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| author | Jiaxun Yang <jiaxun.yang@flygoat.com> | 2023-02-28 12:33:05 +0100 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2023-02-28 14:52:55 +0100 |
| commit | 7364d60c26618d7465602ac86717a5a325b342f3 (patch) | |
| tree | a9c39649accdc0021ab03698bc247f2970f8f3c9 /arch/mips/net | |
| parent | bpf, mips: Implement DADDI workarounds for JIT (diff) | |
| download | linux-7364d60c26618d7465602ac86717a5a325b342f3.tar.xz linux-7364d60c26618d7465602ac86717a5a325b342f3.zip | |
bpf, mips: Implement R4000 workarounds for JIT
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 according to workaround suggestion
in the document.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Link: https://lore.kernel.org/bpf/20230228113305.83751-3-jiaxun.yang@flygoat.com
Diffstat (limited to 'arch/mips/net')
| -rw-r--r-- | arch/mips/net/bpf_jit_comp64.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/mips/net/bpf_jit_comp64.c b/arch/mips/net/bpf_jit_comp64.c index 0e7c1bdcf914..fa7e9aa37f49 100644 --- a/arch/mips/net/bpf_jit_comp64.c +++ b/arch/mips/net/bpf_jit_comp64.c @@ -228,6 +228,9 @@ static void emit_alu_r64(struct jit_context *ctx, u8 dst, u8 src, u8 op) } else { emit(ctx, dmultu, dst, src); emit(ctx, mflo, dst); + /* Ensure multiplication is completed */ + if (IS_ENABLED(CONFIG_CPU_R4000_WORKAROUNDS)) + emit(ctx, mfhi, MIPS_R_ZERO); } break; /* dst = dst / src */ |