* [PATCH 2/2] MIPS: eBPF: Remove REG_32BIT_ZERO_EX
2019-02-15 20:14 [PATCH 1/2] MIPS: eBPF: Always return sign extended 32b values Paul Burton
@ 2019-02-15 20:14 ` Paul Burton
2019-02-19 20:48 ` [PATCH 1/2] MIPS: eBPF: Always return sign extended 32b values Paul Burton
1 sibling, 0 replies; 3+ messages in thread
From: Paul Burton @ 2019-02-15 20:14 UTC (permalink / raw)
To: linux-mips, Alexei Starovoitov, Daniel Borkmann,
Martin KaFai Lau, Song Liu, Yonghong Song, netdev
Cc: linux-kernel, Jiong Wang, Paul Burton
REG_32BIT_ZERO_EX and REG_64BIT are always handled in exactly the same
way, and reg_val_propagate_range() never actually sets any register to
type REG_32BIT_ZERO_EX.
Remove the redundant & unused REG_32BIT_ZERO_EX.
Signed-off-by: Paul Burton <paul.burton@mips.com>
---
arch/mips/net/ebpf_jit.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 715415fa2345..76e9bf88d3b9 100644
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c
@@ -79,8 +79,6 @@ enum reg_val_type {
REG_64BIT_32BIT,
/* 32-bit compatible, need truncation for 64-bit ops. */
REG_32BIT,
- /* 32-bit zero extended. */
- REG_32BIT_ZERO_EX,
/* 32-bit no sign/zero extension needed. */
REG_32BIT_POS
};
@@ -349,7 +347,7 @@ static int build_int_epilogue(struct jit_ctx *ctx, int dest_reg)
if (dest_reg == MIPS_R_RA) {
/* Don't let zero extended value escape. */
td = get_reg_val_type(ctx, prog->len, BPF_REG_0);
- if (td == REG_64BIT || td == REG_32BIT_ZERO_EX)
+ if (td == REG_64BIT)
emit_instr(ctx, sll, r0, r0, 0);
}
@@ -695,7 +693,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
if (dst < 0)
return dst;
td = get_reg_val_type(ctx, this_idx, insn->dst_reg);
- if (td == REG_64BIT || td == REG_32BIT_ZERO_EX) {
+ if (td == REG_64BIT) {
/* sign extend */
emit_instr(ctx, sll, dst, dst, 0);
}
@@ -710,7 +708,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
if (dst < 0)
return dst;
td = get_reg_val_type(ctx, this_idx, insn->dst_reg);
- if (td == REG_64BIT || td == REG_32BIT_ZERO_EX) {
+ if (td == REG_64BIT) {
/* sign extend */
emit_instr(ctx, sll, dst, dst, 0);
}
@@ -724,7 +722,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
if (dst < 0)
return dst;
td = get_reg_val_type(ctx, this_idx, insn->dst_reg);
- if (td == REG_64BIT || td == REG_32BIT_ZERO_EX)
+ if (td == REG_64BIT)
/* sign extend */
emit_instr(ctx, sll, dst, dst, 0);
if (insn->imm == 1) {
@@ -863,13 +861,13 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
if (src < 0 || dst < 0)
return -EINVAL;
td = get_reg_val_type(ctx, this_idx, insn->dst_reg);
- if (td == REG_64BIT || td == REG_32BIT_ZERO_EX) {
+ if (td == REG_64BIT) {
/* sign extend */
emit_instr(ctx, sll, dst, dst, 0);
}
did_move = false;
ts = get_reg_val_type(ctx, this_idx, insn->src_reg);
- if (ts == REG_64BIT || ts == REG_32BIT_ZERO_EX) {
+ if (ts == REG_64BIT) {
int tmp_reg = MIPS_R_AT;
if (bpf_op == BPF_MOV) {
@@ -1257,8 +1255,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
if (insn->imm == 64 && td == REG_32BIT)
emit_instr(ctx, dinsu, dst, MIPS_R_ZERO, 32, 32);
- if (insn->imm != 64 &&
- (td == REG_64BIT || td == REG_32BIT_ZERO_EX)) {
+ if (insn->imm != 64 && td == REG_64BIT) {
/* sign extend */
emit_instr(ctx, sll, dst, dst, 0);
}
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 1/2] MIPS: eBPF: Always return sign extended 32b values
2019-02-15 20:14 [PATCH 1/2] MIPS: eBPF: Always return sign extended 32b values Paul Burton
2019-02-15 20:14 ` [PATCH 2/2] MIPS: eBPF: Remove REG_32BIT_ZERO_EX Paul Burton
@ 2019-02-19 20:48 ` Paul Burton
1 sibling, 0 replies; 3+ messages in thread
From: Paul Burton @ 2019-02-19 20:48 UTC (permalink / raw)
To: Paul Burton
Cc: linux-mips, Alexei Starovoitov, Daniel Borkmann,
Martin KaFai Lau, Song Liu, Yonghong Song, netdev, linux-kernel,
Jiong Wang, Paul Burton, stable, linux-mips
Hello,
Paul Burton wrote:
> The function prototype used to call JITed eBPF code (ie. the type of the
> struct bpf_prog bpf_func field) returns an unsigned int. The MIPS n64
> ABI that MIPS64 kernels target defines that 32 bit integers should
> always be sign extended when passed in registers as either arguments or
> return values.
>
> This means that when returning any value which may not already be sign
> extended (ie. of type REG_64BIT or REG_32BIT_ZERO_EX) we need to perform
> that sign extension in order to comply with the n64 ABI. Without this we
> see strange looking test failures from test_bpf.ko, such as:
>
> test_bpf: #65 ALU64_MOV_X:
> dst = 4294967295 jited:1 ret -1 != -1 FAIL (1 times)
>
> Although the return value printed matches the expected value, this is
> only because printf is only examining the least significant 32 bits of
> the 64 bit register value we returned. The register holding the expected
> value is sign extended whilst the v0 register was set to a zero extended
> value by our JITed code, so when compared by a conditional branch
> instruction the values are not equal.
>
> We already handle this when the return value register is of type
> REG_32BIT_ZERO_EX, so simply extend this to also cover REG_64BIT.
>
> Signed-off-by: Paul Burton <paul.burton@mips.com>
> Fixes: b6bd53f9c4e8 ("MIPS: Add missing file for eBPF JIT.")
> Cc: stable@vger.kernel.org # v4.13+
Series applied to mips-next.
Thanks,
Paul
[ This message was auto-generated; if you believe anything is incorrect
then please email paul.burton@mips.com to report it. ]
^ permalink raw reply [flat|nested] 3+ messages in thread