LoongArch, bpf: Use 4 instructions for function address in JIT

Browse source

[ Upstream commit 64f50f6575 ]

This patch fixes the following issue of function calls in JIT, like:

  [   29.346981] multi-func JIT bug 105 != 103

The issus can be reproduced by running the "inline simple bpf_loop call"
verifier test.

This is because we are emiting 2-4 instructions for 64-bit immediate moves.
During the first pass of JIT, the placeholder address is zero, emiting two
instructions for it. In the extra pass, the function address is in XKVRANGE,
emiting four instructions for it. This change the instruction index in
JIT context. Let's always use 4 instructions for function address in JIT.
So that the instruction sequences don't change between the first pass and
the extra pass for function calls.

Fixes: 5dc615520c ("LoongArch: Add BPF JIT support")
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/bpf/20230214152633.2265699-1-hengqi.chen@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

This commit is contained in:

Hengqi Chen 2023-02-14 15:26:33 +00:00 • committed by Greg Kroah-Hartman

parent cecc68559c

commit 30651cff1e

2 changed files with 22 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

2

arch/loongarch/net/bpf_jit.c

View file

21

arch/loongarch/net/bpf_jit.h

View file