Pu Lehui 443574b033 riscv, bpf: Fix kfunc parameters incompatibility between bpf and riscv abi ... We encountered a failing case when running selftest in no_alu32 mode: The failure case is `kfunc_call/kfunc_call_test4` and its source code is like bellow: ``` long bpf_kfunc_call_test4(signed char a, short b, int c, long d) __ksym; int kfunc_call_test4(struct __sk_buff *skb) { ... tmp = bpf_kfunc_call_test4(-3, -30, -200, -1000); ... } ``` And its corresponding asm code is: ``` 0: r1 = -3 1: r2 = -30 2: r3 = 0xffffff38 # opcode: 18 03 00 00 38 ff ff ff 00 00 00 00 00 00 00 00 4: r4 = -1000 5: call bpf_kfunc_call_test4 ``` insn 2 is parsed to ld_imm64 insn to emit 0x00000000ffffff38 imm, and converted to int type and then send to bpf_kfunc_call_test4. But since it is zero-extended in the bpf calling convention, riscv jit will directly treat it as an unsigned 32-bit int value, and then fails with the message "actual 4294966063 != expected -1234". The reason is the incompatibility between bpf and riscv abi, that is, bpf will do zero-extension on uint, but riscv64 requires sign-extension on int or uint. We can solve this problem by sign extending the 32-bit parameters in kfunc. The issue is related to [0], and thanks to Yonghong and Alexei. Link: https://github.com/llvm/llvm-project/pull/84874 [0] Fixes: d40c3847b4 ("riscv, bpf: Add kfunc support for RV64") Signed-off-by: Pu Lehui <pulehui@huawei.com> Tested-by: Puranjay Mohan <puranjay12@gmail.com> Reviewed-by: Puranjay Mohan <puranjay12@gmail.com> Link: https://lore.kernel.org/r/20240324103306.2202954-1-pulehui@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>		2024-03-25 11:39:31 -07:00
..
bpf_jit.h	bpf, riscv64/cfi: Support kCFI + BPF on riscv64	2024-03-06 15:18:16 -08:00
bpf_jit_comp32.c	bpf, riscv64/cfi: Support kCFI + BPF on riscv64	2024-03-06 15:18:16 -08:00
bpf_jit_comp64.c	riscv, bpf: Fix kfunc parameters incompatibility between bpf and riscv abi	2024-03-25 11:39:31 -07:00
bpf_jit_core.c	bpf, riscv64/cfi: Support kCFI + BPF on riscv64	2024-03-06 15:18:16 -08:00
Makefile	riscv, bpf: Add RV32G eBPF JIT	2020-03-05 16:13:47 +01:00