LoongArch: Add ORC stack unwinder support

The kernel CONFIG_UNWINDER_ORC option enables the ORC unwinder, which is
similar in concept to a DWARF unwinder. The difference is that the format
of the ORC data is much simpler than DWARF, which in turn allows the ORC
unwinder to be much simpler and faster.

The ORC data consists of unwind tables which are generated by objtool.
After analyzing all the code paths of a .o file, it determines information
about the stack state at each instruction address in the file and outputs
that information to the .orc_unwind and .orc_unwind_ip sections.

The per-object ORC sections are combined at link time and are sorted and
post-processed at boot time. The unwinder uses the resulting data to
correlate instruction addresses with their stack states at run time.

Most of the logic are similar with x86, in order to get ra info before ra
is saved into stack, add ra_reg and ra_offset into orc_entry. At the same
time, modify some arch-specific code to silence the objtool warnings.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Co-developed-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Add KASAN (Kernel Address Sanitizer) support

1/8 of kernel addresses reserved for shadow memory. But for LoongArch,
There are a lot of holes between different segments and valid address
space (256T available) is insufficient to map all these segments to kasan
shadow memory with the common formula provided by kasan core, saying
(addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET

So LoongArch has a arch-specific mapping formula, different segments are
mapped individually, and only limited space lengths of these specific
segments are mapped to shadow.

At early boot stage the whole shadow region populated with just one
physical page (kasan_early_shadow_page). Later, this page is reused as
readonly zero shadow for some memory that kasan currently don't track.
After mapping the physical memory, pages for shadow memory are allocated
and mapped.

Functions like memset()/memcpy()/memmove() do a lot of memory accesses.
If bad pointer passed to one of these function it is important to be
caught. Compiler's instrumentation cannot do this since these functions
are written in assembly.

KASan replaces memory functions with manually instrumented variants.
Original functions declared as weak symbols so strong definitions in
mm/kasan/kasan.c could replace them. Original functions have aliases
with '__' prefix in names, so we could call non-instrumented variant
if needed.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Replace #include <asm/export.h> with #include <linux/export.h>

Commit ddb5cdbafaaad ("kbuild: generate KSYMTAB entries by modpost")
deprecated <asm/export.h>, which is now a wrapper of <linux/export.h>.

Replace #include <asm/export.h> with #include <linux/export.h>.

After all the <asm/export.h> lines are converted, <asm/export.h> and
<asm-generic/export.h> will be removed.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Optimize memory ops (memset/memcpy/memmove)

To optimize memset()/memcpy()/memmove() and so on, we use a jump table
to dispatch cases for short data lengths; and for long data lengths, we
split the destination into head part (first 8 bytes), tail part (last 8
bytes) and middle part. The head part and tail part may be at unaligned
addresses, while the middle part is always aligned (the middle part is
allowed to overlap the head/tail part). In this way, the first and last
8 bytes may be unaligned accesses, but we can make sure the data in the
middle is processed at an aligned destination address.

We have tested micro-bench[1] on a Loongson-3C5000 16-core machine (2.2GHz):

1. memset

| length | src offset | dst offset | speed before | speed after | % |
|--------|------------|------------|--------------|-------------|---------|
| 8 | 0 | 0 | 696.191 | 1518.785 | 118.16% |
| 8 | 0 | 1 | 696.325 | 1518.937 | 118.14% |
| 50 | 0 | 0 | 969.976 | 8053.902 | 730.32% |
| 50 | 0 | 1 | 970.034 | 8058.475 | 730.74% |
| 300 | 0 | 0 | 5876.612 | 16544.703 | 181.53% |
| 300 | 0 | 1 | 5030.849 | 16549.011 | 228.95% |
| 1200 | 0 | 0 | 11797.077 | 16752.137 | 42.00% |
| 1200 | 0 | 1 | 5687.141 | 16645.233 | 192.68% |
| 4000 | 0 | 0 | 15723.27 | 16761.557 | 6.60% |
| 4000 | 0 | 1 | 5906.114 | 16732.316 | 183.30% |
| 8000 | 0 | 0 | 16751.403 | 16770.002 | 0.11% |
| 8000 | 0 | 1 | 5995.449 | 16754.07 | 179.45% |

2. memcpy

| length | src offset | dst offset | speed before | speed after | % |
|--------|------------|------------|--------------|-------------|---------|
| 8 | 0 | 0 | 696.2 | 1670.605 | 139.96% |
| 8 | 0 | 1 | 696.325 | 1671.138 | 139.99% |
| 50 | 0 | 0 | 969.974 | 8724.999 | 799.51% |
| 50 | 0 | 1 | 970.032 | 8730.138 | 799.98% |
| 300 | 0 | 0 | 5564.662 | 16272.652 | 192.43% |
| 300 | 0 | 1 | 4670.436 | 14972.842 | 220.59% |
| 1200 | 0 | 0 | 10740.23 | 16751.728 | 55.97% |
| 1200 | 0 | 1 | 5027.741 | 14874.564 | 195.85% |
| 4000 | 0 | 0 | 15122.367 | 16737.642 | 10.68% |
| 4000 | 0 | 1 | 5536.918 | 14890.397 | 168.93% |
| 8000 | 0 | 0 | 16505.453 | 16553.543 | 0.29% |
| 8000 | 0 | 1 | 5821.619 | 14841.804 | 154.94% |

3. memmove

| length | src offset | dst offset | speed before | speed after | % |
|--------|------------|------------|--------------|-------------|---------|
| 8 | 0 | 0 | 982.693 | 1670.568 | 70.00% |
| 8 | 0 | 1 | 983.023 | 1671.174 | 70.00% |
| 50 | 0 | 0 | 1230.87 | 8727.625 | 609.06% |
| 50 | 0 | 1 | 1232.515 | 8730.138 | 608.32% |
| 300 | 0 | 0 | 6490.375 | 16296.993 | 151.09% |
| 300 | 0 | 1 | 4282.687 | 14972.842 | 249.61% |
| 1200 | 0 | 0 | 11742.755 | 16752.546 | 42.66% |
| 1200 | 0 | 1 | 5039.338 | 14872.951 | 195.14% |
| 4000 | 0 | 0 | 15467.786 | 16737.09 | 8.21% |
| 4000 | 0 | 1 | 5009.905 | 14890.542 | 197.22% |
| 8000 | 0 | 0 | 16489.664 | 16553.273 | 0.39% |
| 8000 | 0 | 1 | 5823.786 | 14858.646 | 155.14% |

* speed: MB/s
* length: byte

[1] https://github.com/heiher/mem-bench

Signed-off-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Mark some assembler symbols as non-kprobe-able

Some assembler symbols are not kprobe safe, such as handle_syscall (used
as syscall exception handler), *memset*/*memcpy*/*memmove* (may cause
recursive exceptions), they can not be instrumented, just blacklist them
for kprobing.

Here is a related problem and discussion:
Link: https://lore.kernel.org/lkml/20230114143859.7ccc45c1c5d9ce302113ab0a@kernel.org/

Tested-by: Jeff Xie <xiehuan09@gmail.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

LoongArch: Use alternative to optimize libraries

Use the alternative to optimize common libraries according whether CPU
has UAL (hardware unaligned access support) feature, including memset(),
memcopy(), memmove(), copy_user() and clear_user().

We have tested UnixBench on a Loongson-3A5000 quad-core machine (1.6GHz):

1, One copy, before patch:

System Benchmarks Index Values BASELINE RESULT INDEX
Dhrystone 2 using register variables 116700.0 9566582.0 819.8
Double-Precision Whetstone 55.0 2805.3 510.1
Execl Throughput 43.0 2120.0 493.0
File Copy 1024 bufsize 2000 maxblocks 3960.0 209833.0 529.9
File Copy 256 bufsize 500 maxblocks 1655.0 89400.0 540.2
File Copy 4096 bufsize 8000 maxblocks 5800.0 320036.0 551.8
Pipe Throughput 12440.0 340624.0 273.8
Pipe-based Context Switching 4000.0 109939.1 274.8
Process Creation 126.0 4728.7 375.3
Shell Scripts (1 concurrent) 42.4 2223.1 524.3
Shell Scripts (8 concurrent) 6.0 883.1 1471.9
System Call Overhead 15000.0 518639.1 345.8
========
System Benchmarks Index Score 500.2

2, One copy, after patch:

System Benchmarks Index Values BASELINE RESULT INDEX
Dhrystone 2 using register variables 116700.0 9567674.7 819.9
Double-Precision Whetstone 55.0 2805.5 510.1
Execl Throughput 43.0 2392.7 556.4
File Copy 1024 bufsize 2000 maxblocks 3960.0 417804.0 1055.1
File Copy 256 bufsize 500 maxblocks 1655.0 112909.5 682.2
File Copy 4096 bufsize 8000 maxblocks 5800.0 1255207.4 2164.2
Pipe Throughput 12440.0 555712.0 446.7
Pipe-based Context Switching 4000.0 99964.5 249.9
Process Creation 126.0 5192.5 412.1
Shell Scripts (1 concurrent) 42.4 2302.4 543.0
Shell Scripts (8 concurrent) 6.0 919.6 1532.6
System Call Overhead 15000.0 511159.3 340.8
========
System Benchmarks Index Score 640.1

3, Four copies, before patch:

System Benchmarks Index Values BASELINE RESULT INDEX
Dhrystone 2 using register variables 116700.0 38268610.5 3279.2
Double-Precision Whetstone 55.0 11222.2 2040.4
Execl Throughput 43.0 7892.0 1835.3
File Copy 1024 bufsize 2000 maxblocks 3960.0 235149.6 593.8
File Copy 256 bufsize 500 maxblocks 1655.0 74959.6 452.9
File Copy 4096 bufsize 8000 maxblocks 5800.0 545048.5 939.7
Pipe Throughput 12440.0 1337359.0 1075.0
Pipe-based Context Switching 4000.0 473663.9 1184.2
Process Creation 126.0 17491.2 1388.2
Shell Scripts (1 concurrent) 42.4 6865.7 1619.3
Shell Scripts (8 concurrent) 6.0 1015.9 1693.1
System Call Overhead 15000.0 1899535.2 1266.4
========
System Benchmarks Index Score 1278.3

4, Four copies, after patch:

System Benchmarks Index Values BASELINE RESULT INDEX
Dhrystone 2 using register variables 116700.0 38272815.5 3279.6
Double-Precision Whetstone 55.0 11222.8 2040.5
Execl Throughput 43.0 8839.2 2055.6
File Copy 1024 bufsize 2000 maxblocks 3960.0 313912.9 792.7
File Copy 256 bufsize 500 maxblocks 1655.0 80976.1 489.3
File Copy 4096 bufsize 8000 maxblocks 5800.0 1176594.3 2028.6
Pipe Throughput 12440.0 2100941.9 1688.9
Pipe-based Context Switching 4000.0 476696.4 1191.7
Process Creation 126.0 18394.7 1459.9
Shell Scripts (1 concurrent) 42.4 7172.2 1691.6
Shell Scripts (8 concurrent) 6.0 1058.3 1763.9
System Call Overhead 15000.0 1874714.7 1249.8
========
System Benchmarks Index Score 1488.8

Signed-off-by: Jun Yi <yijun@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>