Commit 9a048587 authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Daniel Borkmann
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s390/bpf: Get rid of get_probe_mem_regno() 



Commit 7fc8c362 ("s390/bpf: encode register within extable entry")
introduced explicit passing of the number of the register to be cleared
to ex_handler_bpf(), which replaced deducing it from the respective
native load instruction using get_probe_mem_regno().

Replace the second and last usage in the same manner, and remove this
function.

Signed-off-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240701234304.14336-4-iii@linux.ibm.com
parent d0736d8c

arch/s390/net/bpf_jit_comp.c

+7 −26
Original line number Diff line number Diff line
@@ -667,25 +667,6 @@ static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth) 
	jit->prg += sizeof(struct bpf_plt);

}



static int get_probe_mem_regno(const u8 *insn)

{

	/*

	 * insn must point to llgc, llgh, llgf, lg, lgb, lgh or lgf, which have

	 * destination register at the same position.

	 */

	if (insn[0] != 0xe3) /* common prefix */

		return -1;

	if (insn[5] != 0x90 && /* llgc */

	    insn[5] != 0x91 && /* llgh */

	    insn[5] != 0x16 && /* llgf */

	    insn[5] != 0x04 && /* lg */

	    insn[5] != 0x77 && /* lgb */

	    insn[5] != 0x15 && /* lgh */

	    insn[5] != 0x14) /* lgf */

		return -1;

	return insn[1] >> 4;

}



bool ex_handler_bpf(const struct exception_table_entry *x, struct pt_regs *regs)

{

	regs->psw.addr = extable_fixup(x);
@@ -699,12 +680,14 @@ bool ex_handler_bpf(const struct exception_table_entry *x, struct pt_regs *regs) 
struct bpf_jit_probe {

	int prg;	/* JITed instruction offset */

	int nop_prg;	/* JITed nop offset */

	int reg;	/* Register to clear on exception */

};



static void bpf_jit_probe_init(struct bpf_jit_probe *probe)

{

	probe->prg = -1;

	probe->nop_prg = -1;

	probe->reg = -1;

}



/*
@@ -725,7 +708,7 @@ static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp, 
			     struct bpf_jit_probe *probe)

{

	struct exception_table_entry *ex;

	int i, prg, reg;

	int i, prg;

	s64 delta;

	u8 *insn;
@@ -734,10 +717,6 @@ static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp, 
		/* Do nothing during early JIT passes. */

		return 0;

	insn = jit->prg_buf + probe->prg;

	reg = get_probe_mem_regno(insn);

	if (WARN_ON_ONCE(reg < 0))

		/* JIT bug - unexpected probe instruction. */

		return -1;

	if (WARN_ON_ONCE(probe->prg + insn_length(*insn) != probe->nop_prg))

		/* JIT bug - gap between probe and nop instructions. */

		return -1;
@@ -763,7 +742,7 @@ static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp, 
			return -1;

		ex->fixup = delta;

		ex->type = EX_TYPE_BPF;

		ex->data = reg;

		ex->data = probe->reg;

		jit->excnt++;

	}

	return 0;
@@ -821,8 +800,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, 
	bpf_jit_probe_init(&probe);

	if (BPF_CLASS(insn->code) == BPF_LDX &&

	    (BPF_MODE(insn->code) == BPF_PROBE_MEM ||

	     BPF_MODE(insn->code) == BPF_PROBE_MEMSX))

	     BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) {

		probe.prg = jit->prg;

		probe.reg = reg2hex[dst_reg];

	}



	switch (insn->code) {

	/*