From bbac1c94880cb8c7e093718897f4822f3933dd3c Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Mon, 1 Jun 2015 22:48:34 -0700 Subject: s390/bpf: fix stack allocation On s390x we have to provide 160 bytes stack space before we can call the next function. From the 160 bytes that we got from the previous function we only use 11 * 8 bytes and have 160 - 11 * 8 bytes left. Currently for BPF we allocate additional 160 - 11 * 8 bytes for the next function. This is wrong because then the next function only gets: (160 - 11 * 8) + (160 - 11 * 8) = 2 * 72 = 144 bytes Fix this and allocate enough memory for the next function. Fixes: 054623105728 ("s390/bpf: Add s390x eBPF JIT compiler backend") Signed-off-by: Michael Holzheu Acked-by: Heiko Carstens Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- arch/s390/net/bpf_jit.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/s390/net/bpf_jit.h b/arch/s390/net/bpf_jit.h index ba8593a515ba..de156ba3bd71 100644 --- a/arch/s390/net/bpf_jit.h +++ b/arch/s390/net/bpf_jit.h @@ -48,7 +48,9 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[]; * We get 160 bytes stack space from calling function, but only use * 11 * 8 byte (old backchain + r15 - r6) for storing registers. */ -#define STK_OFF (MAX_BPF_STACK + 8 + 4 + 4 + (160 - 11 * 8)) +#define STK_SPACE (MAX_BPF_STACK + 8 + 4 + 4 + 160) +#define STK_160_UNUSED (160 - 11 * 8) +#define STK_OFF (STK_SPACE - STK_160_UNUSED) #define STK_OFF_TMP 160 /* Offset of tmp buffer on stack */ #define STK_OFF_HLEN 168 /* Offset of SKB header length on stack */ -- cgit v1.2.3 From 88aeca15d637c279171ba441730ef41e4c4ce0ed Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Mon, 1 Jun 2015 22:48:35 -0700 Subject: s390/bpf: fix bpf frame pointer setup Currently the bpf frame pointer is set to the old r15. This is wrong because of packed stack. Fix this and adjust the frame pointer to respect packed stack. This now generates a prolog like the following: 3ff8001c3fa: eb67f0480024 stmg %r6,%r7,72(%r15) 3ff8001c400: ebcff0780024 stmg %r12,%r15,120(%r15) 3ff8001c406: b904001f lgr %r1,%r15 <- load backchain 3ff8001c40a: 41d0f048 la %r13,72(%r15) <- load adjusted bfp 3ff8001c40e: a7fbfd98 aghi %r15,-616 3ff8001c412: e310f0980024 stg %r1,152(%r15) <- save backchain Fixes: 054623105728 ("s390/bpf: Add s390x eBPF JIT compiler backend") Signed-off-by: Michael Holzheu Acked-by: Heiko Carstens Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- arch/s390/net/bpf_jit_comp.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 20c146d1251a..55423d8be580 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -384,13 +384,16 @@ static void bpf_jit_prologue(struct bpf_jit *jit) } /* Setup stack and backchain */ if (jit->seen & SEEN_STACK) { - /* lgr %bfp,%r15 (BPF frame pointer) */ - EMIT4(0xb9040000, BPF_REG_FP, REG_15); + if (jit->seen & SEEN_FUNC) + /* lgr %w1,%r15 (backchain) */ + EMIT4(0xb9040000, REG_W1, REG_15); + /* la %bfp,STK_160_UNUSED(%r15) (BPF frame pointer) */ + EMIT4_DISP(0x41000000, BPF_REG_FP, REG_15, STK_160_UNUSED); /* aghi %r15,-STK_OFF */ EMIT4_IMM(0xa70b0000, REG_15, -STK_OFF); if (jit->seen & SEEN_FUNC) - /* stg %bfp,152(%r15) (backchain) */ - EMIT6_DISP_LH(0xe3000000, 0x0024, BPF_REG_FP, REG_0, + /* stg %w1,152(%r15) (backchain) */ + EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15, 152); } /* -- cgit v1.2.3