Re: [PATCH 2/2] MIPS: ebpf jit: Implement R4000 workarounds

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On 22/2/23 17:12, Jiaxun Yang wrote:
For R4000 erratas around multiplication and division instructions,
as our use of those instructions are always followed by mflo/mfhi
instructions, the only issue we need care is

"MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0" Errata 28:
"A double-word or a variable shift may give an incorrect result if
executed while an integer multiplication is in progress."

We just emit a mfhi $0 to ensure the operation is completed after
every multiplication instruction accorading to workaround suggestion

Typo "according"

in the document.

Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
---
  arch/mips/Kconfig              | 4 +---
  arch/mips/net/bpf_jit_comp32.c | 4 ++++
  arch/mips/net/bpf_jit_comp64.c | 3 +++
  3 files changed, 8 insertions(+), 3 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>




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