MBLY__ */ - -/* - * Stackframe layout (packed stack): - * - * ^ high - * +---------------+ | - * | old backchain | | - * +---------------+ | - * | r15 - r6 | | - * +---------------+ | - * | 4 byte align | | - * | tail_call_cnt | | - * BFP -> +===============+ | - * | | | - * | BPF stack | | - * | | | - * R15+160 -> +---------------+ | - * | new backchain | | - * R15+152 -> +---------------+ | - * | + 152 byte SA | | - * R15 -> +---------------+ + low - * - * 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_ADD (160) -#define STK_160_UNUSED (160 - 12 * 8) -#define STK_OFF (STK_SPACE_ADD - STK_160_UNUSED) - -#define STK_OFF_R6 (160 - 11 * 8) /* Offset of r6 on stack */ -#define STK_OFF_TCCNT (160 - 12 * 8) /* Offset of tail_call_cnt on stack */ - -#endif /* __ARCH_S390_NET_BPF_JIT_H */ diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 0137fb579fdb9..cfcf2ee960944 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -31,7 +31,6 @@ #include #include #include -#include "bpf_jit.h" struct bpf_jit { u32 seen; /* Flags to remember seen eBPF instructions */ @@ -53,7 +52,7 @@ struct bpf_jit { int excnt; /* Number of exception table entries */ int prologue_plt_ret; /* Return address for prologue hotpatch PLT */ int prologue_plt; /* Start of prologue hotpatch PLT */ - u32 frame_off; /* Offset of frame from %r15 */ + u32 frame_off; /* Offset of struct bpf_prog from %r15 */ }; #define SEEN_MEM BIT(0) /* use mem[] for temporary storage */ @@ -399,12 +398,26 @@ static void jit_fill_hole(void *area, unsigned int size) memset(area, 0, size); } +/* + * Caller-allocated part of the frame. + * Thanks to packed stack, its otherwise unused initial part can be used for + * the BPF stack and for the next frame. + */ +struct prog_frame { + u64 unused[8]; + /* BPF stack starts here and grows towards 0 */ + u32 tail_call_cnt; + u32 pad; + u64 r6[10]; /* r6 - r15 */ + u64 backchain; +} __packed; + /* * Save registers from "rs" (register start) to "re" (register end) on stack */ static void save_regs(struct bpf_jit *jit, u32 rs, u32 re) { - u32 off = STK_OFF_R6 + (rs - 6) * 8; + u32 off = offsetof(struct prog_frame, r6) + (rs - 6) * 8; if (rs == re) /* stg %rs,off(%r15) */ @@ -419,7 +432,7 @@ static void save_regs(struct bpf_jit *jit, u32 rs, u32 re) */ static void restore_regs(struct bpf_jit *jit, u32 rs, u32 re) { - u32 off = jit->frame_off + STK_OFF_R6 + (rs - 6) * 8; + u32 off = jit->frame_off + offsetof(struct prog_frame, r6) + (rs - 6) * 8; if (rs == re) /* lg %rs,off(%r15) */ @@ -551,10 +564,12 @@ static void bpf_jit_plt(struct bpf_plt *plt, void *ret, void *target) * Emit function prologue * * Save registers and create stack frame if necessary. - * See stack frame layout description in "bpf_jit.h"! + * Stack frame layout is described by struct prog_frame. */ static void bpf_jit_prologue(struct bpf_jit *jit, struct bpf_prog *fp) { + BUILD_BUG_ON(sizeof(struct prog_frame) != STACK_FRAME_OVERHEAD); + /* No-op for hotpatching */ /* brcl 0,prologue_plt */ EMIT6_PCREL_RILC(0xc0040000, 0, jit->prologue_plt); @@ -562,8 +577,9 @@ static void bpf_jit_prologue(struct bpf_jit *jit, struct bpf_prog *fp) if (fp->aux->func_idx == 0) { /* Initialize the tail call counter in the main program. */ - /* xc STK_OFF_TCCNT(4,%r15),STK_OFF_TCCNT(%r15) */ - _EMIT6(0xd703f000 | STK_OFF_TCCNT, 0xf000 | STK_OFF_TCCNT); + /* xc tail_call_cnt(4,%r15),tail_call_cnt(%r15) */ + _EMIT6(0xd703f000 | offsetof(struct prog_frame, tail_call_cnt), + 0xf000 | offsetof(struct prog_frame, tail_call_cnt)); } else { /* * Skip the tail call counter initialization in subprograms. @@ -593,13 +609,15 @@ static void bpf_jit_prologue(struct bpf_jit *jit, struct bpf_prog *fp) if (is_first_pass(jit) || (jit->seen & SEEN_STACK)) { /* 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); + /* la %bfp,unused_end(%r15) (BPF frame pointer) */ + EMIT4_DISP(0x41000000, BPF_REG_FP, REG_15, + offsetofend(struct prog_frame, unused)); /* aghi %r15,-frame_off */ EMIT4_IMM(0xa70b0000, REG_15, -jit->frame_off); - /* stg %w1,152(%r15) (backchain) */ + /* stg %w1,backchain(%r15) */ EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, - REG_15, 152); + REG_15, + offsetof(struct prog_frame, backchain)); } } @@ -1429,9 +1447,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, * Note 2: We assume that the verifier does not let us call the * main program, which clears the tail call counter on entry. */ - /* mvc STK_OFF_TCCNT(4,%r15),frame_off+STK_OFF_TCCNT(%r15) */ - _EMIT6(0xd203f000 | STK_OFF_TCCNT, - 0xf000 | (jit->frame_off + STK_OFF_TCCNT)); + /* mvc tail_call_cnt(4,%r15),frame_off+tail_call_cnt(%r15) */ + _EMIT6(0xd203f000 | offsetof(struct prog_frame, tail_call_cnt), + 0xf000 | (jit->frame_off + + offsetof(struct prog_frame, tail_call_cnt))); /* Sign-extend the kfunc arguments. */ if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { @@ -1482,7 +1501,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, * goto out; */ - off = jit->frame_off + STK_OFF_TCCNT; + off = jit->frame_off + + offsetof(struct prog_frame, tail_call_cnt); /* lhi %w0,1 */ EMIT4_IMM(0xa7080000, REG_W0, 1); /* laal %w1,%w0,off(%r15) */ @@ -1824,7 +1844,9 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp, jit->prg = 0; jit->excnt = 0; if (is_first_pass(jit) || (jit->seen & SEEN_STACK)) - jit->frame_off = STK_OFF + round_up(fp->aux->stack_depth, 8); + jit->frame_off = sizeof(struct prog_frame) - + offsetofend(struct prog_frame, unused) + + round_up(fp->aux->stack_depth, 8); else jit->frame_off = 0; @@ -2281,9 +2303,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, /* stg %r1,backchain_off(%r15) */ EMIT6_DISP_LH(0xe3000000, 0x0024, REG_1, REG_0, REG_15, tjit->backchain_off); - /* mvc tccnt_off(4,%r15),stack_size+STK_OFF_TCCNT(%r15) */ + /* mvc tccnt_off(4,%r15),stack_size+tail_call_cnt(%r15) */ _EMIT6(0xd203f000 | tjit->tccnt_off, - 0xf000 | (tjit->stack_size + STK_OFF_TCCNT)); + 0xf000 | (tjit->stack_size + + offsetof(struct prog_frame, tail_call_cnt))); /* stmg %r2,%rN,fwd_reg_args_off(%r15) */ if (nr_reg_args) EMIT6_DISP_LH(0xeb000000, 0x0024, REG_2, @@ -2420,8 +2443,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, (nr_stack_args * sizeof(u64) - 1) << 16 | tjit->stack_args_off, 0xf000 | tjit->orig_stack_args_off); - /* mvc STK_OFF_TCCNT(4,%r15),tccnt_off(%r15) */ - _EMIT6(0xd203f000 | STK_OFF_TCCNT, 0xf000 | tjit->tccnt_off); + /* mvc tail_call_cnt(4,%r15),tccnt_off(%r15) */ + _EMIT6(0xd203f000 | offsetof(struct prog_frame, tail_call_cnt), + 0xf000 | tjit->tccnt_off); /* lgr %r1,%r8 */ EMIT4(0xb9040000, REG_1, REG_8); /* %r1() */ @@ -2478,8 +2502,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, if (flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET)) EMIT6_DISP_LH(0xe3000000, 0x0004, REG_2, REG_0, REG_15, tjit->retval_off); - /* mvc stack_size+STK_OFF_TCCNT(4,%r15),tccnt_off(%r15) */ - _EMIT6(0xd203f000 | (tjit->stack_size + STK_OFF_TCCNT), + /* mvc stack_size+tail_call_cnt(4,%r15),tccnt_off(%r15) */ + _EMIT6(0xd203f000 | (tjit->stack_size + + offsetof(struct prog_frame, tail_call_cnt)), 0xf000 | tjit->tccnt_off); /* aghi %r15,stack_size */ EMIT4_IMM(0xa70b0000, REG_15, tjit->stack_size); -- 2.51.0[PATCH 6.6.y 3/5] s390/bpf: Describe the frame using a struct instead of constantsIlya Leoshkevich undefinedstable@vger.kernel.org undefined undefined¥ ƒ£