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bpf: Prepare architecture JIT support for stack arguments

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Add bpf_jit_supports_stack_args() as a weak function defaulting to
false. Architectures that implement JIT support for stack arguments
override it to return true.

Reject BPF functions with more than 5 parameters at verification
time if the architecture does not support stack arguments.

Acked-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045054.2390945-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2026-05-12 21:50:54 -07:00 committed by Alexei Starovoitov
parent dc8f1cf678
commit 848d624acf
3 changed files with 13 additions and 1 deletions
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1
include/linux/filter.h
View File

@ -1184,6 +1184,7 @@ bool bpf_jit_inlines_helper_call(s32 imm);
bool bpf_jit_supports_subprog_tailcalls(void);
bool bpf_jit_supports_percpu_insn(void);
bool bpf_jit_supports_kfunc_call(void);
bool bpf_jit_supports_stack_args(void);
bool bpf_jit_supports_far_kfunc_call(void);
bool bpf_jit_supports_exceptions(void);
bool bpf_jit_supports_ptr_xchg(void);

8
kernel/bpf/btf.c
View File

@ -7870,8 +7870,14 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
MAX_BPF_FUNC_ARGS, tname, nargs);
return -EFAULT;
}
if (nargs > MAX_BPF_FUNC_REG_ARGS)
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
if (!bpf_jit_supports_stack_args()) {
bpf_log(log, "JIT does not support function %s() with %d args\n",
tname, nargs);
return -EFAULT;
}
sub->stack_arg_cnt = nargs - MAX_BPF_FUNC_REG_ARGS;
}
if (is_global && nargs > MAX_BPF_FUNC_REG_ARGS) {
bpf_log(log, "global function %s has %d > %d args, stack args not supported\n",

5
kernel/bpf/core.c
View File

@ -3217,6 +3217,11 @@ bool __weak bpf_jit_supports_kfunc_call(void)
return false;
}
bool __weak bpf_jit_supports_stack_args(void)
{
return false;
}
bool __weak bpf_jit_supports_far_kfunc_call(void)
{
return false;