bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Björn Töpel" <bjorn.topel@gmail.com>
To: daniel@iogearbox.net, ast@kernel.org, netdev@vger.kernel.org
Cc: "Björn Töpel" <bjorn.topel@gmail.com>,
	linux-riscv@lists.infradead.org, bpf@vger.kernel.org
Subject: [PATCH bpf-next 1/8] riscv, bpf: fix broken BPF tail calls
Date: Mon,  9 Dec 2019 18:31:29 +0100	[thread overview]
Message-ID: <20191209173136.29615-2-bjorn.topel@gmail.com> (raw)
In-Reply-To: <20191209173136.29615-1-bjorn.topel@gmail.com>

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>
---
 arch/riscv/net/bpf_jit_comp.c | 13 +++++++++++--
 1 file 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;
-- 
2.20.1


  reply	other threads:[~2019-12-09 17:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-09 17:31 [PATCH bpf-next 0/8] riscv: BPF JIT fix, optimizations and far jumps support Björn Töpel
2019-12-09 17:31 ` Björn Töpel [this message]
2019-12-09 17:31 ` [PATCH bpf-next 2/8] riscv, bpf: add support for far branching Björn Töpel
2019-12-09 21:08   ` Luke Nelson
2019-12-09 21:27     ` Daniel Borkmann
2019-12-10  7:02       ` Luke Nelson
2019-12-10  5:32     ` Björn Töpel
2019-12-10  5:31   ` Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 3/8] riscv, bpf: add support for far jumps and exits Björn Töpel
2019-12-09 21:15   ` Luke Nelson
2019-12-09 17:31 ` [PATCH bpf-next 4/8] riscv, bpf: optimize BPF tail calls Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 5/8] riscv, bpf: provide RISC-V specific JIT image alloc/free Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 6/8] riscv, bpf: optimize calls Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 7/8] riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 8/8] riscv, perf: add arch specific perf_arch_bpf_user_pt_regs Björn Töpel

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191209173136.29615-2-bjorn.topel@gmail.com \
    --to=bjorn.topel@gmail.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=linux-riscv@lists.infradead.org \
    --cc=netdev@vger.kernel.org \
    --subject='Re: [PATCH bpf-next 1/8] riscv, bpf: fix broken BPF tail calls' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).