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LoongArch: BPF: Add arch_bpf_stack_walk() implementation

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Implement arch_bpf_stack_walk() on top of the ORC unwinder within
the LoongArch BPF JIT backend to provide generic BPF stack walking
capabilities.

This function is required by advanced BPF features, including timed
may_goto timeout tracing and BPF exceptions. It will be invoked in
the BPF core subsystem unwinding paths: bpf_prog_find_from_stack(),
bpf_stream_stage_dump_stack(), and bpf_throw().

Co-developed-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
George Guo 2026-08-17 22:07:40 +08:00 committed by Huacai Chen
parent 3fbf3534c2
commit e7103e5e3b
1 changed files with 38 additions and 0 deletions
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38
arch/loongarch/net/bpf_jit.c
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@ -2366,6 +2366,44 @@ void bpf_jit_free(struct bpf_prog *prog)
bpf_prog_unlock_free(prog);
}
#if defined(CONFIG_UNWINDER_ORC)
#include <asm/unwind.h>
static noinline void walk_bpf_stackframe(bool (*consume_fn)(void *cookie, u64 ip, u64 sp, u64 bp),
void *cookie, unsigned long fp)
{
unsigned long addr;
struct unwind_state state;
struct pt_regs dummyregs;
struct pt_regs *regs = &dummyregs;
regs->regs[1] = 0;
regs->regs[22] = fp;
regs->regs[3] = (unsigned long)__builtin_frame_address(0);
regs->csr_era = (unsigned long)__builtin_return_address(0);
for (unwind_start(&state, current, regs);
!unwind_done(&state); unwind_next_frame(&state)) {
addr = unwind_get_return_address(&state);
if (!addr || !consume_fn(cookie, (u64)addr, (u64)state.sp, (u64)state.fp))
break;
}
}
void arch_bpf_stack_walk(bool (*consume_fn)(void *cookie, u64 ip, u64 sp, u64 bp), void *cookie)
{
unsigned long fp;
/*
* Capture the live frame pointer ($r22) at the very front-line before
* any kernel C code clobbers it. This must be a thin wrapper with no
* large stack locals to prevent the compiler from reusing $r22 early.
*/
asm volatile("move %0, $r22" : "=r"(fp));
walk_bpf_stackframe(consume_fn, cookie, fp);
}
#endif /* CONFIG_UNWINDER_ORC */
bool bpf_jit_bypass_spec_v1(void)
{
return true;