From: Björn Töpel Date: Mon, 16 Dec 2019 09:13:35 +0000 (+0100) Subject: riscv, bpf: Fix broken BPF tail calls X-Git-Tag: v5.5.3~212 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=664c5ddf637b6d9f7f8e0430026ae2acff049ab9;p=users%2Fdwmw2%2Flinux.git riscv, bpf: Fix broken BPF tail calls commit f1003b787c00fbaa4b11619c6b23a885bfce8f07 upstream. 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 Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20191216091343.23260-2-bjorn.topel@gmail.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c index 7fbf56aab6610..e2279fed8f564 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;