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bpf,s390: add fsession support for trampolines

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Implement BPF_TRACE_FSESSION support for s390. The logic here is similar
to what we did in x86_64.

In order to simply the logic, we factor out the function invoke_bpf() for
fentry and fexit.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20260224092208.1395085-3-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Menglong Dong 2026-02-24 17:22:07 +08:00 committed by Alexei Starovoitov
parent 339193c44e
commit 63d2b7d101
1 changed files with 60 additions and 14 deletions
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74
arch/s390/net/bpf_jit_comp.c
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@ -2487,8 +2487,8 @@ struct bpf_tramp_jit {
int ip_off; /* For bpf_get_func_ip(), has to be at
* (ctx - 16)
*/
int arg_cnt_off; /* For bpf_get_func_arg_cnt(), has to be at
* (ctx - 8)
int func_meta_off; /* For bpf_get_func_arg_cnt()/fsession, has
* to be at (ctx - 8)
*/
int bpf_args_off; /* Offset of BPF_PROG context, which consists
* of BPF arguments followed by return value
@ -2592,6 +2592,28 @@ static int invoke_bpf_prog(struct bpf_tramp_jit *tjit,
return 0;
}
static int invoke_bpf(struct bpf_tramp_jit *tjit,
const struct btf_func_model *m,
struct bpf_tramp_links *tl, bool save_ret,
u64 func_meta, int cookie_off)
{
int i, cur_cookie = (tjit->bpf_args_off - cookie_off) / sizeof(u64);
struct bpf_jit *jit = &tjit->common;
for (i = 0; i < tl->nr_links; i++) {
if (bpf_prog_calls_session_cookie(tl->links[i])) {
u64 meta = func_meta | ((u64)cur_cookie << BPF_TRAMP_COOKIE_INDEX_SHIFT);
emit_store_stack_imm64(jit, REG_0, tjit->func_meta_off, meta);
cur_cookie--;
}
if (invoke_bpf_prog(tjit, m, tl->links[i], save_ret))
return -EINVAL;
}
return 0;
}
static int alloc_stack(struct bpf_tramp_jit *tjit, size_t size)
{
int stack_offset = tjit->stack_size;
@ -2621,8 +2643,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
int nr_bpf_args, nr_reg_args, nr_stack_args;
int cookie_cnt, cookie_off, fsession_cnt;
struct bpf_jit *jit = &tjit->common;
int arg, bpf_arg_off;
u64 func_meta;
int i, j;
/* Support as many stack arguments as "mvc" instruction can handle. */
@ -2654,6 +2678,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
return -ENOTSUPP;
}
cookie_cnt = bpf_fsession_cookie_cnt(tlinks);
fsession_cnt = bpf_fsession_cnt(tlinks);
/*
* Calculate the stack layout.
*/
@ -2666,8 +2693,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
tjit->backchain_off = tjit->stack_size - sizeof(u64);
tjit->stack_args_off = alloc_stack(tjit, nr_stack_args * sizeof(u64));
tjit->reg_args_off = alloc_stack(tjit, nr_reg_args * sizeof(u64));
cookie_off = alloc_stack(tjit, cookie_cnt * sizeof(u64));
tjit->ip_off = alloc_stack(tjit, sizeof(u64));
tjit->arg_cnt_off = alloc_stack(tjit, sizeof(u64));
tjit->func_meta_off = alloc_stack(tjit, sizeof(u64));
tjit->bpf_args_off = alloc_stack(tjit, nr_bpf_args * sizeof(u64));
tjit->retval_off = alloc_stack(tjit, sizeof(u64));
tjit->r7_r8_off = alloc_stack(tjit, 2 * sizeof(u64));
@ -2756,11 +2784,12 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
if (flags & BPF_TRAMP_F_IP_ARG)
emit_store_stack_imm64(jit, REG_0, tjit->ip_off, (u64)func_addr);
/* lghi %r0,nr_bpf_args */
EMIT4_IMM(0xa7090000, REG_0, nr_bpf_args);
/* stg %r0,arg_cnt_off(%r15) */
func_meta = nr_bpf_args;
/* lghi %r0,func_meta */
EMIT4_IMM(0xa7090000, REG_0, func_meta);
/* stg %r0,func_meta_off(%r15) */
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_0, REG_0, REG_15,
tjit->arg_cnt_off);
tjit->func_meta_off);
if (flags & BPF_TRAMP_F_CALL_ORIG) {
/*
@ -2773,10 +2802,17 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
EMIT6_PCREL_RILB_PTR(0xc0050000, REG_14, __bpf_tramp_enter);
}
for (i = 0; i < fentry->nr_links; i++)
if (invoke_bpf_prog(tjit, m, fentry->links[i],
flags & BPF_TRAMP_F_RET_FENTRY_RET))
return -EINVAL;
if (fsession_cnt) {
/* Clear all the session cookies' value. */
for (i = 0; i < cookie_cnt; i++)
emit_store_stack_imm64(jit, REG_0, cookie_off + 8 * i, 0);
/* Clear the return value to make sure fentry always gets 0. */
emit_store_stack_imm64(jit, REG_0, tjit->retval_off, 0);
}
if (invoke_bpf(tjit, m, fentry, flags & BPF_TRAMP_F_RET_FENTRY_RET,
func_meta, cookie_off))
return -EINVAL;
if (fmod_ret->nr_links) {
/*
@ -2853,11 +2889,16 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
EMIT6_PCREL_RILC(0xc0040000, 0, (u64)im->ip_epilogue);
}
/* Set the "is_return" flag for fsession. */
func_meta |= (1ULL << BPF_TRAMP_IS_RETURN_SHIFT);
if (fsession_cnt)
emit_store_stack_imm64(jit, REG_W0, tjit->func_meta_off,
func_meta);
/* do_fexit: */
tjit->do_fexit = jit->prg;
for (i = 0; i < fexit->nr_links; i++)
if (invoke_bpf_prog(tjit, m, fexit->links[i], false))
return -EINVAL;
if (invoke_bpf(tjit, m, fexit, false, func_meta, cookie_off))
return -EINVAL;
if (flags & BPF_TRAMP_F_CALL_ORIG) {
im->ip_epilogue = jit->prg_buf + jit->prg;
@ -2962,6 +3003,11 @@ bool bpf_jit_supports_arena(void)
return true;
}
bool bpf_jit_supports_fsession(void)
{
return true;
}
bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena)
{
if (!in_arena)