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David Miller d4926994be sparc: Fix JIT fused branch convergance. 
[ Upstream commit c44768a33d ]

On T4 and later sparc64 cpus we can use the fused compare and branch
instruction.

However, it can only be used if the branch destination is in the range
of a signed 10-bit immediate offset.  This amounts to 1024
instructions forwards or backwards.

After the commit referenced in the Fixes: tag, the largest possible
size program seen by the JIT explodes by a significant factor.

As a result of this convergance takes many more passes since the
expanded "BPF_LDX | BPF_MSH | BPF_B" code sequence, for example,
contains several embedded branch on condition instructions.

On each pass, as suddenly new fused compare and branch instances
become valid, this makes thousands more in range for the next pass.
And so on and so forth.

This is most greatly exemplified by "BPF_MAXINSNS: exec all MSH" which
takes 35 passes to converge, and shrinks the image by about 64K.

To decrease the cost of this number of convergance passes, do the
convergance pass before we have the program image allocated, just like
other JITs (such as x86) do.

Fixes: e0cea7ce98 ("bpf: implement ld_abs/ld_ind in native bpf")
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-12-13 08:51:52 +01:00
arch sparc: Fix JIT fused branch convergance. 2019-12-13 08:51:52 +01:00
block block: call rq_qos_exit() after queue is frozen 2019-12-01 09:17:06 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: ecc - check for invalid values in the key verification test 2019-12-13 08:51:24 +01:00
Documentation rtc: dt-binding: abx80x: fix resistance scale 2019-12-13 08:51:36 +01:00
drivers usb: dwc3: don't log probe deferrals; but do log other error codes 2019-12-13 08:51:46 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs f2fs: fix to allow node segment for GC by ioctl path 2019-12-13 08:51:51 +01:00
include ACPI: fix acpi_find_child_device() invocation in acpi_preset_companion() 2019-12-13 08:51:47 +01:00
init fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel audit: Embed key into chunk 2019-12-13 08:51:11 +01:00
lib lib/genalloc.c: include vmalloc.h 2019-12-05 09:21:05 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/vmstat.c: fix NUMA statistics updates 2019-12-13 08:51:27 +01:00
net net/ipv6: re-do dad when interface has IFF_NOARP flag change 2019-12-13 08:51:41 +01:00
samples vfio-mdev/samples: Use u8 instead of char for handle functions 2019-12-05 09:20:28 +01:00
scripts scripts/gdb: fix debugging modules compiled with hot/cold partitioning 2019-12-05 09:19:44 +01:00
security apparmor: delete the dentry in aafs_remove() to avoid a leak 2019-12-05 09:21:19 +01:00
sound ALSA: pcm: Fix stream lock usage in snd_pcm_period_elapsed() 2019-12-13 08:51:05 +01:00
tools selftests/powerpc: Skip test instead of failing 2019-12-13 08:51:45 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:57:16 +02:00
virt kvm: properly check debugfs dentry before using it 2019-12-05 09:21:14 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.88 2019-12-05 09:21:36 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.