[ Upstream commit c0e8246 ]

memset() description in ISO/IEC 9899:1999 (and elsewhere) says:

	The memset function copies the value of c (converted to an
	unsigned char) into each of the first n characters of the
	object pointed to by s.

The kernel's arm32 memset does not cast c to unsigned char. This results
in the following code to produce erroneous output:

	char a[128];
	memset(a, -128, sizeof(a));

This is because gcc will generally emit the following code before
it calls memset() :

	mov   r0, r7
	mvn   r1, grate-driver#127        ; 0x7f
	bl    00000000 <memset>

r1 ends up with 0xffffff80 before being used by memset() and the
'a' array will have -128 once in every four bytes while the other
bytes will be set incorrectly to -1 like this (printing the first
8 bytes) :

	test_module: -128 -1 -1 -1
	test_module: -1 -1 -1 -128

The change here is to 'and' r1 with 255 before it is used.

Fixes: 1da177e ("Linux-2.6.12-rc2")
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kursad Oney <kursad.oney@broadcom.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Like commit 1cf3bfc ("bpf: Support 64-bit pointers to kfuncs")
for s390x, add support for 64-bit pointers to kfuncs for LoongArch.
Since the infrastructure is already implemented in BPF core, the only
thing need to be done is to override bpf_jit_supports_far_kfunc_call().

Before this change, several test_verifier tests failed:

  # ./test_verifier | grep # | grep FAIL
  grate-driver#119/p calls: invalid kfunc call: ptr_to_mem to struct with non-scalar FAIL
  grate-driver#120/p calls: invalid kfunc call: ptr_to_mem to struct with nesting depth > 4 FAIL
  grate-driver#121/p calls: invalid kfunc call: ptr_to_mem to struct with FAM FAIL
  grate-driver#122/p calls: invalid kfunc call: reg->type != PTR_TO_CTX FAIL
  grate-driver#123/p calls: invalid kfunc call: void * not allowed in func proto without mem size arg FAIL
  grate-driver#124/p calls: trigger reg2btf_ids[reg->type] for reg->type > __BPF_REG_TYPE_MAX FAIL
  grate-driver#125/p calls: invalid kfunc call: reg->off must be zero when passed to release kfunc FAIL
  grate-driver#126/p calls: invalid kfunc call: don't match first member type when passed to release kfunc FAIL
  grate-driver#127/p calls: invalid kfunc call: PTR_TO_BTF_ID with negative offset FAIL
  grate-driver#128/p calls: invalid kfunc call: PTR_TO_BTF_ID with variable offset FAIL
  grate-driver#129/p calls: invalid kfunc call: referenced arg needs refcounted PTR_TO_BTF_ID FAIL
  grate-driver#130/p calls: valid kfunc call: referenced arg needs refcounted PTR_TO_BTF_ID FAIL
  #486/p map_kptr: ref: reference state created and released on xchg FAIL

This is because the kfuncs in the loaded module are far away from
__bpf_call_base:

  ffff800002009440 t bpf_kfunc_call_test_fail1    [bpf_testmod]
  9000000002e128d8 T __bpf_call_base

The offset relative to __bpf_call_base does NOT fit in s32, which breaks
the assumption in BPF core. Enable bpf_jit_supports_far_kfunc_call() lifts
this limit.

Note that to reproduce the above result, tools/testing/selftests/bpf/config
should be applied, and run the test with JIT enabled, unpriv BPF enabled.

With this change, the test_verifier tests now all passed:

  # ./test_verifier
  ...
  Summary: 777 PASSED, 0 SKIPPED, 0 FAILED

Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>