superrob1500
/
mirror-linux
mirror of https://github.com/torvalds/linux
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

bpf,x86: add fsession support for x86_64 

Add BPF_TRACE_FSESSION supporting to x86_64, including:

1. clear the return value in the stack before fentry to make the fentry
   of the fsession can only get 0 with bpf_get_func_ret().

2. clear all the session cookies' value in the stack.

2. store the index of the cookie to ctx[-1] before the calling to fsession

3. store the "is_return" flag to ctx[-1] before the calling to fexit of
   the fsession.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Co-developed-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260124062008.8657-8-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
master
Menglong Dong 2026-01-24 14:20:02 +08:00 committed by Alexei Starovoitov
parent 37c7ba1b39
commit 98770bd4e6
1 changed files with 40 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
arch/x86/net/bpf_jit_comp.c
View File

@ -3094,13 +3094,19 @@ 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_links *tl, int stack_size,
int run_ctx_off, bool save_ret,
void *image, void *rw_image)
int run_ctx_off, int func_meta_off, bool save_ret,
void *image, void *rw_image, u64 func_meta,
int cookie_off)
{
int i;
int i, cur_cookie = (cookie_off - stack_size) / 8;
u8 *prog = *pprog;
for (i = 0; i < tl->nr_links; i++) {
if (tl->links[i]->link.prog->call_session_cookie) {
emit_store_stack_imm64(&prog, BPF_REG_0, -func_meta_off,
func_meta | (cur_cookie << BPF_TRAMP_COOKIE_INDEX_SHIFT));
cur_cookie--;
}
if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size,
run_ctx_off, save_ret, image, rw_image))
return -EINVAL;
@ -3218,12 +3224,14 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
void *func_addr)
{
int i, ret, nr_regs = m->nr_args, stack_size = 0;
int regs_off, nregs_off, ip_off, run_ctx_off, arg_stack_off, rbx_off;
int regs_off, func_meta_off, ip_off, run_ctx_off, arg_stack_off, rbx_off;
struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
void *orig_call = func_addr;
int cookie_off, cookie_cnt;
u8 **branches = NULL;
u64 func_meta;
u8 *prog;
bool save_ret;
@ -3259,7 +3267,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
* [ ... ]
* RBP - regs_off [ reg_arg1 ] program's ctx pointer
*
* RBP - nregs_off [ regs count ] always
* RBP - func_meta_off [ regs count, etc ] always
*
* RBP - ip_off [ traced function ] BPF_TRAMP_F_IP_ARG flag
*
@ -3282,15 +3290,20 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
stack_size += nr_regs * 8;
regs_off = stack_size;
/* regs count */
/* function matedata, such as regs count */
stack_size += 8;
nregs_off = stack_size;
func_meta_off = stack_size;
if (flags & BPF_TRAMP_F_IP_ARG)
stack_size += 8; /* room for IP address argument */
ip_off = stack_size;
cookie_cnt = bpf_fsession_cookie_cnt(tlinks);
/* room for session cookies */
stack_size += cookie_cnt * 8;
cookie_off = stack_size;
stack_size += 8;
rbx_off = stack_size;
@ -3358,8 +3371,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
/* mov QWORD PTR [rbp - rbx_off], rbx */
emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_6, -rbx_off);
func_meta = nr_regs;
/* Store number of argument registers of the traced function */
emit_store_stack_imm64(&prog, BPF_REG_0, -nregs_off, nr_regs);
emit_store_stack_imm64(&prog, BPF_REG_0, -func_meta_off, func_meta);
if (flags & BPF_TRAMP_F_IP_ARG) {
/* Store IP address of the traced function */
@ -3378,9 +3392,18 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
}
}
if (bpf_fsession_cnt(tlinks)) {
/* clear all the session cookies' value */
for (int i = 0; i < cookie_cnt; i++)
emit_store_stack_imm64(&prog, BPF_REG_0, -cookie_off + 8 * i, 0);
/* clear the return value to make sure fentry always get 0 */
emit_store_stack_imm64(&prog, BPF_REG_0, -8, 0);
}
if (fentry->nr_links) {
if (invoke_bpf(m, &prog, fentry, regs_off, run_ctx_off,
flags & BPF_TRAMP_F_RET_FENTRY_RET, image, rw_image))
if (invoke_bpf(m, &prog, fentry, regs_off, run_ctx_off, func_meta_off,
flags & BPF_TRAMP_F_RET_FENTRY_RET, image, rw_image,
func_meta, cookie_off))
return -EINVAL;
}
@ -3440,9 +3463,14 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
}
}
/* set the "is_return" flag for fsession */
func_meta |= (1ULL << BPF_TRAMP_IS_RETURN_SHIFT);
if (bpf_fsession_cnt(tlinks))
emit_store_stack_imm64(&prog, BPF_REG_0, -func_meta_off, func_meta);
if (fexit->nr_links) {
if (invoke_bpf(m, &prog, fexit, regs_off, run_ctx_off,
false, image, rw_image)) {
if (invoke_bpf(m, &prog, fexit, regs_off, run_ctx_off, func_meta_off,
false, image, rw_image, func_meta, cookie_off)) {
ret = -EINVAL;
goto cleanup;
}