From 78372709bf95c2ef5c886780efc268f7f052168a Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Tue, 7 Nov 2017 19:16:25 +0100 Subject: s390/bpf: take advantage of stack_depth tracking Make use of the "stack_depth" tracking feature introduced with commit 8726679a0fa31 ("bpf: teach verifier to track stack depth") for the s390 JIT, so that stack usage can be reduced. Signed-off-by: Michael Holzheu Signed-off-by: Heiko Carstens --- arch/s390/net/bpf_jit.h | 7 +++++-- arch/s390/net/bpf_jit_comp.c | 26 +++++++++++++------------- 2 files changed, 18 insertions(+), 15 deletions(-) (limited to 'arch/s390') diff --git a/arch/s390/net/bpf_jit.h b/arch/s390/net/bpf_jit.h index fda605dbc1b4..5057728b300e 100644 --- a/arch/s390/net/bpf_jit.h +++ b/arch/s390/net/bpf_jit.h @@ -52,10 +52,13 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[]; * * We get 160 bytes stack space from calling function, but only use * 12 * 8 byte for old backchain, r15..r6, and tail_call_cnt. + * + * The stack size used by the BPF program ("BPF stack" above) is passed + * via "aux->stack_depth". */ -#define STK_SPACE (MAX_BPF_STACK + 8 + 8 + 4 + 4 + 160) +#define STK_SPACE_ADD (8 + 8 + 4 + 4 + 160) #define STK_160_UNUSED (160 - 12 * 8) -#define STK_OFF (STK_SPACE - STK_160_UNUSED) +#define STK_OFF (STK_SPACE_ADD - 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 */ #define STK_OFF_SKBP 176 /* Offset of SKB pointer on stack */ diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 8ec88497a28d..6730652b1a75 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -319,12 +319,12 @@ static void save_regs(struct bpf_jit *jit, u32 rs, u32 re) /* * Restore registers from "rs" (register start) to "re" (register end) on stack */ -static void restore_regs(struct bpf_jit *jit, u32 rs, u32 re) +static void restore_regs(struct bpf_jit *jit, u32 rs, u32 re, u32 stack_depth) { u32 off = STK_OFF_R6 + (rs - 6) * 8; if (jit->seen & SEEN_STACK) - off += STK_OFF; + off += STK_OFF + stack_depth; if (rs == re) /* lg %rs,off(%r15) */ @@ -368,7 +368,7 @@ static int get_end(struct bpf_jit *jit, int start) * Save and restore clobbered registers (6-15) on stack. * We save/restore registers in chunks with gap >= 2 registers. */ -static void save_restore_regs(struct bpf_jit *jit, int op) +static void save_restore_regs(struct bpf_jit *jit, int op, u32 stack_depth) { int re = 6, rs; @@ -381,7 +381,7 @@ static void save_restore_regs(struct bpf_jit *jit, int op) if (op == REGS_SAVE) save_regs(jit, rs, re); else - restore_regs(jit, rs, re); + restore_regs(jit, rs, re, stack_depth); re++; } while (re <= 15); } @@ -413,7 +413,7 @@ static void emit_load_skb_data_hlen(struct bpf_jit *jit) * Save registers and create stack frame if necessary. * See stack frame layout desription in "bpf_jit.h"! */ -static void bpf_jit_prologue(struct bpf_jit *jit) +static void bpf_jit_prologue(struct bpf_jit *jit, u32 stack_depth) { if (jit->seen & SEEN_TAIL_CALL) { /* xc STK_OFF_TCCNT(4,%r15),STK_OFF_TCCNT(%r15) */ @@ -426,7 +426,7 @@ static void bpf_jit_prologue(struct bpf_jit *jit) /* Tail calls have to skip above initialization */ jit->tail_call_start = jit->prg; /* Save registers */ - save_restore_regs(jit, REGS_SAVE); + save_restore_regs(jit, REGS_SAVE, stack_depth); /* Setup literal pool */ if (jit->seen & SEEN_LITERAL) { /* basr %r13,0 */ @@ -441,7 +441,7 @@ static void bpf_jit_prologue(struct bpf_jit *jit) /* 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); + EMIT4_IMM(0xa70b0000, REG_15, -(STK_OFF + stack_depth)); if (jit->seen & SEEN_FUNC) /* stg %w1,152(%r15) (backchain) */ EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, @@ -458,7 +458,7 @@ static void bpf_jit_prologue(struct bpf_jit *jit) /* * Function epilogue */ -static void bpf_jit_epilogue(struct bpf_jit *jit) +static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth) { /* Return 0 */ if (jit->seen & SEEN_RET0) { @@ -470,7 +470,7 @@ static void bpf_jit_epilogue(struct bpf_jit *jit) /* Load exit code: lgr %r2,%b0 */ EMIT4(0xb9040000, REG_2, BPF_REG_0); /* Restore registers */ - save_restore_regs(jit, REGS_RESTORE); + save_restore_regs(jit, REGS_RESTORE, stack_depth); /* br %r14 */ _EMIT2(0x07fe); } @@ -1018,7 +1018,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i */ if (jit->seen & SEEN_STACK) - off = STK_OFF_TCCNT + STK_OFF; + off = STK_OFF_TCCNT + STK_OFF + fp->aux->stack_depth; else off = STK_OFF_TCCNT; /* lhi %w0,1 */ @@ -1046,7 +1046,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i /* * Restore registers before calling function */ - save_restore_regs(jit, REGS_RESTORE); + save_restore_regs(jit, REGS_RESTORE, fp->aux->stack_depth); /* * goto *(prog->bpf_func + tail_call_start); @@ -1272,7 +1272,7 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp) jit->lit = jit->lit_start; jit->prg = 0; - bpf_jit_prologue(jit); + bpf_jit_prologue(jit, fp->aux->stack_depth); for (i = 0; i < fp->len; i += insn_count) { insn_count = bpf_jit_insn(jit, fp, i); if (insn_count < 0) @@ -1280,7 +1280,7 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp) /* Next instruction address */ jit->addrs[i + insn_count] = jit->prg; } - bpf_jit_epilogue(jit); + bpf_jit_epilogue(jit, fp->aux->stack_depth); jit->lit_start = jit->prg; jit->size = jit->lit; -- cgit