* [PATCH 1/3] powerpc64/bpf: Implement fsession support
@ 2026-02-16 15:53 adubey
2026-02-16 15:53 ` [PATCH 2/3] selftest/bpf: Enable get_func_args and get_func_ip tests on powerpc64 adubey
2026-02-16 15:53 ` [PATCH 3/3] powerpc32/bpf: Add fsession support adubey
0 siblings, 2 replies; 3+ messages in thread
From: adubey @ 2026-02-16 15:53 UTC (permalink / raw)
To: bpf
Cc: hbathini, linuxppc-dev, ast, daniel, andrii, martin.lau, eddyz87,
yonghong.song, clm, ihor.solodrai, chleroy, Abhishek Dubey
From: Abhishek Dubey <adubey@linux.ibm.com>
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.
Patch rebased over:
https://lore.kernel.org/bpf/20260216065639.1750181-1-hbathini@linux.ibm.com/T/#mf02cad9096fa4ad1f05610b1f464da1cddf7445a
Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
---
arch/powerpc/net/bpf_jit.h | 4 +-
arch/powerpc/net/bpf_jit_comp.c | 68 ++++++++++++++++++++++++++-----
arch/powerpc/net/bpf_jit_comp64.c | 25 ++++++++++++
3 files changed, 85 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index 5a115c54e43a..884027343da8 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h
@@ -217,7 +217,9 @@ 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);
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 629c263a054b..65e091064fe4 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -527,6 +527,11 @@ 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);
@@ -798,12 +803,15 @@ 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, 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;
@@ -839,9 +847,11 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
* [ reg argN ]
* [ ... ]
* regs_off [ reg_arg1 ] prog ctx context
- * 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 ]
* [ ... ]
@@ -873,16 +883,21 @@ 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 egs */
regs_off = bpf_frame_size;
bpf_frame_size += nr_regs * SZL;
@@ -976,9 +991,9 @@ 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));
@@ -992,10 +1007,27 @@ 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);
@@ -1057,12 +1089,26 @@ 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 */
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 206ef43b4090..1b397715206d 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -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)
{
}
--
2.52.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 2/3] selftest/bpf: Enable get_func_args and get_func_ip tests on powerpc64
2026-02-16 15:53 [PATCH 1/3] powerpc64/bpf: Implement fsession support adubey
@ 2026-02-16 15:53 ` adubey
2026-02-16 15:53 ` [PATCH 3/3] powerpc32/bpf: Add fsession support adubey
1 sibling, 0 replies; 3+ messages in thread
From: adubey @ 2026-02-16 15:53 UTC (permalink / raw)
To: bpf
Cc: hbathini, linuxppc-dev, ast, daniel, andrii, martin.lau, eddyz87,
yonghong.song, clm, ihor.solodrai, chleroy, Abhishek Dubey
From: Abhishek Dubey <adubey@linux.ibm.com>
Allow get_func_args, and get_func_ip fsession selftests to run 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
# ./test_progs -t get_func
#138 get_func_args_test:OK
#139 get_func_ip_test:OK
Summary: 2/0 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
---
tools/testing/selftests/bpf/progs/get_func_args_test.c | 2 +-
tools/testing/selftests/bpf/progs/get_func_ip_test.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/progs/get_func_args_test.c b/tools/testing/selftests/bpf/progs/get_func_args_test.c
index 180ba5098ca1..5579141ea45e 100644
--- a/tools/testing/selftests/bpf/progs/get_func_args_test.c
+++ b/tools/testing/selftests/bpf/progs/get_func_args_test.c
@@ -167,7 +167,7 @@ int BPF_PROG(tp_test2)
}
__u64 test7_result = 0;
-#if defined(bpf_target_x86) || defined(bpf_target_arm64)
+#if defined(bpf_target_x86) || defined(bpf_target_arm64) || defined(bpf_target_powerpc64)
SEC("fsession/bpf_fentry_test1")
int BPF_PROG(test7)
{
diff --git a/tools/testing/selftests/bpf/progs/get_func_ip_test.c b/tools/testing/selftests/bpf/progs/get_func_ip_test.c
index 43ff836a8ed8..2558dda4d82c 100644
--- a/tools/testing/selftests/bpf/progs/get_func_ip_test.c
+++ b/tools/testing/selftests/bpf/progs/get_func_ip_test.c
@@ -106,7 +106,7 @@ int BPF_URETPROBE(test8, int ret)
__u64 test9_entry_result = 0;
__u64 test9_exit_result = 0;
-#if defined(bpf_target_x86) || defined(bpf_target_arm64)
+#if defined(bpf_target_x86) || defined(bpf_target_arm64) || defined(bpf_target_powerpc64)
SEC("fsession/bpf_fentry_test1")
int BPF_PROG(test9, int a)
{
--
2.52.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 3/3] powerpc32/bpf: Add fsession support
2026-02-16 15:53 [PATCH 1/3] powerpc64/bpf: Implement fsession support adubey
2026-02-16 15:53 ` [PATCH 2/3] selftest/bpf: Enable get_func_args and get_func_ip tests on powerpc64 adubey
@ 2026-02-16 15:53 ` adubey
1 sibling, 0 replies; 3+ messages in thread
From: adubey @ 2026-02-16 15:53 UTC (permalink / raw)
To: bpf
Cc: hbathini, linuxppc-dev, ast, daniel, andrii, martin.lau, eddyz87,
yonghong.song, clm, ihor.solodrai, chleroy, Abhishek Dubey
From: Abhishek Dubey <adubey@linux.ibm.com>
Extend JIT support of fsession in powerpc64 trampoline, since
ppc64 and ppc32 shares common trampoline implementation.
Arch specific helpers handle 64-bit data copy using 32 bit regs.
Need to validate fsession support along with trampoline support.
Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
---
arch/powerpc/net/bpf_jit_comp.c | 8 ++++++-
arch/powerpc/net/bpf_jit_comp32.c | 35 +++++++++++++++++++++++++++++++
2 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 65e091064fe4..31896ed34129 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -529,7 +529,13 @@ bool bpf_jit_supports_private_stack(void)
bool bpf_jit_supports_fsession(void)
{
- return IS_ENABLED(CONFIG_PPC64);
+ /*
+ * TODO: Remove after validating support
+ * for fsession and trampoline on ppc32.
+ */
+ if (IS_ENABLED(CONFIG_PPC32))
+ return -EOPNOTSUPP;
+ return true;
}
bool bpf_jit_supports_arena(void)
diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index 3087e744fb25..72dc2a55d66c 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -123,6 +123,41 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx)
}
}
+void prepare_for_fsession_fentry(u32 *image, struct codegen_context *ctx, int cookie_cnt,
+ int cookie_off, int retval_off)
+{
+ /*
+ * Set session cookies value
+ * Clear cookies field on stack
+ * Ensure retval to be cleared on fentry
+ */
+ EMIT(PPC_RAW_LI(bpf_to_ppc(TMP_REG), 0));
+
+ for (int i = 0; i < cookie_cnt; i++) {
+ EMIT(PPC_RAW_STW(bpf_to_ppc(TMP_REG), _R1, cookie_off + 4 * i));
+ EMIT(PPC_RAW_STW(bpf_to_ppc(TMP_REG), _R1, cookie_off + 4 * i + 4));
+ }
+
+ EMIT(PPC_RAW_STW(bpf_to_ppc(TMP_REG), _R1, retval_off));
+ EMIT(PPC_RAW_STW(bpf_to_ppc(TMP_REG), _R1, retval_off + 4));
+}
+
+void store_func_meta(u32 *image, struct codegen_context *ctx,
+ u64 func_meta, int func_meta_off)
+{
+ /*
+ * Store func_meta to stack: [R1 + func_meta_off] = func_meta
+ * func_meta := argument count in first byte + cookie value
+ */
+ /* Store lower word */
+ EMIT(PPC_RAW_LI(bpf_to_ppc(TMP_REG), (u32)func_meta));
+ EMIT(PPC_RAW_STW(bpf_to_ppc(TMP_REG), _R1, func_meta_off));
+
+ /* Store upper word */
+ EMIT(PPC_RAW_LI(bpf_to_ppc(TMP_REG), (u32)(func_meta >> 32)));
+ EMIT(PPC_RAW_STW(bpf_to_ppc(TMP_REG), _R1, func_meta_off + 4));
+}
+
void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
{
int i;
--
2.52.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
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