Commit graph

997 commits

Author SHA1 Message Date
Peter Maydell 8c6afa6ab1 target-arm: A64: Correctly fault FP/Neon if CPACR.FPEN set
For the A64 instruction set, the only FP/Neon disable trap
is the CPACR FPEN bits, which may indicate "enabled", "disabled"
or "disabled for EL0". Add a bit to the AArch64 tb flags indicating
whether FP/Neon access is currently enabled and make the decoder
emit code to raise exceptions on use of FP/Neon insns if it is not.

We use a new flag in DisasContext rather than borrowing the
existing vfp_enabled flag because the A32/T32 decoder is going
to need both.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
---
I'm aware this is a rather hard to review patch; sorry.
I have done an exhaustive check that we have fp access checks
in all code paths with the aid of the assertions added in the
next patch plus the code-coverage hack patch I posted to the
list earlier.

This patch is correct as of
09e037354 target-arm: A64: Add saturating accumulate ops (USQADD/SUQADD)
which was the last of the Neon insns to be added, so assuming
no refactoring of the code it should be fine.
2014-04-17 21:34:03 +01:00
Rob Herring 00892383c9 target-arm: Provide syndrome information for MMU faults
Set up the required syndrome information when we detect an MMU fault.

Signed-off-by: Rob Herring <rob.herring@linaro.org>
[PMM: split out from exception handling patch, tweaked to bring
 in line with how we create other kinds of syndrome information]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
2014-04-17 21:34:03 +01:00
Peter Maydell d4a2dc675b target-arm: Add support for generating exceptions with syndrome information
Add new helpers exception_with_syndrome (for generating an exception
with syndrome information) and exception_uncategorized (for generating
an exception with "Unknown or Uncategorized Reason", which have a syndrome
register value of zero), and use them to generate the correct syndrome
information for exceptions which are raised directly from generated code.

This patch includes moving the A32/T32 gen_exception_insn functions
further up in the source file; they will be needed for "VFP/Neon disabled"
exception generation later.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
2014-04-17 21:34:03 +01:00
Peter Maydell 8bcbf37caa target-arm: Provide correct syndrome information for cpreg access traps
For exceptions taken to AArch64, if a coprocessor/system register
access fails due to a trap or enable bit then the syndrome information
must include details of the failing instruction (crn/crm/opc1/opc2
fields, etc). Make the decoder construct the syndrome information
at translate time so it can be passed at runtime to the access-check
helper function and used as required.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
2014-04-17 21:34:03 +01:00
Peter Maydell abf1172fc6 target-arm: Define exception record for AArch64 exceptions
For AArch32 exceptions, the only information provided about
the cause of an exception is the individual exception type (data
abort, undef, etc), which we store in cs->exception_index. For
AArch64, the CPU provides much more detail about the cause of
the exception, which can be found in the syndrome register.
Create a set of fields in CPUARMState which must be filled in
whenever an exception is raised, so that exception entry can
correctly fill in the syndrome register for the guest.
This includes the information which in AArch32 appears in
the DFAR and IFAR (fault address registers) and the DFSR
and IFSR (fault status registers) for data aborts and
prefetch aborts, since if we end up taking the MMU fault
to AArch64 rather than AArch32 this will need to end up
in different system registers.

This patch does a refactoring which moves the setting of the
AArch32 DFAR/DFSR/IFAR/IFSR from the point where the exception
is raised to the point where it is taken. (This is no change
for cores with an MMU, retains the existing clearly incorrect
behaviour for ARM946 of trashing the MP access permissions
registers which share the c5_data and c5_insn state fields,
and has no effect for v7M because we don't implement its
MPU fault status or address registers.)

As a side effect of the cleanup we fix a bug in the AArch64
linux-user mode code where we were passing a 64 bit fault
address through the 32 bit c6_data/c6_insn fields: it now
goes via the always-64-bit exception.vaddress.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
2014-04-17 21:34:03 +01:00
Peter Maydell c2b820fe58 target-arm: Implement AArch64 DAIF system register
Implement the DAIF system register which is a view of the
DAIF bits in PSTATE. To avoid needing a readfn, we widen
the daif field in CPUARMState to uint64_t.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
2014-04-17 21:34:03 +01:00
Peter Maydell ccd380876b target-arm: Split out private-to-target functions into internals.h
Currently cpu.h defines a mixture of functions and types needed by
the rest of QEMU and those needed only by files within target-arm/.
Split the latter out into a new header so they aren't needlessly
exposed further than required.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
2014-04-17 21:34:03 +01:00
Stefan Weil 6df05bdd17 target-arm: Add missing 'static' attribute
This fixes a warning from the static code analysis (smatch).

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2014-03-27 19:22:48 +04:00
Peter Maydell d108609bf9 target-arm: Fix A64 Neon MLS
The order of operands for the accumulate step in disas_simd_3same_int()
was reversed. This only affected the MLS instruction, since all the
other accumulating instructions in this category perform an addition
rather than a subtraction.

Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Tested-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-03-24 16:34:01 +00:00
Alex Bennée 09e037354b target-arm: A64: Add saturating accumulate ops (USQADD/SUQADD)
Add the saturating accumulate operations USQADD and SUQADD
to the A64 instruction set. This completes coverage of A64 Neon.
These operations (which are unsigned + signed -> signed and
signed + unsigned -> unsigned) don't exist in the A32/T32
instruction set, so require a complete new set of helper functions.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
2014-03-18 23:10:06 +00:00
Alex Bennée 0a79bc87c3 target-arm: A64: Add saturating int ops (SQNEG/SQABS)
This mostly re-uses the existing NEON helpers with an additional two for
the 64 bit case. I also took the opportunity to add TCG_CALL_NO_RWG
options to the helpers as they don't modify globals (saturation flags
are in the CPU Environment).

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
2014-03-18 23:10:06 +00:00
Alex Bennée c2fb418e35 target-arm: A64: Add [UF]RSQRTE (reciprocal root estimate)
This adds support for [UF]RSQRTE instructions. It utilises the existing
NEON helpers with some changes. The changes include an explicit passing
of fpstatus (so the correct one is used between arm32 and aarch64),
denormilzation, more correct error handling and also proper scaling of
the fraction going into the estimate.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-25-git-send-email-peter.maydell@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-03-17 16:31:53 +00:00
Peter Maydell 5553955eb6 target-arm: A64: Implement FCVTXN
Implement the FCVTXN operation, which does a narrowing fp precision
conversion using the "round to odd" (von Neumann) mode. This can
conveniently be implemented as "do operation using round to zero;
then set the LSB of the mantissa to 1 if the Inexact flag was set".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-24-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:53 +00:00
Alex Bennée 5201c13654 target-arm: A64: Implement scalar saturating narrow ops
This completes the set of integer narrowing saturating ops including:
     SQXTN, SQXTN2
     SQXTUN, SQXTUN2
     UQXTN, UQXTN2

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-23-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:52 +00:00
Alex Bennée 8b092ca9ef target-arm: A64: Move handle_2misc_narrow function
Move the handle_2misc_narrow() function up the file so that it can
be called from disas_simd_scalar_two_reg_misc().

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-22-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:52 +00:00
Alex Bennée b6d4443a7b target-arm: A64: Implement AdvSIMD reciprocal estimate insns URECPE, FRECPE
Implement URECPE and FRECPE instructions in both scalar and vector forms.
The actual reciprocal estimate function is shared with the A32/T32 Neon
code. However in A64 we aren't using the Neon "standard FPSCR value"
so extra checks are necessary to handle non-squashed denormal inputs
which can never happen for A32/T32. Calling conventions for the helpers
are thus modified to pass the fpst directly; we mark the helpers as
TCG_CALL_NO_RWG since we're changing the declarations anyway.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-21-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:52 +00:00
Peter Maydell 2ed3ea110f target-arm: A64: Implement FCVTZS, FCVTZU in the shift-imm categories
Implement FCVTZS and FCVTZU in the shift-imm and scalar-shift-imm
categories; this completes the implementation of those two groups.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-19-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:51 +00:00
Peter Maydell a847f32c04 target-arm: A64: Handle saturating left shifts SQSHL, SQSHLU, UQSHL
Implement the saturating left shift instructions SQSHL, SQSHLU
and UQSHL for the scalar-shift-imm and shift-imm categories.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-18-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:51 +00:00
Peter Maydell 03df01ed9a target-arm: A64: Implement FRINT*
Implement the FRINT* round-to-integral operations from
the 2-reg-misc category.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-16-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:50 +00:00
Peter Maydell 37a706adbf target-arm: A64: Implement SRI
Implement SRI (shift right and insert).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-15-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:50 +00:00
Alex Bennée 8f0c6758b0 target-arm: A64: Add FRECPX (reciprocal exponent)
These are fairly simple exponent only estimation functions using helpers.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-14-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:50 +00:00
Peter Maydell a566da1b02 target-arm: A64: List unsupported shift-imm opcodes
Add the remaining unsupported opcodes to the decode switches
for the shift-imm and scalar shift-imm categories so we can
see what is still to be implemented.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-13-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:50 +00:00
Peter Maydell 931c8cc270 target-arm: A64: Implement FCVTL
Implement FCVTL, the only instruction in the 2-reg-misc group
which widens from size to 2*size elements.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-12-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:49 +00:00
Peter Maydell 261a5b4dd1 target-arm: A64: Implement FCVTN
Implement FCVTN (narrowing fp-to-fp conversions) from the SIMD
2-reg-misc category.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-11-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:49 +00:00
Peter Maydell 04c7c6c261 target-arm: A64: Implement FCVT[NMAPZ][SU] SIMD instructions
Implement the floating-point-to-integer conversion instructions
FCVT[NMAPZ][SU] in the 2-reg-misc and scalar-2-reg-misc
categories.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-10-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:49 +00:00
Peter Maydell 73a81d10fd target-arm: A64: Implement SHLL, SHLL2
Implement the SHLL and SHLL2 instructions from the 2-reg-misc
category.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-9-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:49 +00:00
Peter Maydell 6781fa119f target-arm: A64: Implement SADDLP, UADDLP, SADALP, UADALP
Implement the SADDLP, UADDLP, SADALP and UADALP instructions
in the SIMD 2-reg misc category.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-8-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:48 +00:00
Alex Bennée c1b876b2e9 target-arm: A64: Saturating and narrowing shift ops
This implements the remaining [US][Q][R]SHR[U][N][2] opcodes, which are
saturating and narrowing shift right operations. These are used in
things like libav. Note signed shifts can have an "unsigned" saturating
narrow operation which will floor negative values.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1394822294-14837-7-git-send-email-peter.maydell@linaro.org
[PMM: Added the scalar encodings, style tweaks]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-03-17 16:31:48 +00:00
Alex Bennée b05c306857 target-arm: A64: Add remaining CLS/Z vector ops
Implement the CLS, CLZ operations in the 2-reg-misc category.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-6-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:48 +00:00
Alex Bennée f612537e07 target-arm: A64: Add FSQRT to C3.6.17 (two misc)
Implement FSQRT in the two-reg-misc category.
GCC uses this instruction form.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-5-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:47 +00:00
Alex Bennée 10113b6903 target-arm: A64: Add last AdvSIMD Integer to FP ops
This adds the remaining [US]CVTF operations to the SIMD
shift-immediate, scalar-shift-immediate, two-reg-misc and
scalar-two-reg-misc groups of opcodes.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1394822294-14837-4-git-send-email-peter.maydell@linaro.org
[PMM: added scalar 2-misc and scalar-shift-imm encodings]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-03-17 16:31:47 +00:00
Alex Bennée cf4ab1af29 target-arm: A64: Fix bug in add_sub_ext handling of rn
rn == 31 always means SP (not XZR) whether an add_sub_ext
instruction is setting the flags or not; only rd has behaviour
dependent on whether we are setting flags.

Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-3-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:47 +00:00
Peter Maydell a984e42c91 target-arm: A64: Implement PMULL instruction
Implement the PMULL instruction; this is the last unimplemented insn
in the three-reg-diff group.

Note that PMULL with size 3 is considered part of the AES part
of the crypto extensions (see the ID_AA64ISAR0_EL1 register definition
in the v8 ARM ARM), so it isn't necessary to burn an extra feature
bit on it, even though we're using more feature bits than a single
"crypto extension present/not present" toggle.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-2-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:47 +00:00
Peter Maydell d6d60581f3 target-arm: Add ARM_CP_IO notation to PMCR reginfo
Now that the PMCR writefn makes timer accesses, its reginfo needs
the ARM_CP_IO flag, so that icount mode works correctly. (Fixes
the bug accidentally introduced in commit 7c2cb42b).

Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1394908291-16546-1-git-send-email-peter.maydell@linaro.org
2014-03-17 16:31:46 +00:00
Stefan Weil 3b163b0165 misc: Fix typos in comments
Codespell found and fixed these new typos:

* doesnt -> doesn't
* funtion -> function
* perfomance -> performance
* remaing -> remaining

A coding style issue (line too long) was fixed manually.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2014-03-15 13:54:18 +04:00
Andreas Färber 0c591eb0a9 cputlb: Change tlb_set_page() argument to CPUState
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:52:47 +01:00
Andreas Färber 00c8cb0a36 cputlb: Change tlb_flush() argument to CPUState
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:52:47 +01:00
Andreas Färber 31b030d4ab cputlb: Change tlb_flush_page() argument to CPUState
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:52:47 +01:00
Andreas Färber a47dddd734 exec: Change cpu_abort() argument to CPUState
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:52:28 +01:00
Andreas Färber 3f38f309b2 translate-all: Change cpu_restore_state() argument to CPUState
This lets us drop some local variables in tlb_fill() functions.

Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:20:47 +01:00
Andreas Färber 5638d180d6 cpu-exec: Change cpu_loop_exit() argument to CPUState
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:20:47 +01:00
Andreas Färber d5a11fefef exec: Change tlb_fill() argument to CPUState
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:20:47 +01:00
Andreas Färber f0c3c505a8 cpu: Move breakpoints field from CPU_COMMON to CPUState
Most targets were using offsetof(CPUFooState, breakpoints) to determine
how much of CPUFooState to clear on reset. Use the next field after
CPU_COMMON instead, if any, or sizeof(CPUFooState) otherwise.

Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:20:47 +01:00
Andreas Färber 0429a97195 cpu: Move opaque field from CPU_COMMON to CPUState
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:20:47 +01:00
Andreas Färber 27103424c4 cpu: Move exception_index field from CPU_COMMON to CPUState
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:20:46 +01:00
Andreas Färber 7510454e3e cpu: Turn cpu_handle_mmu_fault() into a CPUClass hook
Note that while such functions may exist both for *-user and softmmu,
only *-user uses the CPUState hook, while softmmu reuses the prototype
for calling it directly.

Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:20:46 +01:00
Andreas Färber 9262685b81 cpu: Factor out cpu_generic_init()
All targets using it gain the ability to set -cpu name,key=value,...
options via the default TYPE_CPU CPUClass::parse_features() implementation.

Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:20:46 +01:00
Andreas Färber 8c2e1b0093 cpu: Turn cpu_has_work() into a CPUClass hook
Default to false.

Tidy variable naming and inline cast uses while at it.

Tested-by: Jia Liu <proljc@gmail.com> (or32)
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:01:49 +01:00
Andreas Färber 70d74660e7 target-arm: Clean up ENV_GET_CPU() usage
Commits ab1da85791,
fdfba1a298,
2c17449b30 added usages of ENV_GET_CPU()
macro to target-specific code.

Use arm_env_get_cpu() instead and enforce separating variable
declarations.

Cc: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-03-13 19:01:48 +01:00
Peter Maydell 72c1d3af6e target-arm: Implement WFE as a yield operation
Implement WFE to yield our timeslice to the next CPU.
This avoids slowdowns in multicore configurations caused
by one core busy-waiting on a spinlock which can't possibly
be unlocked until the other core has an opportunity to run.
This speeds up my test case A15 dual-core boot by a factor
of three (though it is still four or five times slower than
a single-core boot).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1393339545-22111-1-git-send-email-peter.maydell@linaro.org
Reviewed-by: Richard Henderson <rth@twiddle.net>
Tested-by: Rob Herring <rob.herring@linaro.org>
2014-03-10 14:56:30 +00:00