mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-16 09:02:21 -04:00
Code Issues Packages Projects Releases Wiki Activity

powerpc64/bpf: Implement fsession support

Browse Source 
Implement JIT support for fsession in powerpc64 trampoline.
The trampoline stack now accommodate session cookies and
function metadata in place of function argument. fentry/fexit
programs consume corresponding function metadata. This mirrors
existing x86 behavior and enable session cookies on powerpc64.

# ./test_progs -t fsession
#135/1   fsession_test/fsession_test:OK
#135/2   fsession_test/fsession_reattach:OK
#135/3   fsession_test/fsession_cookie:OK
#135     fsession_test:OK
Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260401141043.41513-1-adubey@linux.ibm.com
This commit is contained in:
Abhishek Dubey
2026-04-01 10:10:42 -04:00
committed by Madhavan Srinivasan
parent e640bcd1bf
commit 6fab063bd8
3 changed files with 87 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
arch/powerpc/net/bpf_jit.h
View File

@@ -218,7 +218,9 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx);
void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx);
void bpf_jit_realloc_regs(struct codegen_context *ctx);
int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr);
void prepare_for_fsession_fentry(u32 *image, struct codegen_context *ctx, int cookie_cnt,
int cookie_off, int retval_off);
void store_func_meta(u32 *image, struct codegen_context *ctx, u64 func_meta, int func_meta_off);
int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass,
struct codegen_context *ctx, int insn_idx,
int jmp_off, int dst_reg, u32 code);

69
arch/powerpc/net/bpf_jit_comp.c
View File

@@ -540,6 +540,11 @@ bool bpf_jit_supports_private_stack(void)
return IS_ENABLED(CONFIG_PPC64);
}
bool bpf_jit_supports_fsession(void)
{
return IS_ENABLED(CONFIG_PPC64);
}
bool bpf_jit_supports_arena(void)
{
return IS_ENABLED(CONFIG_PPC64);
@@ -812,12 +817,16 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
struct bpf_tramp_links *tlinks,
void *func_addr)
{
int regs_off, nregs_off, ip_off, run_ctx_off, retval_off, nvr_off, alt_lr_off, r4_off = 0;
int regs_off, func_meta_off, ip_off, run_ctx_off, retval_off;
int nvr_off, alt_lr_off, r4_off = 0;
struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
int i, ret, nr_regs, retaddr_off, bpf_frame_size = 0;
struct codegen_context codegen_ctx, *ctx;
int cookie_off, cookie_cnt, cookie_ctx_off;
int fsession_cnt = bpf_fsession_cnt(tlinks);
u64 func_meta;
u32 *image = (u32 *)rw_image;
ppc_inst_t branch_insn;
u32 *branches = NULL;
@@ -853,9 +862,11 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
* [ reg argN ]
* [ ... ]
* regs_off [ reg_arg1 ] prog_ctx
* nregs_off [ args count ] ((u64 *)prog_ctx)[-1]
* func_meta_off [ args count ] ((u64 *)prog_ctx)[-1]
* ip_off [ traced function ] ((u64 *)prog_ctx)[-2]
* [ stack cookieN ]
* [ ... ]
* cookie_off [ stack cookie1 ]
* run_ctx_off [ bpf_tramp_run_ctx ]
* [ reg argN ]
* [ ... ]
@@ -887,16 +898,21 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
run_ctx_off = bpf_frame_size;
bpf_frame_size += round_up(sizeof(struct bpf_tramp_run_ctx), SZL);
/* room for session cookies */
cookie_off = bpf_frame_size;
cookie_cnt = bpf_fsession_cookie_cnt(tlinks);
bpf_frame_size += cookie_cnt * 8;
/* Room for IP address argument */
ip_off = bpf_frame_size;
if (flags & BPF_TRAMP_F_IP_ARG)
bpf_frame_size += SZL;
/* Room for args count */
nregs_off = bpf_frame_size;
/* Room for function metadata, arg regs count */
func_meta_off = bpf_frame_size;
bpf_frame_size += SZL;
/* Room for args */
/* Room for arg regs */
regs_off = bpf_frame_size;
bpf_frame_size += nr_regs * SZL;
@@ -995,9 +1011,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
EMIT(PPC_RAW_STL(_R3, _R1, retaddr_off));
}
/* Save function arg count -- see bpf_get_func_arg_cnt() */
EMIT(PPC_RAW_LI(_R3, nr_regs));
EMIT(PPC_RAW_STL(_R3, _R1, nregs_off));
/* Save function arg regs count -- see bpf_get_func_arg_cnt() */
func_meta = nr_regs;
store_func_meta(image, ctx, func_meta, func_meta_off);
/* Save nv regs */
EMIT(PPC_RAW_STL(_R25, _R1, nvr_off));
@@ -1011,10 +1027,28 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
return ret;
}
for (i = 0; i < fentry->nr_links; i++)
if (fsession_cnt) {
/*
* Clear all the session cookies' values
* Clear the return value to make sure fentry always get 0
*/
prepare_for_fsession_fentry(image, ctx, cookie_cnt, cookie_off, retval_off);
}
cookie_ctx_off = (regs_off - cookie_off) / 8;
for (i = 0; i < fentry->nr_links; i++) {
if (bpf_prog_calls_session_cookie(fentry->links[i])) {
u64 meta = func_meta | (cookie_ctx_off << BPF_TRAMP_COOKIE_INDEX_SHIFT);
store_func_meta(image, ctx, meta, func_meta_off);
cookie_ctx_off--;
}
if (invoke_bpf_prog(image, ro_image, ctx, fentry->links[i], regs_off, retval_off,
run_ctx_off, flags & BPF_TRAMP_F_RET_FENTRY_RET))
return -EINVAL;
}
if (fmod_ret->nr_links) {
branches = kcalloc(fmod_ret->nr_links, sizeof(u32), GFP_KERNEL);
@@ -1076,12 +1110,27 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
image[branches[i]] = ppc_inst_val(branch_insn);
}
for (i = 0; i < fexit->nr_links; i++)
/* set the "is_return" flag for fsession */
func_meta |= (1ULL << BPF_TRAMP_IS_RETURN_SHIFT);
if (fsession_cnt)
store_func_meta(image, ctx, func_meta, func_meta_off);
cookie_ctx_off = (regs_off - cookie_off) / 8;
for (i = 0; i < fexit->nr_links; i++) {
if (bpf_prog_calls_session_cookie(fexit->links[i])) {
u64 meta = func_meta | (cookie_ctx_off << BPF_TRAMP_COOKIE_INDEX_SHIFT);
store_func_meta(image, ctx, meta, func_meta_off);
cookie_ctx_off--;
}
if (invoke_bpf_prog(image, ro_image, ctx, fexit->links[i], regs_off, retval_off,
run_ctx_off, false)) {
ret = -EINVAL;
goto cleanup;
}
}
if (flags & BPF_TRAMP_F_CALL_ORIG) {
if (ro_image) /* image is NULL for dummy pass */

25
arch/powerpc/net/bpf_jit_comp64.c
View File

@@ -179,6 +179,31 @@ static int bpf_jit_stack_offsetof(struct codegen_context *ctx, int reg)
BUG();
}
void prepare_for_fsession_fentry(u32 *image, struct codegen_context *ctx, int cookie_cnt,
int cookie_off, int retval_off)
{
EMIT(PPC_RAW_LI(bpf_to_ppc(TMP_REG_1), 0));
for (int i = 0; i < cookie_cnt; i++)
EMIT(PPC_RAW_STD(bpf_to_ppc(TMP_REG_1), _R1, cookie_off + 8 * i));
EMIT(PPC_RAW_STD(bpf_to_ppc(TMP_REG_1), _R1, retval_off));
}
void store_func_meta(u32 *image, struct codegen_context *ctx,
u64 func_meta, int func_meta_off)
{
/*
* Store func_meta to stack at [R1 + func_meta_off] = func_meta
*
* func_meta :
* bit[63]: is_return flag
* byte[1]: cookie offset from ctx
* byte[0]: args count
*/
PPC_LI64(bpf_to_ppc(TMP_REG_1), func_meta);
EMIT(PPC_RAW_STD(bpf_to_ppc(TMP_REG_1), _R1, func_meta_off));
}
void bpf_jit_realloc_regs(struct codegen_context *ctx)
{
}