summaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorPu Lehui <pulehui@huawei.com>2024-01-15 13:12:32 +0000
committerDaniel Borkmann <daniel@iogearbox.net>2024-01-29 16:25:33 +0100
commit361db44c3c59cde05e9926647f16255e274a37f4 (patch)
tree5a95a54d3a7fbc93b9d4dbf3205b4f854f562ace /arch
parent914c7a5ff18a225f7df254ae3433574f3d47b711 (diff)
riscv, bpf: Simplify sext and zext logics in branch instructions
There are many extension helpers in the current branch instructions, and the implementation is a bit complicated. We simplify this logic through two simple extension helpers with alternate register. Signed-off-by: Pu Lehui <pulehui@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Björn Töpel <bjorn@rivosinc.com> Acked-by: Björn Töpel <bjorn@kernel.org> Link: https://lore.kernel.org/bpf/20240115131235.2914289-4-pulehui@huaweicloud.com
Diffstat (limited to 'arch')
-rw-r--r--arch/riscv/net/bpf_jit_comp64.c79
1 files changed, 31 insertions, 48 deletions
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index d3d764ed32a2..0a26842535ea 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -141,6 +141,19 @@ static bool in_auipc_jalr_range(s64 val)
val < ((1L << 31) - (1L << 11));
}
+/* Modify rd pointer to alternate reg to avoid corrupting original reg */
+static void emit_sextw_alt(u8 *rd, u8 ra, struct rv_jit_context *ctx)
+{
+ emit_sextw(ra, *rd, ctx);
+ *rd = ra;
+}
+
+static void emit_zextw_alt(u8 *rd, u8 ra, struct rv_jit_context *ctx)
+{
+ emit_zextw(ra, *rd, ctx);
+ *rd = ra;
+}
+
/* Emit fixed-length instructions for address */
static int emit_addr(u8 rd, u64 addr, bool extra_pass, struct rv_jit_context *ctx)
{
@@ -399,38 +412,6 @@ static void init_regs(u8 *rd, u8 *rs, const struct bpf_insn *insn,
*rs = bpf_to_rv_reg(insn->src_reg, ctx);
}
-static void emit_zext_32_rd_rs(u8 *rd, u8 *rs, struct rv_jit_context *ctx)
-{
- emit_mv(RV_REG_T2, *rd, ctx);
- emit_zextw(RV_REG_T2, RV_REG_T2, ctx);
- emit_mv(RV_REG_T1, *rs, ctx);
- emit_zextw(RV_REG_T1, RV_REG_T1, ctx);
- *rd = RV_REG_T2;
- *rs = RV_REG_T1;
-}
-
-static void emit_sext_32_rd_rs(u8 *rd, u8 *rs, struct rv_jit_context *ctx)
-{
- emit_sextw(RV_REG_T2, *rd, ctx);
- emit_sextw(RV_REG_T1, *rs, ctx);
- *rd = RV_REG_T2;
- *rs = RV_REG_T1;
-}
-
-static void emit_zext_32_rd_t1(u8 *rd, struct rv_jit_context *ctx)
-{
- emit_mv(RV_REG_T2, *rd, ctx);
- emit_zextw(RV_REG_T2, RV_REG_T2, ctx);
- emit_zextw(RV_REG_T1, RV_REG_T2, ctx);
- *rd = RV_REG_T2;
-}
-
-static void emit_sext_32_rd(u8 *rd, struct rv_jit_context *ctx)
-{
- emit_sextw(RV_REG_T2, *rd, ctx);
- *rd = RV_REG_T2;
-}
-
static int emit_jump_and_link(u8 rd, s64 rvoff, bool fixed_addr,
struct rv_jit_context *ctx)
{
@@ -1419,10 +1400,13 @@ out_be:
rvoff = rv_offset(i, off, ctx);
if (!is64) {
s = ctx->ninsns;
- if (is_signed_bpf_cond(BPF_OP(code)))
- emit_sext_32_rd_rs(&rd, &rs, ctx);
- else
- emit_zext_32_rd_rs(&rd, &rs, ctx);
+ if (is_signed_bpf_cond(BPF_OP(code))) {
+ emit_sextw_alt(&rs, RV_REG_T1, ctx);
+ emit_sextw_alt(&rd, RV_REG_T2, ctx);
+ } else {
+ emit_zextw_alt(&rs, RV_REG_T1, ctx);
+ emit_zextw_alt(&rd, RV_REG_T2, ctx);
+ }
e = ctx->ninsns;
/* Adjust for extra insns */
@@ -1433,8 +1417,7 @@ out_be:
/* Adjust for and */
rvoff -= 4;
emit_and(RV_REG_T1, rd, rs, ctx);
- emit_branch(BPF_JNE, RV_REG_T1, RV_REG_ZERO, rvoff,
- ctx);
+ emit_branch(BPF_JNE, RV_REG_T1, RV_REG_ZERO, rvoff, ctx);
} else {
emit_branch(BPF_OP(code), rd, rs, rvoff, ctx);
}
@@ -1463,18 +1446,18 @@ out_be:
case BPF_JMP32 | BPF_JSLE | BPF_K:
rvoff = rv_offset(i, off, ctx);
s = ctx->ninsns;
- if (imm) {
+ if (imm)
emit_imm(RV_REG_T1, imm, ctx);
- rs = RV_REG_T1;
- } else {
- /* If imm is 0, simply use zero register. */
- rs = RV_REG_ZERO;
- }
+ rs = imm ? RV_REG_T1 : RV_REG_ZERO;
if (!is64) {
- if (is_signed_bpf_cond(BPF_OP(code)))
- emit_sext_32_rd(&rd, ctx);
- else
- emit_zext_32_rd_t1(&rd, ctx);
+ if (is_signed_bpf_cond(BPF_OP(code))) {
+ emit_sextw_alt(&rd, RV_REG_T2, ctx);
+ /* rs has been sign extended */
+ } else {
+ emit_zextw_alt(&rd, RV_REG_T2, ctx);
+ if (imm)
+ emit_zextw(rs, rs, ctx);
+ }
}
e = ctx->ninsns;