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authorPuranjay Mohan <puranjay@kernel.org>2024-05-05 20:16:33 +0000
committerAlexei Starovoitov <ast@kernel.org>2024-05-12 17:00:06 -0700
commit20a759df3bba35bf5c3ddec0c02ad69b603b584c (patch)
tree7006fd829bd640badfba46ab78baa7c03ff5f4d8 /arch/riscv
parent80c5a07ae673a740ef7ef0fe1ab588075a25ce8d (diff)
riscv, bpf: make some atomic operations fully ordered
The BPF atomic operations with the BPF_FETCH modifier along with BPF_XCHG and BPF_CMPXCHG are fully ordered but the RISC-V JIT implements all atomic operations except BPF_CMPXCHG with relaxed ordering. Section 8.1 of the "The RISC-V Instruction Set Manual Volume I: Unprivileged ISA" [1], titled, "Specifying Ordering of Atomic Instructions" says: | To provide more efficient support for release consistency [5], each | atomic instruction has two bits, aq and rl, used to specify additional | memory ordering constraints as viewed by other RISC-V harts. and | If only the aq bit is set, the atomic memory operation is treated as | an acquire access. | If only the rl bit is set, the atomic memory operation is treated as a | release access. | | If both the aq and rl bits are set, the atomic memory operation is | sequentially consistent. Fix this by setting both aq and rl bits as 1 for operations with BPF_FETCH and BPF_XCHG. [1] https://riscv.org/wp-content/uploads/2017/05/riscv-spec-v2.2.pdf Fixes: dd642ccb45ec ("riscv, bpf: Implement more atomic operations for RV64") Signed-off-by: Puranjay Mohan <puranjay@kernel.org> Reviewed-by: Pu Lehui <pulehui@huawei.com> Link: https://lore.kernel.org/r/20240505201633.123115-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/riscv')
-rw-r--r--arch/riscv/net/bpf_jit_comp64.c20
1 files changed, 10 insertions, 10 deletions
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index a46ec7fb4489..e51b291b5baa 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -504,33 +504,33 @@ static void emit_atomic(u8 rd, u8 rs, s16 off, s32 imm, bool is64,
break;
/* src_reg = atomic_fetch_<op>(dst_reg + off16, src_reg) */
case BPF_ADD | BPF_FETCH:
- emit(is64 ? rv_amoadd_d(rs, rs, rd, 0, 0) :
- rv_amoadd_w(rs, rs, rd, 0, 0), ctx);
+ emit(is64 ? rv_amoadd_d(rs, rs, rd, 1, 1) :
+ rv_amoadd_w(rs, rs, rd, 1, 1), ctx);
if (!is64)
emit_zextw(rs, rs, ctx);
break;
case BPF_AND | BPF_FETCH:
- emit(is64 ? rv_amoand_d(rs, rs, rd, 0, 0) :
- rv_amoand_w(rs, rs, rd, 0, 0), ctx);
+ emit(is64 ? rv_amoand_d(rs, rs, rd, 1, 1) :
+ rv_amoand_w(rs, rs, rd, 1, 1), ctx);
if (!is64)
emit_zextw(rs, rs, ctx);
break;
case BPF_OR | BPF_FETCH:
- emit(is64 ? rv_amoor_d(rs, rs, rd, 0, 0) :
- rv_amoor_w(rs, rs, rd, 0, 0), ctx);
+ emit(is64 ? rv_amoor_d(rs, rs, rd, 1, 1) :
+ rv_amoor_w(rs, rs, rd, 1, 1), ctx);
if (!is64)
emit_zextw(rs, rs, ctx);
break;
case BPF_XOR | BPF_FETCH:
- emit(is64 ? rv_amoxor_d(rs, rs, rd, 0, 0) :
- rv_amoxor_w(rs, rs, rd, 0, 0), ctx);
+ emit(is64 ? rv_amoxor_d(rs, rs, rd, 1, 1) :
+ rv_amoxor_w(rs, rs, rd, 1, 1), ctx);
if (!is64)
emit_zextw(rs, rs, ctx);
break;
/* src_reg = atomic_xchg(dst_reg + off16, src_reg); */
case BPF_XCHG:
- emit(is64 ? rv_amoswap_d(rs, rs, rd, 0, 0) :
- rv_amoswap_w(rs, rs, rd, 0, 0), ctx);
+ emit(is64 ? rv_amoswap_d(rs, rs, rd, 1, 1) :
+ rv_amoswap_w(rs, rs, rd, 1, 1), ctx);
if (!is64)
emit_zextw(rs, rs, ctx);
break;