[PATCH v2 1/3] powerpc64/bpf: Implement fsession support

[PATCH v2 1/3] powerpc64/bpf: Implement fsession support

[adubey]

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/20260220063933.196141-1-hbathini@linux.ibm.com

v1->v2:
  No change since v1

[v1]: https://lore.kernel.org/bpf/20260216155310.38457-1-adubey@linux.ibm.com

Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
---
 arch/powerpc/net/bpf_jit.h        |  4 +-
 arch/powerpc/net/bpf_jit_comp.c   | 69 ++++++++++++++++++++++++++-----
 arch/powerpc/net/bpf_jit_comp64.c | 25 +++++++++++
 3 files changed, 87 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index a232f3fb73be..f32de8704d4d 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h
@@ -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);
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 08c992436ace..6d334c0c3d85 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -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 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          ]
 	 *                              [ ...               ]
@@ -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 egs */
 	regs_off = bpf_frame_size;
 	bpf_frame_size += nr_regs * SZL;
 
@@ -990,9 +1006,9 @@ 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));
@@ -1006,10 +1022,28 @@ 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);
@@ -1071,12 +1105,27 @@ 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 */
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 17aec341f5eb..1e2ac6c4f331 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

[PATCH v2 2/3] selftest/bpf: Enable get_func_args and get_func_ip tests on powerpc64

[adubey]

From: Abhishek Dubey <adubey@linux.ibm.com>

Allow get_func_args, 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

v1->v2:
  Resolve merge conflict

[v1]: https://lore.kernel.org/bpf/20260216155310.38457-1-adubey@linux.ibm.com

Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
---
 tools/testing/selftests/bpf/progs/get_func_args_test.c | 3 ++-
 tools/testing/selftests/bpf/progs/get_func_ip_test.c   | 3 ++-
 2 files changed, 4 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 075a1180ec26..1fe1fb0548ea 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 +167,8 @@ int BPF_PROG(tp_test2)
 }
 
 __u64 test7_result = 0;
-#if defined(bpf_target_x86) || defined(bpf_target_arm64) || defined(bpf_target_riscv)
+#if defined(bpf_target_x86) || defined(bpf_target_arm64) ||	\
+	defined(bpf_target_riscv) || 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 45eaa54d1ac7..be6b1a073b11 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 +106,8 @@ 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) || defined(bpf_target_riscv)
+#if defined(bpf_target_x86) || defined(bpf_target_arm64) ||	\
+	defined(bpf_target_riscv) || defined(bpf_target_powerpc64)
 SEC("fsession/bpf_fentry_test1")
 int BPF_PROG(test9, int a)
 {
-- 
2.52.0

[PATCH v2 3/3] powerpc32/bpf: Add fsession support

[adubey]

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.

v1->v2:
  No change since v1

[v1]: https://lore.kernel.org/bpf/20260216155310.38457-1-adubey@linux.ibm.com

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 6d334c0c3d85..8e6bfba37a67 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -542,7 +542,13 @@ 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

Re: [PATCH v2 1/3] powerpc64/bpf: Implement fsession support

[Venkat]

> On 26 Feb 2026, at 9:42 AM, adubey@linux.ibm.com wrote:
> 
> 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/20260220063933.196141-1-hbathini@linux.ibm.com
> 
> v1->v2:
>  No change since v1
> 
> [v1]: https://lore.kernel.org/bpf/20260216155310.38457-1-adubey@linux.ibm.com
> 
> Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>

Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>

> ---
> arch/powerpc/net/bpf_jit.h        |  4 +-
> arch/powerpc/net/bpf_jit_comp.c   | 69 ++++++++++++++++++++++++++-----
> arch/powerpc/net/bpf_jit_comp64.c | 25 +++++++++++
> 3 files changed, 87 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
> index a232f3fb73be..f32de8704d4d 100644
> --- a/arch/powerpc/net/bpf_jit.h
> +++ b/arch/powerpc/net/bpf_jit.h
> @@ -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);
> diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
> index 08c992436ace..6d334c0c3d85 100644
> --- a/arch/powerpc/net/bpf_jit_comp.c
> +++ b/arch/powerpc/net/bpf_jit_comp.c
> @@ -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 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          ]
> *                              [ ...               ]
> @@ -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 egs */
> regs_off = bpf_frame_size;
> bpf_frame_size += nr_regs * SZL;
> 
> @@ -990,9 +1006,9 @@ 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));
> @@ -1006,10 +1022,28 @@ 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);
> @@ -1071,12 +1105,27 @@ 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 */
> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
> index 17aec341f5eb..1e2ac6c4f331 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
> 

Re: [PATCH v2 2/3] selftest/bpf: Enable get_func_args and get_func_ip tests on powerpc64

[Venkat]

> On 26 Feb 2026, at 9:42 AM, adubey@linux.ibm.com wrote:
> 
> From: Abhishek Dubey <adubey@linux.ibm.com>
> 
> Allow get_func_args, 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
> 
> v1->v2:
>  Resolve merge conflict
> 
> [v1]: https://lore.kernel.org/bpf/20260216155310.38457-1-adubey@linux.ibm.com
> 
> Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>

./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


Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>

Regards,
Venkat.
> ---
> tools/testing/selftests/bpf/progs/get_func_args_test.c | 3 ++-
> tools/testing/selftests/bpf/progs/get_func_ip_test.c   | 3 ++-
> 2 files changed, 4 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 075a1180ec26..1fe1fb0548ea 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 +167,8 @@ int BPF_PROG(tp_test2)
> }
> 
> __u64 test7_result = 0;
> -#if defined(bpf_target_x86) || defined(bpf_target_arm64) || defined(bpf_target_riscv)
> +#if defined(bpf_target_x86) || defined(bpf_target_arm64) || \
> + defined(bpf_target_riscv) || 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 45eaa54d1ac7..be6b1a073b11 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 +106,8 @@ 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) || defined(bpf_target_riscv)
> +#if defined(bpf_target_x86) || defined(bpf_target_arm64) || \
> + defined(bpf_target_riscv) || defined(bpf_target_powerpc64)
> SEC("fsession/bpf_fentry_test1")
> int BPF_PROG(test9, int a)
> {
> -- 
> 2.52.0
>