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path: root/arch/x86/net/bpf_jit_comp.c
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Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
-rw-r--r--arch/x86/net/bpf_jit_comp.c66
1 files changed, 48 insertions, 18 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 0fe6aacef3db..9ea57389c554 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1341,9 +1341,10 @@ st: if (is_imm8(insn->off))
if (insn->imm == (BPF_AND | BPF_FETCH) ||
insn->imm == (BPF_OR | BPF_FETCH) ||
insn->imm == (BPF_XOR | BPF_FETCH)) {
- u8 *branch_target;
bool is64 = BPF_SIZE(insn->code) == BPF_DW;
u32 real_src_reg = src_reg;
+ u32 real_dst_reg = dst_reg;
+ u8 *branch_target;
/*
* Can't be implemented with a single x86 insn.
@@ -1354,11 +1355,13 @@ st: if (is_imm8(insn->off))
emit_mov_reg(&prog, true, BPF_REG_AX, BPF_REG_0);
if (src_reg == BPF_REG_0)
real_src_reg = BPF_REG_AX;
+ if (dst_reg == BPF_REG_0)
+ real_dst_reg = BPF_REG_AX;
branch_target = prog;
/* Load old value */
emit_ldx(&prog, BPF_SIZE(insn->code),
- BPF_REG_0, dst_reg, insn->off);
+ BPF_REG_0, real_dst_reg, insn->off);
/*
* Perform the (commutative) operation locally,
* put the result in the AUX_REG.
@@ -1369,7 +1372,8 @@ st: if (is_imm8(insn->off))
add_2reg(0xC0, AUX_REG, real_src_reg));
/* Attempt to swap in new value */
err = emit_atomic(&prog, BPF_CMPXCHG,
- dst_reg, AUX_REG, insn->off,
+ real_dst_reg, AUX_REG,
+ insn->off,
BPF_SIZE(insn->code));
if (WARN_ON(err))
return err;
@@ -1383,11 +1387,10 @@ st: if (is_imm8(insn->off))
/* Restore R0 after clobbering RAX */
emit_mov_reg(&prog, true, BPF_REG_0, BPF_REG_AX);
break;
-
}
err = emit_atomic(&prog, insn->imm, dst_reg, src_reg,
- insn->off, BPF_SIZE(insn->code));
+ insn->off, BPF_SIZE(insn->code));
if (err)
return err;
break;
@@ -1744,7 +1747,7 @@ static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
}
static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
- struct bpf_prog *p, int stack_size, bool mod_ret)
+ struct bpf_prog *p, int stack_size, bool save_ret)
{
u8 *prog = *pprog;
u8 *jmp_insn;
@@ -1777,11 +1780,15 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
if (emit_call(&prog, p->bpf_func, prog))
return -EINVAL;
- /* BPF_TRAMP_MODIFY_RETURN trampolines can modify the return
+ /*
+ * BPF_TRAMP_MODIFY_RETURN trampolines can modify the return
* of the previous call which is then passed on the stack to
* the next BPF program.
+ *
+ * BPF_TRAMP_FENTRY trampoline may need to return the return
+ * value of BPF_PROG_TYPE_STRUCT_OPS prog.
*/
- if (mod_ret)
+ if (save_ret)
emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
/* replace 2 nops with JE insn, since jmp target is known */
@@ -1828,13 +1835,15 @@ static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond)
}
static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,
- struct bpf_tramp_progs *tp, int stack_size)
+ struct bpf_tramp_progs *tp, int stack_size,
+ bool save_ret)
{
int i;
u8 *prog = *pprog;
for (i = 0; i < tp->nr_progs; i++) {
- if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size, false))
+ if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size,
+ save_ret))
return -EINVAL;
}
*pprog = prog;
@@ -1877,6 +1886,23 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
return 0;
}
+static bool is_valid_bpf_tramp_flags(unsigned int flags)
+{
+ if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
+ (flags & BPF_TRAMP_F_SKIP_FRAME))
+ return false;
+
+ /*
+ * BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
+ * and it must be used alone.
+ */
+ if ((flags & BPF_TRAMP_F_RET_FENTRY_RET) &&
+ (flags & ~BPF_TRAMP_F_RET_FENTRY_RET))
+ return false;
+
+ return true;
+}
+
/* Example:
* __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
* its 'struct btf_func_model' will be nr_args=2
@@ -1949,17 +1975,19 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
struct bpf_tramp_progs *fmod_ret = &tprogs[BPF_TRAMP_MODIFY_RETURN];
u8 **branches = NULL;
u8 *prog;
+ bool save_ret;
/* x86-64 supports up to 6 arguments. 7+ can be added in the future */
if (nr_args > 6)
return -ENOTSUPP;
- if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
- (flags & BPF_TRAMP_F_SKIP_FRAME))
+ if (!is_valid_bpf_tramp_flags(flags))
return -EINVAL;
- if (flags & BPF_TRAMP_F_CALL_ORIG)
- stack_size += 8; /* room for return value of orig_call */
+ /* room for return value of orig_call or fentry prog */
+ save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
+ if (save_ret)
+ stack_size += 8;
if (flags & BPF_TRAMP_F_IP_ARG)
stack_size += 8; /* room for IP address argument */
@@ -2005,7 +2033,8 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
}
if (fentry->nr_progs)
- if (invoke_bpf(m, &prog, fentry, stack_size))
+ if (invoke_bpf(m, &prog, fentry, stack_size,
+ flags & BPF_TRAMP_F_RET_FENTRY_RET))
return -EINVAL;
if (fmod_ret->nr_progs) {
@@ -2052,7 +2081,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
}
if (fexit->nr_progs)
- if (invoke_bpf(m, &prog, fexit, stack_size)) {
+ if (invoke_bpf(m, &prog, fexit, stack_size, false)) {
ret = -EINVAL;
goto cleanup;
}
@@ -2072,9 +2101,10 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
ret = -EINVAL;
goto cleanup;
}
- /* restore original return value back into RAX */
- emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8);
}
+ /* restore return value of orig_call or fentry prog back into RAX */
+ if (save_ret)
+ emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8);
EMIT1(0x5B); /* pop rbx */
EMIT1(0xC9); /* leave */
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