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Commit 4d3a453b authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Daniel Borkmann
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s390/bpf: Support BPF_PROBE_MEM32 

BPF_PROBE_MEM32 is a new mode for LDX, ST and STX instructions. The JIT
is supposed to add the start address of the kernel arena mapping to the
%dst register, and use a probing variant of the respective memory
access.

Reuse the existing probing infrastructure for that. Put the arena
address into the literal pool, load it into %r1 and use that as an
index register. Do not clear any registers in ex_handler_bpf() for
failing ST and STX instructions.
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/20240701234304.14336-7-iii@linux.ibm.com
parent a1c04bcc
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Showing with 110 additions and 27 deletions
arch/s390/net/bpf_jit_comp.c
View file @ 4d3a453b
......@@ -53,6 +53,7 @@ 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 */
int kern_arena; /* Pool offset of kernel arena address */
};
#define SEEN_MEM BIT(0) /* use mem[] for temporary storage */
......@@ -670,7 +671,8 @@ static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth)
bool ex_handler_bpf(const struct exception_table_entry *x, struct pt_regs *regs)
{
regs->psw.addr = extable_fixup(x);
regs->gprs[x->data] = 0;
if (x->data != -1)
regs->gprs[x->data] = 0;
return true;
}
......@@ -681,6 +683,7 @@ struct bpf_jit_probe {
int prg; /* JITed instruction offset */
int nop_prg; /* JITed nop offset */
int reg; /* Register to clear on exception */
int arena_reg; /* Register to use for arena addressing */
};
static void bpf_jit_probe_init(struct bpf_jit_probe *probe)
......@@ -688,6 +691,7 @@ static void bpf_jit_probe_init(struct bpf_jit_probe *probe)
probe->prg = -1;
probe->nop_prg = -1;
probe->reg = -1;
probe->arena_reg = REG_0;
}
/*
......@@ -708,13 +712,31 @@ static void bpf_jit_probe_load_pre(struct bpf_jit *jit, struct bpf_insn *insn,
struct bpf_jit_probe *probe)
{
if (BPF_MODE(insn->code) != BPF_PROBE_MEM &&
BPF_MODE(insn->code) != BPF_PROBE_MEMSX)
BPF_MODE(insn->code) != BPF_PROBE_MEMSX &&
BPF_MODE(insn->code) != BPF_PROBE_MEM32)
return;
if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) {
/* lgrl %r1,kern_arena */
EMIT6_PCREL_RILB(0xc4080000, REG_W1, jit->kern_arena);
probe->arena_reg = REG_W1;
}
probe->prg = jit->prg;
probe->reg = reg2hex[insn->dst_reg];
}
static void bpf_jit_probe_store_pre(struct bpf_jit *jit, struct bpf_insn *insn,
struct bpf_jit_probe *probe)
{
if (BPF_MODE(insn->code) != BPF_PROBE_MEM32)
return;
/* lgrl %r1,kern_arena */
EMIT6_PCREL_RILB(0xc4080000, REG_W1, jit->kern_arena);
probe->arena_reg = REG_W1;
probe->prg = jit->prg;
}
static int bpf_jit_probe_post(struct bpf_jit *jit, struct bpf_prog *fp,
struct bpf_jit_probe *probe)
{
......@@ -1384,51 +1406,99 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
* BPF_ST(X)
*/
case BPF_STX | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = src_reg */
/* stcy %src,off(%dst) */
EMIT6_DISP_LH(0xe3000000, 0x0072, src_reg, dst_reg, REG_0, off);
case BPF_STX | BPF_PROBE_MEM32 | BPF_B:
bpf_jit_probe_store_pre(jit, insn, &probe);
/* stcy %src,off(%dst,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0072, src_reg, dst_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
jit->seen |= SEEN_MEM;
break;
case BPF_STX | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = src */
/* sthy %src,off(%dst) */
EMIT6_DISP_LH(0xe3000000, 0x0070, src_reg, dst_reg, REG_0, off);
case BPF_STX | BPF_PROBE_MEM32 | BPF_H:
bpf_jit_probe_store_pre(jit, insn, &probe);
/* sthy %src,off(%dst,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0070, src_reg, dst_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
jit->seen |= SEEN_MEM;
break;
case BPF_STX | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = src */
/* sty %src,off(%dst) */
EMIT6_DISP_LH(0xe3000000, 0x0050, src_reg, dst_reg, REG_0, off);
case BPF_STX | BPF_PROBE_MEM32 | BPF_W:
bpf_jit_probe_store_pre(jit, insn, &probe);
/* sty %src,off(%dst,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0050, src_reg, dst_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
jit->seen |= SEEN_MEM;
break;
case BPF_STX | BPF_MEM | BPF_DW: /* (u64 *)(dst + off) = src */
/* stg %src,off(%dst) */
EMIT6_DISP_LH(0xe3000000, 0x0024, src_reg, dst_reg, REG_0, off);
case BPF_STX | BPF_PROBE_MEM32 | BPF_DW:
bpf_jit_probe_store_pre(jit, insn, &probe);
/* stg %src,off(%dst,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0024, src_reg, dst_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
jit->seen |= SEEN_MEM;
break;
case BPF_ST | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = imm */
case BPF_ST | BPF_PROBE_MEM32 | BPF_B:
/* lhi %w0,imm */
EMIT4_IMM(0xa7080000, REG_W0, (u8) imm);
/* stcy %w0,off(dst) */
EMIT6_DISP_LH(0xe3000000, 0x0072, REG_W0, dst_reg, REG_0, off);
bpf_jit_probe_store_pre(jit, insn, &probe);
/* stcy %w0,off(%dst,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0072, REG_W0, dst_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
jit->seen |= SEEN_MEM;
break;
case BPF_ST | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = imm */
case BPF_ST | BPF_PROBE_MEM32 | BPF_H:
/* lhi %w0,imm */
EMIT4_IMM(0xa7080000, REG_W0, (u16) imm);
/* sthy %w0,off(dst) */
EMIT6_DISP_LH(0xe3000000, 0x0070, REG_W0, dst_reg, REG_0, off);
bpf_jit_probe_store_pre(jit, insn, &probe);
/* sthy %w0,off(%dst,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0070, REG_W0, dst_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
jit->seen |= SEEN_MEM;
break;
case BPF_ST | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = imm */
case BPF_ST | BPF_PROBE_MEM32 | BPF_W:
/* llilf %w0,imm */
EMIT6_IMM(0xc00f0000, REG_W0, (u32) imm);
/* sty %w0,off(%dst) */
EMIT6_DISP_LH(0xe3000000, 0x0050, REG_W0, dst_reg, REG_0, off);
bpf_jit_probe_store_pre(jit, insn, &probe);
/* sty %w0,off(%dst,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0050, REG_W0, dst_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
jit->seen |= SEEN_MEM;
break;
case BPF_ST | BPF_MEM | BPF_DW: /* *(u64 *)(dst + off) = imm */
case BPF_ST | BPF_PROBE_MEM32 | BPF_DW:
/* lgfi %w0,imm */
EMIT6_IMM(0xc0010000, REG_W0, imm);
/* stg %w0,off(%dst) */
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W0, dst_reg, REG_0, off);
bpf_jit_probe_store_pre(jit, insn, &probe);
/* stg %w0,off(%dst,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W0, dst_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
jit->seen |= SEEN_MEM;
break;
/*
......@@ -1506,9 +1576,11 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
*/
case BPF_LDX | BPF_MEM | BPF_B: /* dst = *(u8 *)(ul) (src + off) */
case BPF_LDX | BPF_PROBE_MEM | BPF_B:
case BPF_LDX | BPF_PROBE_MEM32 | BPF_B:
bpf_jit_probe_load_pre(jit, insn, &probe);
/* llgc %dst,0(off,%src) */
EMIT6_DISP_LH(0xe3000000, 0x0090, dst_reg, src_reg, REG_0, off);
/* llgc %dst,off(%src,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0090, dst_reg, src_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
......@@ -1519,7 +1591,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
case BPF_LDX | BPF_MEMSX | BPF_B: /* dst = *(s8 *)(ul) (src + off) */
case BPF_LDX | BPF_PROBE_MEMSX | BPF_B:
bpf_jit_probe_load_pre(jit, insn, &probe);
/* lgb %dst,0(off,%src) */
/* lgb %dst,off(%src) */
EMIT6_DISP_LH(0xe3000000, 0x0077, dst_reg, src_reg, REG_0, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
......@@ -1528,9 +1600,11 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
break;
case BPF_LDX | BPF_MEM | BPF_H: /* dst = *(u16 *)(ul) (src + off) */
case BPF_LDX | BPF_PROBE_MEM | BPF_H:
case BPF_LDX | BPF_PROBE_MEM32 | BPF_H:
bpf_jit_probe_load_pre(jit, insn, &probe);
/* llgh %dst,0(off,%src) */
EMIT6_DISP_LH(0xe3000000, 0x0091, dst_reg, src_reg, REG_0, off);
/* llgh %dst,off(%src,%arena) */
EMIT6_DISP_LH(0xe3000000, 0x0091, dst_reg, src_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
......@@ -1541,7 +1615,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
case BPF_LDX | BPF_MEMSX | BPF_H: /* dst = *(s16 *)(ul) (src + off) */
case BPF_LDX | BPF_PROBE_MEMSX | BPF_H:
bpf_jit_probe_load_pre(jit, insn, &probe);
/* lgh %dst,0(off,%src) */
/* lgh %dst,off(%src) */
EMIT6_DISP_LH(0xe3000000, 0x0015, dst_reg, src_reg, REG_0, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
......@@ -1550,10 +1624,12 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
break;
case BPF_LDX | BPF_MEM | BPF_W: /* dst = *(u32 *)(ul) (src + off) */
case BPF_LDX | BPF_PROBE_MEM | BPF_W:
case BPF_LDX | BPF_PROBE_MEM32 | BPF_W:
bpf_jit_probe_load_pre(jit, insn, &probe);
/* llgf %dst,off(%src) */
jit->seen |= SEEN_MEM;
EMIT6_DISP_LH(0xe3000000, 0x0016, dst_reg, src_reg, REG_0, off);
EMIT6_DISP_LH(0xe3000000, 0x0016, dst_reg, src_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
......@@ -1572,10 +1648,12 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
break;
case BPF_LDX | BPF_MEM | BPF_DW: /* dst = *(u64 *)(ul) (src + off) */
case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
case BPF_LDX | BPF_PROBE_MEM32 | BPF_DW:
bpf_jit_probe_load_pre(jit, insn, &probe);
/* lg %dst,0(off,%src) */
/* lg %dst,off(%src,%arena) */
jit->seen |= SEEN_MEM;
EMIT6_DISP_LH(0xe3000000, 0x0004, dst_reg, src_reg, REG_0, off);
EMIT6_DISP_LH(0xe3000000, 0x0004, dst_reg, src_reg,
probe.arena_reg, off);
err = bpf_jit_probe_post(jit, fp, &probe);
if (err < 0)
return err;
......@@ -1988,12 +2066,17 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp,
bool extra_pass, u32 stack_depth)
{
int i, insn_count, lit32_size, lit64_size;
u64 kern_arena;
jit->lit32 = jit->lit32_start;
jit->lit64 = jit->lit64_start;
jit->prg = 0;
jit->excnt = 0;
kern_arena = bpf_arena_get_kern_vm_start(fp->aux->arena);
if (kern_arena)
jit->kern_arena = _EMIT_CONST_U64(kern_arena);
bpf_jit_prologue(jit, fp, stack_depth);
if (bpf_set_addr(jit, 0) < 0)
return -1;
......
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