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authorBjörn Töpel <bjorn.topel@gmail.com>2019-12-16 10:13:35 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2019-12-19 16:03:30 +0100
commitf1003b787c00fbaa4b11619c6b23a885bfce8f07 (patch)
treeb64650e3842ab2900795dde3cd95ac6c487c0c63 /arch/riscv/net
parenta352a82496d17f210a88b4fe2de7904afdb92003 (diff)
riscv, bpf: Fix broken BPF tail calls
The BPF JIT incorrectly clobbered the a0 register, and did not flag usage of s5 register when BPF stack was being used. Fixes: 2353ecc6f91f ("bpf, riscv: add BPF JIT for RV64G") Signed-off-by: Björn Töpel <bjorn.topel@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20191216091343.23260-2-bjorn.topel@gmail.com
Diffstat (limited to 'arch/riscv/net')
-rw-r--r--arch/riscv/net/bpf_jit_comp.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c
index 5451ef3845f2..1606ebd49666 100644
--- a/arch/riscv/net/bpf_jit_comp.c
+++ b/arch/riscv/net/bpf_jit_comp.c
@@ -120,6 +120,11 @@ static bool seen_reg(int reg, struct rv_jit_context *ctx)
return false;
}
+static void mark_fp(struct rv_jit_context *ctx)
+{
+ __set_bit(RV_CTX_F_SEEN_S5, &ctx->flags);
+}
+
static void mark_call(struct rv_jit_context *ctx)
{
__set_bit(RV_CTX_F_SEEN_CALL, &ctx->flags);
@@ -596,7 +601,8 @@ static void __build_epilogue(u8 reg, struct rv_jit_context *ctx)
emit(rv_addi(RV_REG_SP, RV_REG_SP, stack_adjust), ctx);
/* Set return value. */
- emit(rv_addi(RV_REG_A0, RV_REG_A5, 0), ctx);
+ if (reg == RV_REG_RA)
+ emit(rv_addi(RV_REG_A0, RV_REG_A5, 0), ctx);
emit(rv_jalr(RV_REG_ZERO, reg, 0), ctx);
}
@@ -1426,6 +1432,10 @@ static void build_prologue(struct rv_jit_context *ctx)
{
int stack_adjust = 0, store_offset, bpf_stack_adjust;
+ bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
+ if (bpf_stack_adjust)
+ mark_fp(ctx);
+
if (seen_reg(RV_REG_RA, ctx))
stack_adjust += 8;
stack_adjust += 8; /* RV_REG_FP */
@@ -1443,7 +1453,6 @@ static void build_prologue(struct rv_jit_context *ctx)
stack_adjust += 8;
stack_adjust = round_up(stack_adjust, 16);
- bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
stack_adjust += bpf_stack_adjust;
store_offset = stack_adjust - 8;