakage introduced with commit 102cedc32a ("MIPS:
microMIPS: Floating point support."), so that further changes to this
code can be consistent.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12173/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Fix an issue introduced with commit 9ab4471c9f ("MIPS: math-emu:
Correct delay-slot exception propagation") where the emulation of a NOP
instruction signals the need to terminate the emulation loop. This in
turn, if the PC has not changed from the entry to the loop, will cause
the kernel to terminate the program with SIGILL.
Consider this program:
static double div(double d)
{
do
d /= 2.0;
while (d > .5);
return d;
}
int main(int argc, char **argv)
{
return div(argc);
}
which gets compiled to the following binary code:
00400490 <main>:
400490: 44840000 mtc1 a0,$f0
400494: 3c020040 lui v0,0x40
400498: d44207f8 ldc1 $f2,2040(v0)
40049c: 46800021 cvt.d.w $f0,$f0
4004a0: 46220002 mul.d $f0,$f0,$f2
4004a4: 4620103c c.lt.d $f2,$f0
4004a8: 4501fffd bc1t 4004a0 <main+0x10>
4004ac: 00000000 nop
4004b0: 4620000d trunc.w.d $f0,$f0
4004b4: 03e00008 jr ra
4004b8: 44020000 mfc1 v0,$f0
4004bc: 00000000 nop
Where the FPU emulator is used, depending on the number of command-line
arguments this code will either run to completion or terminate with
SIGILL.
If no arguments are specified, then BC1T will not be taken, NOP will not
be emulated and code will complete successfully.
If one argument is specified, then BC1T will be taken once and NOP will
be emulated. At this point the entry PC value will be 0x400498 and the
new PC value, set by `mips_dsemul' will be 0x4004a0, the target of BC1T.
The emulation loop will terminate, but SIGILL will not be issued,
because the PC has changed. The FPU emulator will be entered again and
on the second execution BC1T will not be taken, NOP will not be emulated
and code will complete successfully.
If two or more arguments are specified, then the first execution of BC1T
will proceed as above. Upon reentering the FPU emulator the emulation
loop will continue to BC1T, at which point the branch will be taken and
NOP emulated again. At this point however the entry PC value will be
0x4004a0, the same as the target of BC1T. This will make the emulator
conclude that execution has not advanced and therefore an unsupported
FPU instruction has been encountered, and SIGILL will be sent to the
process.
Fix the problem by extending the internal API of `mips_dsemul', making
it return -1 if no delay slot emulation frame has been made, the
instruction has been handled and execution of the emulation loop needs
to continue as if nothing happened. Remove code from `mips_dsemul' to
reproduce steps made by the emulation loop at the conclusion of each
iteration, as those will be reached normally now. Adjust call sites
accordingly. Document the API.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12172/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Implement IEEE Std 754-2008 NaN encoding wired to the state of the
FCSR.NAN2008 bit. Make the interpretation of the quiet bit in NaN data
as follows:
* in the legacy mode originally defined by the MIPS architecture the
value of 1 denotes an sNaN whereas the value of 0 denotes a qNaN,
* in the 2008 mode introduced with revision 5 of the MIPS architecture
the value of 0 denotes an sNaN whereas the value of 1 denotes a qNaN,
following the definition of the preferred NaN encoding introduced with
IEEE Std 754-2008.
In the 2008 mode, following the requirement of the said standard, quiet
an sNaN where needed by setting the quiet bit to 1 and leaving all the
NaN payload bits unchanged.
Update format conversion operations according to the rules set by IEEE
Std 754-2008 and the MIPS architecture. Specifically:
* propagate NaN payload bits through conversions between floating-point
formats such that as much information as possible is preserved and
specifically a conversion from a narrower format to a wider format and
then back to the original format does not change a qNaN payload in any
way,
* conversions from a floating-point to an integer format where the
source is a NaN, infinity or a value that would convert to an integer
outside the range of the result format produce, under the default
exception handling, the respective values defined by the MIPS
architecture.
In full FPU emulation set the FIR.HAS2008 bit to 1, however do not make
any further FCSR bits writable.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11477/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Implement IEEE Std 754-2008 non-arithmetic ABS.fmt and NEG.fmt emulation
wired to the state of the FCSR.ABS2008 bit. In the non-arithmetic mode
the sign bit is altered according to the operation requested regardless
of the datum encoded in the input operand, no other bits are changed,
the resulting bit pattern is written to the output operand and no
exception is ever signalled.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11476/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
We have many extern declarations of mips_debugfs_dir through arch/mips/
in various C files. Unify them by declaring mips_debugfs_dir in a
header, including it in each affected C file & removing the duplicate
declarations.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-kernel@vger.kernel.org
Cc: Joe Perches <joe@perches.com>
Cc: Jaedon Shin <jaedon.shin@gmail.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: James Cowgill <James.Cowgill@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11181/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
handle_dsemul does not exist and it's not being used in the code at all
so remove its declaration. The deliberate DS emulation exception is
handled by the do_dsemulret C code.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10950/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
MIPS R6 introduced the following instruction:
Scalar Floating-Point Maximum and
Scalar Floating-Point argument with Maximum Absolute Value
MAX.fmt writes the maximum value of the inputs fs and ft to the
destination fd.
MAXA.fmt takes input arguments fs and ft and writes the argument with
the maximum absolute value to the destination fd.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10961/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
MIPS R6 introduced the following instruction:
Scalar Floating-Point Minimum and
Scalar Floating-Point argument with Minimum Absolute Value
MIN.fmt writes the minimum value of the inputs fs and ft to the
destination fd.
MINA.fmt takes input arguments fs and ft and writes the argument with
the minimum absolute value to the destination fd.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10960/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
MIPS R6 introduced the following instruction:
Stores in fd a bit mask reflecting the floating-point class of the
floating point scalar value fs.
CLASS.fmt: FPR[fd] = class(FPR[fs])
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10959/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
MIPS R6 introduced the following instruction:
Floating-Point Round to Integral
Scalar floating-point round to integral floating point value.
RINT.fmt: FPR[fd] = round_int(FPR[fs])
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10958/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
MIPS R6 introduced the following instruction:
SELNEZ.fmt: FPR[fd] FPR[ft].bit0 ? FPR[fs] : 0
Add support for emulating the single and double precision
formats of the said instruction.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10955/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
MIPS R6 introduced the following instruction:
SELEQZ.fmt: FPR[fd] FPR[ft].bit0 ? 0 : FPR[fs]
Add support for emulating the single and double precision formats
of the said instruction.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10954/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Add support for emulating the new CMP.condn.fmt R6 instructions and
return SIGILL for the old C.cond.fmt if R2 emulation is not enabled
since it's not supported by R6.
The functionality of the new CMP.condn.fmt is the following one:
If the comparison specified by the condn field of the instruction
is true for the operand values, the result is true; otherwise, the
result is false. If no exception is taken, the result is written into
FPR fd; true is all 1s and false is all 0s repeated the operand width
of fmt. All other bits beyond the operand width fmt are UNPREDICTABLE.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10953/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Commit c8a34581ec ("MIPS: Emulate the BC1{EQ,NE}Z FPU instructions")
added support for emulating the new R6 BC1{EQ,NE}Z branches but it missed
the case where the instruction that caused the exception was not on a DS.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Fixes: c8a34581ec ("MIPS: Emulate the BC1{EQ,NE}Z FPU instructions")
Cc: <stable@vger.kernel.org> # 4.0+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10738/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The mfhc/mthc instructions are supported on MIPS R6 so emulate
them if needed.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # 4.0+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10737/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The double format (d_fmt) case uses an opening bracket which then
closes at the end of the word format (w_fmt). This can be rather confusing
so add the closing bracket at the end of the d_fmt case and use another one
for the w_fmt one.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10733/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Commit 5f9f41c474 ("MIPS: kernel: Prepare
the JR instruction for emulation on MIPS R6") added support for
emulating the JR instruction on MIPS R6 cores but that introduced a bug
which could be triggered when hitting a JALR opcode because the code used
the wrong field in the 'r_format' struct to determine the instruction
opcode. This lead to crashes because an emulated JALR instruction was
treated as a JR one when the R6 emulator was turned off.
Fixes: 5f9f41c474 ("MIPS: kernel: Prepare the JR instruction for emulation on MIPS R6")
Cc: <stable@vger.kernel.org> # 4.0+
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10583/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Commits f1b44067c1 ("MIPS: Emulate the
new MIPS R6 B{L,G}T{Z,}{AL,}C instructions") and commit
a8ff66f52d ("MIPS: Emulate the new MIPS
R6 B{L,G}E{Z,}{AL,}C instructions") added support for emulating various
branch compact instructions. However, it missed the case for those which
use the old BLEZL and BGTZL opcodes leading to random crashes when the R6
emulator is disabled. We fix this by ensuring that the 'rt' field is not
zero which is always true for these branch compact instructions.
Fixes: f1b44067c1 ("MIPS: Emulate the new MIPS R6 B{L,G}T{Z,}{AL,}C instructions")
Fixes: a8ff66f52d ("MIPS: Emulate the new MIPS R6 B{L,G}E{Z,}{AL,}C instructions")
Cc: <stable@vger.kernel.org> # 4.0+
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/10582/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Fix "BUG: using smp_processor_id() in preemptible" reported in accesses
to thread's FPU defaults: the value to initialise FSCR to at program
startup, the FCSR r/w mask and the contents of FIR in full FPU
emulation, removing a regression introduced with 9b26616c [MIPS: Respect
the ISA level in FCSR handling] and f6843626 [MIPS: math-emu: Set FIR
feature flags for full emulation].
Use `boot_cpu_data' to obtain the data from, following the approach that
`cpu_has_*' macros take and avoiding the call to `smp_processor_id' made
in the reference to `current_cpu_data'. The contents of FSCR have to be
consistent across processors in an SMP system, the settings there must
not change as a thread is migrated across processors. And the contents
of FIR are guaranteed to be consistent in FPU emulation, by definition.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Tested-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Tested-by: Paul Martin <paul.martin@codethink.co.uk>
Cc: Markos Chandras <Markos.Chandras@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10030/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Define the central place the default FCSR value is set from, initialised
in `cpu_probe'. Determine the FCSR mask applied to values written to
the register with CTC1 in the full emulation mode and via ptrace(2),
according to the ISA level of processor hardware or the writability of
bits 31:18 if actual FPU hardware is used.
Software may rely on FCSR bits whose functions our emulator does not
implement, so it should not allow them to be set or software may get
confused. For ptrace(2) it's just sanity.
[ralf@linux-mips.org: Fixed double inclusion of <asm/current.h>.]
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9711/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The ABS.fmt and NEG.fmt instructions have been specified as arithmetic
in the MIPS architecture, which in particular implies handling NaN data
in the usual way with qNaN bit patterns propagated unchanged and sNaN
bit patterns signalling the usual IEEE 754 Invalid Operation exception
and quieted by default.
A series of changes applied over time to our implementation:
c5033d78 [MIPS] ieee754[sd]p_neg workaround
cea2be44 MIPS: Fix abs.[sd] and neg.[sd] emulation for NaN operands
has led to the current situation where the sign bit is updated according
to the operation requested even for NaN inputs. This is according to
these commits a workaround so that broken binaries produced by GCC
disregarding the properties of these instructions have a chance to work.
For sNaN inputs this remains within IEEE Std 754 as the standard leaves
the choice of output qNaN bit patterns produced under the default
Invalid Operation exception handling for individual sNaN input bit
patterns to implementer's discretion, even though it still recommends as
much NaN input information to be preserved in NaN outputs.
For qNaN inputs however it violates the standard as it requires a qNaN
input bit patterns to propagate unchanged to output.
This is also unlike real MIPS FPU hardware behaves where sNaN and/or
qNaN processing has been fully implemented with no Unimplemented
Operation exception signalled. Such hardware propagates any input qNaN
bit pattern unchanged. It also quiets any input sNaN bit pattern in an
implementer-specific manner, for example the MIPS 74Kf processor returns
the default qNaN pattern with the sign bit always clear and the Broadcom
SB-1 and BMIPS5000 processors propagate the input sNaN bit pattern with
the sign bit unchanged and the quiet bit first cleared in the trailing
significand field and then the next lower bit set if clearing the quiet
bit left the field with no other bit set.
Especially the latter observation indicates the limited usefulness of
the workaround as it will cover many hardware configurations, but not
all of them, only making it harder to discover such broken binaries that
need to be recompiled with GCC told to avoid the use of ABS.fmt and
NEG.fmt instructions where non-arithmetic semantics is required by the
algorithm used.
Revert the damage done by the series of changes then, and take the
opportunity to simplify implementation by calling `ieee754dp_sub' and
`ieee754dp_add' as required and also the rounding mode set towards -Inf
temporarily so that the sign of 0 is correctly handled.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9710/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Define IEEE 754-2008 feature control bits: FIR.HAS2008, FCSR.ABS2008 and
FCSR.NAN2008, and update the `_ieee754_csr' structure accordingly.
For completeness define FIR.UFRP too.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9709/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Implement the FCCR, FEXR and FENR "shadow" FPU registers for the
architecture levels that include them, for the CFC1 and CTC1
instructions in the full emulation mode.
For completeness add macros for the CP1 UFR and UNFR registers too, no
actual implementation though.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9708/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Implement FIR feature flags in the FPU emulator according to features
supported and architecture level requirements. The W, L and F64 bits
have only been added at level #2 even though the features they refer to
were also included with the MIPS64r1 ISA and the W fixed-point format
also with the MIPS32r1 ISA.
This is only relevant for the full emulation mode and the emulated CFC1
instruction as well as ptrace(2) accesses.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9707/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Complement 593d33fe [MIPS: math-emu: Move various objects into an ar
library.] and also move sp_tlong.o, sp_flong.o, dp_tlong.o, and
dp_flong.o into an `ar' library. These objects implement long
fixed-point format support that can be omitted from MIPS I, MIPS II and
MIPS32r1 configurations.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9702/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Restore EPC at the branch whose delay slot is emulated if the delay-slot
instruction signals. This is so that code in `fpu_emulator_cop1Handler'
does not see EPC having advanced and mistakenly successfully resume
userland execution from the location at the branch target in that case.
Restoring EPC guarantees an immediate exit from the emulation loop and
if EPC hasn't advanced at all since entering the loop, also issuing the
signal reported by the delay-slot instruction.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9701/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Correct ISA requirements for floating-point instructions:
* the CU3 exception signifies a real COP3 instruction in MIPS I & II,
* the BC1FL and BC1TL instructions are not supported in MIPS I,
* the SQRT.fmt instructions are indeed supported in MIPS II,
* the LDC1 and SDC1 instructions are indeed supported in MIPS32r1,
* the CEIL.W.fmt, FLOOR.W.fmt, ROUND.W.fmt and TRUNC.W.fmt instructions
are indeed supported in MIPS32,
* the CVT.L.fmt and CVT.fmt.L instructions are indeed supported in
MIPS32r2 and MIPS32r6,
* the CEIL.L.fmt, FLOOR.L.fmt, ROUND.L.fmt and TRUNC.L.fmt instructions
are indeed supported in MIPS32r2 and MIPS32r6,
* the RSQRT.fmt and RECIP.fmt instructions are indeed supported in
MIPS64r1,
Also simplify conditionals for MIPS III and MIPS IV FPU instructions and
the handling of the MOVCI minor opcode.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9700/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Correct a cache coherency regression introduced with be1664c4 [Another
round of fixes for the fp emulator.] for the emulation frame used in
delay-slot emulation.
Two instructions are copied into the frame and as from the commit
referred a cache synchronisation call is made for the second instruction
aka `badinst' of the two only. The `flush_cache_sigtramp' interface is
reused that guarantees that synchronisation will be made for 8 bytes or
2 instructions starting from the address requested, although if cache
lines are wider then a larger area may be synchronised.
Change the call to point to the first of the two instructions aka `emul'
instead, removing unpredictable behaviour resulting from cache
incoherency.
This bug only ever manifested itself on systems implementing 4-byte
cache lines, typically MIPS I systems, causing all kinds of weirdness.
This is because the sequence of two instructions starting from `emul' is
8-byte aligned and for 8-byte or wider cache lines the line synchronised
will span both, so the vast majority of systems have escaped unharmed.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9698/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The `ieee754sp_isnan' and `ieee754dp_isnan' NaN classifiers are now no
longer externally referred, remove their header prototypes and make them
local to the two only respective places still making use of them.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9693/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Rewrite qNaN handling in `ieee754sp_fdp' using the `ieee754_class_nan'
helper recently added, removing the external call to `ieee754sp_isnan'
and reducing the size of code by 16 instructions or 64 bytes.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9692/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
