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v6.3-rc7
linux/arch/loongarch
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George Guo a6f6a95f25 LoongArch, bpf: Fix jit to skip speculation barrier opcode 
Just skip the opcode(BPF_ST | BPF_NOSPEC) in the BPF JIT instead of
failing to JIT the entire program, given LoongArch currently has no
couterpart of a speculation barrier instruction. To verify the issue,
use the ltp testcase as shown below.

Also, Wang says:

  I can confirm there's currently no speculation barrier equivalent
  on LonogArch. (Loongson says there are builtin mitigations for
  Spectre-V1 and V2 on their chips, and AFAIK efforts to port the
  exploits to mips/LoongArch have all failed a few years ago.)

Without this patch:

  $ ./bpf_prog02
  [...]
  bpf_common.c:123: TBROK: Failed verification: ??? (524)
  [...]
  Summary:
  passed   0
  failed   0
  broken   1
  skipped  0
  warnings 0

With this patch:

  $ ./bpf_prog02
  [...]
  Summary:
  passed   0
  failed   0
  broken   0
  skipped  0
  warnings 0

Fixes: 5dc615520c ("LoongArch: Add BPF JIT support")
Signed-off-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: WANG Xuerui <git@xen0n.name>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/bpf/20230328071335.2664966-1-guodongtai@kylinos.cn
2023-03-28 10:34:52 +02:00
..
boot
configs LoongArch: kdump: Add single kernel image implementation 2023-02-25 22:12:17 +08:00
include LoongArch changes for v6.3 2023-03-01 09:27:00 -08:00
kernel LoongArch changes for v6.3 2023-03-01 09:27:00 -08:00
lib LoongArch: Mark some assembler symbols as non-kprobe-able 2023-02-25 22:12:17 +08:00
mm LoongArch: Add kprobes support 2023-02-25 22:12:17 +08:00
net LoongArch, bpf: Fix jit to skip speculation barrier opcode 2023-03-28 10:34:52 +02:00
pci LoongArch: Add FDT booting support from efi system table 2022-12-14 08:41:53 +08:00
power LoongArch: Add JUMP_VIRT_ADDR macro implementation to avoid using la.abs 2023-02-25 22:12:16 +08:00
vdso
Kbuild
Kconfig LoongArch: Add kprobes on ftrace support 2023-02-25 22:12:17 +08:00
Kconfig.debug
Makefile LoongArch: kdump: Add single kernel image implementation 2023-02-25 22:12:17 +08:00