[PATCH bpf-next v3 0/4] powerpc64/bpf: Add support for bpf arena and arena atomics

[PATCH bpf-next v3 0/4] powerpc64/bpf: Add support for bpf arena and arena atomics

[Saket Kumar Bhaskar]

This patch series introduces support for the PROBE_MEM32,
bpf_addr_space_cast and PROBE_ATOMIC instructions in the powerpc BPF JIT,
facilitating the implementation of BPF arena and arena atomics.

All selftests related to bpf_arena, bpf_arena_atomic(except
load_acquire/store_release) enablement are passing:

# ./test_progs -t arena_list
#5/1     arena_list/arena_list_1:OK
#5/2     arena_list/arena_list_1000:OK
#5       arena_list:OK
Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED

# ./test_progs -t arena_htab
#4/1     arena_htab/arena_htab_llvm:OK
#4/2     arena_htab/arena_htab_asm:OK
#4       arena_htab:OK
Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED

# ./test_progs -t verifier_arena
#464/1   verifier_arena/basic_alloc1:OK
#464/2   verifier_arena/basic_alloc2:OK
#464/3   verifier_arena/basic_alloc3:OK
#464/4   verifier_arena/iter_maps1:OK
#464/5   verifier_arena/iter_maps2:OK
#464/6   verifier_arena/iter_maps3:OK
#464     verifier_arena:OK
#465/1   verifier_arena_large/big_alloc1:OK
#465/2   verifier_arena_large/big_alloc2:OK
#465     verifier_arena_large:OK
Summary: 2/8 PASSED, 0 SKIPPED, 0 FAILED

# ./test_progs -t arena_atomics
#3/1     arena_atomics/add:OK
#3/2     arena_atomics/sub:OK
#3/3     arena_atomics/and:OK
#3/4     arena_atomics/or:OK
#3/5     arena_atomics/xor:OK
#3/6     arena_atomics/cmpxchg:OK
#3/7     arena_atomics/xchg:OK
#3/8     arena_atomics/uaf:OK
#3/9     arena_atomics/load_acquire:SKIP
#3/10    arena_atomics/store_release:SKIP
#3       arena_atomics:OK (SKIP: 2/10)
Summary: 1/8 PASSED, 2 SKIPPED, 0 FAILED

Changes since v2:
* Dropped arena_spin_lock selftest fix patch from the patchset as it has
  to go via bpf-next while these changes will go via powerpc tree.

v2:https://lore.kernel.org/all/20250829165135.1273071-1-skb99@linux.ibm.com/

Changes since v1:

Addressed comments from Chris:
* Squashed introduction of bpf_jit_emit_probe_mem_store() and its usage in
  one patch.
* Defined and used PPC_RAW_RLDICL_DOT to avoid the CMPDI.
* Removed conditional statement for fixup[0] = PPC_RAW_LI(dst_reg, 0);
* Indicated this change is limited to powerpc64 in subject.

Addressed comments from Alexei:
* Removed skel->rodata->nr_cpus = get_nprocs() and its usage to get
  currently online cpus(as it needs to be updated from userspace).

Addressed comments from Hari:
* Updated the bpf jit stack layout and associated macros to accommodate
  new NVR.

v1:https://lore.kernel.org/all/20250805062747.3479221-1-skb99@linux.ibm.com/

Saket Kumar Bhaskar (4):
  powerpc64/bpf: Implement PROBE_MEM32 pseudo instructions
  powerpc64/bpf: Implement bpf_addr_space_cast instruction
  powerpc64/bpf: Introduce bpf_jit_emit_atomic_ops() to emit atomic
    instructions
  powerpc64/bpf: Implement PROBE_ATOMIC instructions

 arch/powerpc/include/asm/ppc-opcode.h |   1 +
 arch/powerpc/net/bpf_jit.h            |   6 +-
 arch/powerpc/net/bpf_jit_comp.c       |  32 +-
 arch/powerpc/net/bpf_jit_comp32.c     |   2 +-
 arch/powerpc/net/bpf_jit_comp64.c     | 401 +++++++++++++++++++-------
 5 files changed, 330 insertions(+), 112 deletions(-)

-- 
2.43.5

[PATCH bpf-next v3 1/4] powerpc64/bpf: Implement PROBE_MEM32 pseudo instructions

[Saket Kumar Bhaskar]

Add support for [LDX | STX | ST], PROBE_MEM32, [B | H | W | DW]
instructions.  They are similar to PROBE_MEM instructions with the
following differences:
- PROBE_MEM32 supports store.
- PROBE_MEM32 relies on the verifier to clear upper 32-bit of the
src/dst register
- PROBE_MEM32 adds 64-bit kern_vm_start address (which is stored in _R26
in the prologue). Due to bpf_arena constructions such _R26 + reg +
off16 access is guaranteed to be within arena virtual range, so no
address check at run-time.
- PROBE_MEM32 allows STX and ST. If they fault the store is a nop. When
LDX faults the destination register is zeroed.

To support these on powerpc, we do tmp1 = _R26 + src/dst reg and then use
tmp1 as the new src/dst register. This allows us to reuse most of the
code for normal [LDX | STX | ST].

Additionally, bpf_jit_emit_probe_mem_store() is introduced to emit
instructions for storing memory values depending on the size (byte,
halfword, word, doubleword).

Stack layout is adjusted to introduce a new NVR (_R26) and to make
BPF_PPC_STACKFRAME quadword aligned (local_tmp_var is increased by
8 bytes).

Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
---
 arch/powerpc/net/bpf_jit.h        |   5 +-
 arch/powerpc/net/bpf_jit_comp.c   |  10 +-
 arch/powerpc/net/bpf_jit_comp32.c |   2 +-
 arch/powerpc/net/bpf_jit_comp64.c | 162 ++++++++++++++++++++++++++----
 4 files changed, 155 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index 4c26912c2e3c..2d095a873305 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h
@@ -161,9 +161,10 @@ struct codegen_context {
 	unsigned int seen;
 	unsigned int idx;
 	unsigned int stack_size;
-	int b2p[MAX_BPF_JIT_REG + 2];
+	int b2p[MAX_BPF_JIT_REG + 3];
 	unsigned int exentry_idx;
 	unsigned int alt_exit_addr;
+	u64 arena_vm_start;
 };
 
 #define bpf_to_ppc(r)	(ctx->b2p[r])
@@ -201,7 +202,7 @@ int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg,
 
 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);
+			  int jmp_off, int dst_reg, u32 code);
 
 #endif
 
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index c0684733e9d6..7d070232159f 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -204,6 +204,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 
 	/* Make sure that the stack is quadword aligned. */
 	cgctx.stack_size = round_up(fp->aux->stack_depth, 16);
+	cgctx.arena_vm_start = bpf_arena_get_kern_vm_start(fp->aux->arena);
 
 	/* Scouting faux-generate pass 0 */
 	if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) {
@@ -326,7 +327,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
  */
 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)
+			  int dst_reg, u32 code)
 {
 	off_t offset;
 	unsigned long pc;
@@ -355,6 +356,9 @@ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass
 		(ctx->exentry_idx * BPF_FIXUP_LEN * 4);
 
 	fixup[0] = PPC_RAW_LI(dst_reg, 0);
+	if (BPF_CLASS(code) == BPF_ST || BPF_CLASS(code) == BPF_STX)
+		fixup[0] = PPC_RAW_NOP();
+
 	if (IS_ENABLED(CONFIG_PPC32))
 		fixup[1] = PPC_RAW_LI(dst_reg - 1, 0); /* clear higher 32-bit register too */
 
@@ -579,7 +583,7 @@ static void bpf_trampoline_setup_tail_call_cnt(u32 *image, struct codegen_contex
 {
 	if (IS_ENABLED(CONFIG_PPC64)) {
 		/* See bpf_jit_stack_tailcallcnt() */
-		int tailcallcnt_offset = 6 * 8;
+		int tailcallcnt_offset = 7 * 8;
 
 		EMIT(PPC_RAW_LL(_R3, _R1, func_frame_offset - tailcallcnt_offset));
 		EMIT(PPC_RAW_STL(_R3, _R1, -tailcallcnt_offset));
@@ -594,7 +598,7 @@ static void bpf_trampoline_restore_tail_call_cnt(u32 *image, struct codegen_cont
 {
 	if (IS_ENABLED(CONFIG_PPC64)) {
 		/* See bpf_jit_stack_tailcallcnt() */
-		int tailcallcnt_offset = 6 * 8;
+		int tailcallcnt_offset = 7 * 8;
 
 		EMIT(PPC_RAW_LL(_R3, _R1, -tailcallcnt_offset));
 		EMIT(PPC_RAW_STL(_R3, _R1, func_frame_offset - tailcallcnt_offset));
diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index 0aace304dfe1..3087e744fb25 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -1087,7 +1087,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 				}
 
 				ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, insn_idx,
-							    jmp_off, dst_reg);
+							    jmp_off, dst_reg, code);
 				if (ret)
 					return ret;
 			}
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 025524378443..569619f1b31c 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -25,18 +25,18 @@
  * with our redzone usage.
  *
  *		[	prev sp		] <-------------
- *		[   nv gpr save area	] 5*8		|
+ *		[   nv gpr save area	] 6*8		|
  *		[    tail_call_cnt	] 8		|
- *		[    local_tmp_var	] 16		|
+ *		[    local_tmp_var	] 24		|
  * fp (r31) -->	[   ebpf stack space	] upto 512	|
  *		[     frame header	] 32/112	|
  * sp (r1) --->	[    stack pointer	] --------------
  */
 
 /* for gpr non volatile registers BPG_REG_6 to 10 */
-#define BPF_PPC_STACK_SAVE	(5*8)
+#define BPF_PPC_STACK_SAVE	(6*8)
 /* for bpf JIT code internal usage */
-#define BPF_PPC_STACK_LOCALS	24
+#define BPF_PPC_STACK_LOCALS	32
 /* stack frame excluding BPF stack, ensure this is quadword aligned */
 #define BPF_PPC_STACKFRAME	(STACK_FRAME_MIN_SIZE + \
 				 BPF_PPC_STACK_LOCALS + BPF_PPC_STACK_SAVE)
@@ -44,6 +44,7 @@
 /* BPF register usage */
 #define TMP_REG_1	(MAX_BPF_JIT_REG + 0)
 #define TMP_REG_2	(MAX_BPF_JIT_REG + 1)
+#define ARENA_VM_START  (MAX_BPF_JIT_REG + 2)
 
 /* BPF to ppc register mappings */
 void bpf_jit_init_reg_mapping(struct codegen_context *ctx)
@@ -67,10 +68,12 @@ void bpf_jit_init_reg_mapping(struct codegen_context *ctx)
 	ctx->b2p[BPF_REG_AX] = _R12;
 	ctx->b2p[TMP_REG_1] = _R9;
 	ctx->b2p[TMP_REG_2] = _R10;
+	/* non volatile register for kern_vm_start address */
+	ctx->b2p[ARENA_VM_START] = _R26;
 }
 
-/* PPC NVR range -- update this if we ever use NVRs below r27 */
-#define BPF_PPC_NVR_MIN		_R27
+/* PPC NVR range -- update this if we ever use NVRs below r26 */
+#define BPF_PPC_NVR_MIN		_R26
 
 static inline bool bpf_has_stack_frame(struct codegen_context *ctx)
 {
@@ -89,9 +92,9 @@ static inline bool bpf_has_stack_frame(struct codegen_context *ctx)
  *		[	prev sp		] <-------------
  *		[	  ...       	] 		|
  * sp (r1) --->	[    stack pointer	] --------------
- *		[   nv gpr save area	] 5*8
+ *		[   nv gpr save area	] 6*8
  *		[    tail_call_cnt	] 8
- *		[    local_tmp_var	] 16
+ *		[    local_tmp_var	] 24
  *		[   unused red zone	] 224
  */
 static int bpf_jit_stack_local(struct codegen_context *ctx)
@@ -99,12 +102,12 @@ static int bpf_jit_stack_local(struct codegen_context *ctx)
 	if (bpf_has_stack_frame(ctx))
 		return STACK_FRAME_MIN_SIZE + ctx->stack_size;
 	else
-		return -(BPF_PPC_STACK_SAVE + 24);
+		return -(BPF_PPC_STACK_SAVE + 32);
 }
 
 static int bpf_jit_stack_tailcallcnt(struct codegen_context *ctx)
 {
-	return bpf_jit_stack_local(ctx) + 16;
+	return bpf_jit_stack_local(ctx) + 24;
 }
 
 static int bpf_jit_stack_offsetof(struct codegen_context *ctx, int reg)
@@ -170,10 +173,17 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
 		if (bpf_is_seen_register(ctx, bpf_to_ppc(i)))
 			EMIT(PPC_RAW_STD(bpf_to_ppc(i), _R1, bpf_jit_stack_offsetof(ctx, bpf_to_ppc(i))));
 
+	if (ctx->arena_vm_start)
+		EMIT(PPC_RAW_STD(bpf_to_ppc(ARENA_VM_START), _R1,
+				 bpf_jit_stack_offsetof(ctx, bpf_to_ppc(ARENA_VM_START))));
+
 	/* Setup frame pointer to point to the bpf stack area */
 	if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP)))
 		EMIT(PPC_RAW_ADDI(bpf_to_ppc(BPF_REG_FP), _R1,
 				STACK_FRAME_MIN_SIZE + ctx->stack_size));
+
+	if (ctx->arena_vm_start)
+		PPC_LI64(bpf_to_ppc(ARENA_VM_START), ctx->arena_vm_start);
 }
 
 static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx)
@@ -185,6 +195,10 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx
 		if (bpf_is_seen_register(ctx, bpf_to_ppc(i)))
 			EMIT(PPC_RAW_LD(bpf_to_ppc(i), _R1, bpf_jit_stack_offsetof(ctx, bpf_to_ppc(i))));
 
+	if (ctx->arena_vm_start)
+		EMIT(PPC_RAW_LD(bpf_to_ppc(ARENA_VM_START), _R1,
+				bpf_jit_stack_offsetof(ctx, bpf_to_ppc(ARENA_VM_START))));
+
 	/* Tear down our stack frame */
 	if (bpf_has_stack_frame(ctx)) {
 		EMIT(PPC_RAW_ADDI(_R1, _R1, BPF_PPC_STACKFRAME + ctx->stack_size));
@@ -396,11 +410,11 @@ void bpf_stf_barrier(void);
 asm (
 "		.global bpf_stf_barrier		;"
 "	bpf_stf_barrier:			;"
-"		std	21,-64(1)		;"
-"		std	22,-56(1)		;"
+"		std	21,-80(1)		;"
+"		std	22,-72(1)		;"
 "		sync				;"
-"		ld	21,-64(1)		;"
-"		ld	22,-56(1)		;"
+"		ld	21,-80(1)		;"
+"		ld	22,-72(1)		;"
 "		ori	31,31,0			;"
 "		.rept 14			;"
 "		b	1f			;"
@@ -409,6 +423,36 @@ asm (
 "		blr				;"
 );
 
+static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, u32 src_reg, s16 off,
+					u32 code, u32 *image)
+{
+	u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
+	u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
+
+	switch (BPF_SIZE(code)) {
+	case BPF_B:
+		EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off));
+		break;
+	case BPF_H:
+		EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off));
+		break;
+	case BPF_W:
+		EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off));
+		break;
+	case BPF_DW:
+		if (off % 4) {
+			EMIT(PPC_RAW_LI(tmp2_reg, off));
+			EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg));
+		} else {
+			EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off));
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static int emit_atomic_ld_st(const struct bpf_insn insn, struct codegen_context *ctx, u32 *image)
 {
 	u32 code = insn.code;
@@ -960,6 +1004,50 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 			}
 			break;
 
+		case BPF_STX | BPF_PROBE_MEM32 | BPF_B:
+		case BPF_STX | BPF_PROBE_MEM32 | BPF_H:
+		case BPF_STX | BPF_PROBE_MEM32 | BPF_W:
+		case BPF_STX | BPF_PROBE_MEM32 | BPF_DW:
+
+			EMIT(PPC_RAW_ADD(tmp1_reg, dst_reg, bpf_to_ppc(ARENA_VM_START)));
+
+			ret = bpf_jit_emit_probe_mem_store(ctx, src_reg, off, code, image);
+			if (ret)
+				return ret;
+
+			ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx,
+						    ctx->idx - 1, 4, -1, code);
+			if (ret)
+				return ret;
+
+			break;
+
+		case BPF_ST | BPF_PROBE_MEM32 | BPF_B:
+		case BPF_ST | BPF_PROBE_MEM32 | BPF_H:
+		case BPF_ST | BPF_PROBE_MEM32 | BPF_W:
+		case BPF_ST | BPF_PROBE_MEM32 | BPF_DW:
+
+			EMIT(PPC_RAW_ADD(tmp1_reg, dst_reg, bpf_to_ppc(ARENA_VM_START)));
+
+			if (BPF_SIZE(code) == BPF_W || BPF_SIZE(code) == BPF_DW) {
+				PPC_LI32(tmp2_reg, imm);
+				src_reg = tmp2_reg;
+			} else {
+				EMIT(PPC_RAW_LI(tmp2_reg, imm));
+				src_reg = tmp2_reg;
+			}
+
+			ret = bpf_jit_emit_probe_mem_store(ctx, src_reg, off, code, image);
+			if (ret)
+				return ret;
+
+			ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx,
+						    ctx->idx - 1, 4, -1, code);
+			if (ret)
+				return ret;
+
+			break;
+
 		/*
 		 * BPF_STX ATOMIC (atomic ops)
 		 */
@@ -1112,9 +1200,10 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 				 * Check if 'off' is word aligned for BPF_DW, because
 				 * we might generate two instructions.
 				 */
-				if ((BPF_SIZE(code) == BPF_DW ||
-				    (BPF_SIZE(code) == BPF_B && BPF_MODE(code) == BPF_PROBE_MEMSX)) &&
-						(off & 3))
+				if ((BPF_SIZE(code) == BPF_DW && (off & 3)) ||
+				    (BPF_SIZE(code) == BPF_B &&
+				     BPF_MODE(code) == BPF_PROBE_MEMSX) ||
+				    (BPF_SIZE(code) == BPF_B && BPF_MODE(code) == BPF_MEMSX))
 					PPC_JMP((ctx->idx + 3) * 4);
 				else
 					PPC_JMP((ctx->idx + 2) * 4);
@@ -1160,12 +1249,49 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 
 			if (BPF_MODE(code) == BPF_PROBE_MEM) {
 				ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx,
-							    ctx->idx - 1, 4, dst_reg);
+							    ctx->idx - 1, 4, dst_reg, code);
 				if (ret)
 					return ret;
 			}
 			break;
 
+		/* dst = *(u64 *)(ul) (src + ARENA_VM_START + off) */
+		case BPF_LDX | BPF_PROBE_MEM32 | BPF_B:
+		case BPF_LDX | BPF_PROBE_MEM32 | BPF_H:
+		case BPF_LDX | BPF_PROBE_MEM32 | BPF_W:
+		case BPF_LDX | BPF_PROBE_MEM32 | BPF_DW:
+
+			EMIT(PPC_RAW_ADD(tmp1_reg, src_reg, bpf_to_ppc(ARENA_VM_START)));
+
+			switch (size) {
+			case BPF_B:
+				EMIT(PPC_RAW_LBZ(dst_reg, tmp1_reg, off));
+				break;
+			case BPF_H:
+				EMIT(PPC_RAW_LHZ(dst_reg, tmp1_reg, off));
+				break;
+			case BPF_W:
+				EMIT(PPC_RAW_LWZ(dst_reg, tmp1_reg, off));
+				break;
+			case BPF_DW:
+				if (off % 4) {
+					EMIT(PPC_RAW_LI(tmp2_reg, off));
+					EMIT(PPC_RAW_LDX(dst_reg, tmp1_reg, tmp2_reg));
+				} else {
+					EMIT(PPC_RAW_LD(dst_reg, tmp1_reg, off));
+				}
+				break;
+			}
+
+			if (size != BPF_DW && insn_is_zext(&insn[i + 1]))
+				addrs[++i] = ctx->idx * 4;
+
+			ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx,
+						    ctx->idx - 1, 4, dst_reg, code);
+			if (ret)
+				return ret;
+			break;
+
 		/*
 		 * Doubleword load
 		 * 16 byte instruction that uses two 'struct bpf_insn'
-- 
2.43.5

[PATCH bpf-next v3 2/4] powerpc64/bpf: Implement bpf_addr_space_cast instruction

[Saket Kumar Bhaskar]

LLVM generates bpf_addr_space_cast instruction while translating
pointers between native (zero) address space and
__attribute__((address_space(N))). The addr_space=0 is reserved as
bpf_arena address space.

rY = addr_space_cast(rX, 0, 1) is processed by the verifier and
converted to normal 32-bit move: wX = wY.

rY = addr_space_cast(rX, 1, 0) : used to convert a bpf arena pointer to
a pointer in the userspace vma. This has to be converted by the JIT.

PPC_RAW_RLDICL_DOT, a variant of PPC_RAW_RLDICL is introduced to set
condition register as well.

Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
---
 arch/powerpc/include/asm/ppc-opcode.h |  1 +
 arch/powerpc/net/bpf_jit.h            |  1 +
 arch/powerpc/net/bpf_jit_comp.c       |  6 ++++++
 arch/powerpc/net/bpf_jit_comp64.c     | 10 ++++++++++
 4 files changed, 18 insertions(+)

diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 8053b24afc39..55ca49d18319 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -571,6 +571,7 @@
 					(0x54000001 | ___PPC_RA(d) | ___PPC_RS(a) | __PPC_SH(i) | __PPC_MB(mb) | __PPC_ME(me))
 #define PPC_RAW_RLWIMI(d, a, i, mb, me) (0x50000000 | ___PPC_RA(d) | ___PPC_RS(a) | __PPC_SH(i) | __PPC_MB(mb) | __PPC_ME(me))
 #define PPC_RAW_RLDICL(d, a, i, mb)     (0x78000000 | ___PPC_RA(d) | ___PPC_RS(a) | __PPC_SH64(i) | __PPC_MB64(mb))
+#define PPC_RAW_RLDICL_DOT(d, a, i, mb) (0x78000000 | ___PPC_RA(d) | ___PPC_RS(a) | __PPC_SH64(i) | __PPC_MB64(mb) | 0x1)
 #define PPC_RAW_RLDICR(d, a, i, me)     (0x78000004 | ___PPC_RA(d) | ___PPC_RS(a) | __PPC_SH64(i) | __PPC_ME64(me))
 
 /* slwi = rlwinm Rx, Ry, n, 0, 31-n */
diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index 2d095a873305..748e30e8b5b4 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h
@@ -165,6 +165,7 @@ struct codegen_context {
 	unsigned int exentry_idx;
 	unsigned int alt_exit_addr;
 	u64 arena_vm_start;
+	u64 user_vm_start;
 };
 
 #define bpf_to_ppc(r)	(ctx->b2p[r])
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 7d070232159f..cfa84cab0a18 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -205,6 +205,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 	/* Make sure that the stack is quadword aligned. */
 	cgctx.stack_size = round_up(fp->aux->stack_depth, 16);
 	cgctx.arena_vm_start = bpf_arena_get_kern_vm_start(fp->aux->arena);
+	cgctx.user_vm_start = bpf_arena_get_user_vm_start(fp->aux->arena);
 
 	/* Scouting faux-generate pass 0 */
 	if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) {
@@ -439,6 +440,11 @@ bool bpf_jit_supports_kfunc_call(void)
 	return true;
 }
 
+bool bpf_jit_supports_arena(void)
+{
+	return IS_ENABLED(CONFIG_PPC64);
+}
+
 bool bpf_jit_supports_far_kfunc_call(void)
 {
 	return IS_ENABLED(CONFIG_PPC64);
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 569619f1b31c..76efb47f02a6 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -812,6 +812,16 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 		 */
 		case BPF_ALU | BPF_MOV | BPF_X: /* (u32) dst = src */
 		case BPF_ALU64 | BPF_MOV | BPF_X: /* dst = src */
+
+			if (insn_is_cast_user(&insn[i])) {
+				EMIT(PPC_RAW_RLDICL_DOT(tmp1_reg, src_reg, 0, 32));
+				PPC_LI64(dst_reg, (ctx->user_vm_start & 0xffffffff00000000UL));
+				PPC_BCC_SHORT(COND_EQ, (ctx->idx + 2) * 4);
+				EMIT(PPC_RAW_OR(tmp1_reg, dst_reg, tmp1_reg));
+				EMIT(PPC_RAW_MR(dst_reg, tmp1_reg));
+				break;
+			}
+
 			if (imm == 1) {
 				/* special mov32 for zext */
 				EMIT(PPC_RAW_RLWINM(dst_reg, dst_reg, 0, 0, 31));
-- 
2.43.5

[PATCH bpf-next v3 3/4] powerpc64/bpf: Introduce bpf_jit_emit_atomic_ops() to emit atomic instructions

[Saket Kumar Bhaskar]

The existing code for emitting bpf atomic instruction sequences for
atomic operations such as XCHG, CMPXCHG, ADD, AND, OR, and XOR has been
refactored into a reusable function, bpf_jit_emit_ppc_atomic_op().
It also computes the jump offset and tracks the instruction index for jited
LDARX/LWARX to be used in case it causes a fault.

Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
---
 arch/powerpc/net/bpf_jit_comp64.c | 203 +++++++++++++++++-------------
 1 file changed, 115 insertions(+), 88 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 76efb47f02a6..cb4d1e954961 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -423,6 +423,111 @@ asm (
 "		blr				;"
 );
 
+static int bpf_jit_emit_atomic_ops(u32 *image, struct codegen_context *ctx,
+				   const struct bpf_insn *insn, u32 *jmp_off,
+				   u32 *tmp_idx, u32 *addrp)
+{
+	u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
+	u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
+	u32 size = BPF_SIZE(insn->code);
+	u32 src_reg = bpf_to_ppc(insn->src_reg);
+	u32 dst_reg = bpf_to_ppc(insn->dst_reg);
+	s32 imm = insn->imm;
+
+	u32 save_reg = tmp2_reg;
+	u32 ret_reg = src_reg;
+	u32 fixup_idx;
+
+	/* Get offset into TMP_REG_1 */
+	EMIT(PPC_RAW_LI(tmp1_reg, insn->off));
+       /*
+	* Enforce full ordering for operations with BPF_FETCH by emitting a 'sync'
+	* before and after the operation.
+	*
+	* This is a requirement in the Linux Kernel Memory Model.
+	* See __cmpxchg_u64() in asm/cmpxchg.h as an example.
+	*/
+	if ((imm & BPF_FETCH) && IS_ENABLED(CONFIG_SMP))
+		EMIT(PPC_RAW_SYNC());
+
+	*tmp_idx = ctx->idx;
+
+	/* load value from memory into TMP_REG_2 */
+	if (size == BPF_DW)
+		EMIT(PPC_RAW_LDARX(tmp2_reg, tmp1_reg, dst_reg, 0));
+	else
+		EMIT(PPC_RAW_LWARX(tmp2_reg, tmp1_reg, dst_reg, 0));
+	/* Save old value in _R0 */
+	if (imm & BPF_FETCH)
+		EMIT(PPC_RAW_MR(_R0, tmp2_reg));
+
+	switch (imm) {
+	case BPF_ADD:
+	case BPF_ADD | BPF_FETCH:
+		EMIT(PPC_RAW_ADD(tmp2_reg, tmp2_reg, src_reg));
+		break;
+	case BPF_AND:
+	case BPF_AND | BPF_FETCH:
+		EMIT(PPC_RAW_AND(tmp2_reg, tmp2_reg, src_reg));
+		break;
+	case BPF_OR:
+	case BPF_OR | BPF_FETCH:
+		EMIT(PPC_RAW_OR(tmp2_reg, tmp2_reg, src_reg));
+		break;
+	case BPF_XOR:
+	case BPF_XOR | BPF_FETCH:
+		EMIT(PPC_RAW_XOR(tmp2_reg, tmp2_reg, src_reg));
+		break;
+	case BPF_CMPXCHG:
+	       /*
+		* Return old value in BPF_REG_0 for BPF_CMPXCHG &
+		* in src_reg for other cases.
+		*/
+		ret_reg = bpf_to_ppc(BPF_REG_0);
+
+		/* Compare with old value in BPF_R0 */
+		if (size == BPF_DW)
+			EMIT(PPC_RAW_CMPD(bpf_to_ppc(BPF_REG_0), tmp2_reg));
+		else
+			EMIT(PPC_RAW_CMPW(bpf_to_ppc(BPF_REG_0), tmp2_reg));
+		/* Don't set if different from old value */
+		PPC_BCC_SHORT(COND_NE, (ctx->idx + 3) * 4);
+		fallthrough;
+	case BPF_XCHG:
+		save_reg = src_reg;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	/* store new value */
+	if (size == BPF_DW)
+		EMIT(PPC_RAW_STDCX(save_reg, tmp1_reg, dst_reg));
+	else
+		EMIT(PPC_RAW_STWCX(save_reg, tmp1_reg, dst_reg));
+	/* we're done if this succeeded */
+	PPC_BCC_SHORT(COND_NE, *tmp_idx * 4);
+	fixup_idx = ctx->idx;
+
+	if (imm & BPF_FETCH) {
+		/* Emit 'sync' to enforce full ordering */
+		if (IS_ENABLED(CONFIG_SMP))
+			EMIT(PPC_RAW_SYNC());
+		EMIT(PPC_RAW_MR(ret_reg, _R0));
+		/*
+		 * Skip unnecessary zero-extension for 32-bit cmpxchg.
+		 * For context, see commit 39491867ace5.
+		 */
+		if (size != BPF_DW && imm == BPF_CMPXCHG &&
+		    insn_is_zext(insn + 1))
+			*addrp = ctx->idx * 4;
+	}
+
+	*jmp_off = (fixup_idx - *tmp_idx) * 4;
+
+	return 0;
+}
+
 static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, u32 src_reg, s16 off,
 					u32 code, u32 *image)
 {
@@ -538,7 +643,6 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 		u32 size = BPF_SIZE(code);
 		u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
 		u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
-		u32 save_reg, ret_reg;
 		s16 off = insn[i].off;
 		s32 imm = insn[i].imm;
 		bool func_addr_fixed;
@@ -546,6 +650,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 		u64 imm64;
 		u32 true_cond;
 		u32 tmp_idx;
+		u32 jmp_off;
 
 		/*
 		 * addrs[] maps a BPF bytecode address into a real offset from
@@ -1080,93 +1185,15 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 				return -EOPNOTSUPP;
 			}
 
-			save_reg = tmp2_reg;
-			ret_reg = src_reg;
-
-			/* Get offset into TMP_REG_1 */
-			EMIT(PPC_RAW_LI(tmp1_reg, off));
-			/*
-			 * Enforce full ordering for operations with BPF_FETCH by emitting a 'sync'
-			 * before and after the operation.
-			 *
-			 * This is a requirement in the Linux Kernel Memory Model.
-			 * See __cmpxchg_u64() in asm/cmpxchg.h as an example.
-			 */
-			if ((imm & BPF_FETCH) && IS_ENABLED(CONFIG_SMP))
-				EMIT(PPC_RAW_SYNC());
-			tmp_idx = ctx->idx * 4;
-			/* load value from memory into TMP_REG_2 */
-			if (size == BPF_DW)
-				EMIT(PPC_RAW_LDARX(tmp2_reg, tmp1_reg, dst_reg, 0));
-			else
-				EMIT(PPC_RAW_LWARX(tmp2_reg, tmp1_reg, dst_reg, 0));
-
-			/* Save old value in _R0 */
-			if (imm & BPF_FETCH)
-				EMIT(PPC_RAW_MR(_R0, tmp2_reg));
-
-			switch (imm) {
-			case BPF_ADD:
-			case BPF_ADD | BPF_FETCH:
-				EMIT(PPC_RAW_ADD(tmp2_reg, tmp2_reg, src_reg));
-				break;
-			case BPF_AND:
-			case BPF_AND | BPF_FETCH:
-				EMIT(PPC_RAW_AND(tmp2_reg, tmp2_reg, src_reg));
-				break;
-			case BPF_OR:
-			case BPF_OR | BPF_FETCH:
-				EMIT(PPC_RAW_OR(tmp2_reg, tmp2_reg, src_reg));
-				break;
-			case BPF_XOR:
-			case BPF_XOR | BPF_FETCH:
-				EMIT(PPC_RAW_XOR(tmp2_reg, tmp2_reg, src_reg));
-				break;
-			case BPF_CMPXCHG:
-				/*
-				 * Return old value in BPF_REG_0 for BPF_CMPXCHG &
-				 * in src_reg for other cases.
-				 */
-				ret_reg = bpf_to_ppc(BPF_REG_0);
-
-				/* Compare with old value in BPF_R0 */
-				if (size == BPF_DW)
-					EMIT(PPC_RAW_CMPD(bpf_to_ppc(BPF_REG_0), tmp2_reg));
-				else
-					EMIT(PPC_RAW_CMPW(bpf_to_ppc(BPF_REG_0), tmp2_reg));
-				/* Don't set if different from old value */
-				PPC_BCC_SHORT(COND_NE, (ctx->idx + 3) * 4);
-				fallthrough;
-			case BPF_XCHG:
-				save_reg = src_reg;
-				break;
-			default:
-				pr_err_ratelimited(
-					"eBPF filter atomic op code %02x (@%d) unsupported\n",
-					code, i);
-				return -EOPNOTSUPP;
-			}
-
-			/* store new value */
-			if (size == BPF_DW)
-				EMIT(PPC_RAW_STDCX(save_reg, tmp1_reg, dst_reg));
-			else
-				EMIT(PPC_RAW_STWCX(save_reg, tmp1_reg, dst_reg));
-			/* we're done if this succeeded */
-			PPC_BCC_SHORT(COND_NE, tmp_idx);
-
-			if (imm & BPF_FETCH) {
-				/* Emit 'sync' to enforce full ordering */
-				if (IS_ENABLED(CONFIG_SMP))
-					EMIT(PPC_RAW_SYNC());
-				EMIT(PPC_RAW_MR(ret_reg, _R0));
-				/*
-				 * Skip unnecessary zero-extension for 32-bit cmpxchg.
-				 * For context, see commit 39491867ace5.
-				 */
-				if (size != BPF_DW && imm == BPF_CMPXCHG &&
-				    insn_is_zext(&insn[i + 1]))
-					addrs[++i] = ctx->idx * 4;
+			ret = bpf_jit_emit_atomic_ops(image, ctx, &insn[i],
+						      &jmp_off, &tmp_idx, &addrs[i + 1]);
+			if (ret) {
+				if (ret == -EOPNOTSUPP) {
+					pr_err_ratelimited(
+						"eBPF filter atomic op code %02x (@%d) unsupported\n",
+						code, i);
+				}
+				return ret;
 			}
 			break;
 
-- 
2.43.5

[PATCH bpf-next v3 4/4] powerpc64/bpf: Implement PROBE_ATOMIC instructions

[Saket Kumar Bhaskar]

powerpc supports BPF atomic operations using a loop around
Load-And-Reserve(LDARX/LWARX) and Store-Conditional(STDCX/STWCX)
instructions gated by sync instructions to enforce full ordering.

To implement arena_atomics, arena vm start address is added to the
dst_reg to be used for both the LDARX/LWARX and STDCX/STWCX instructions.
Further, an exception table entry is added for LDARX/LWARX
instruction to land after the loop on fault. At the end of sequence,
dst_reg is restored by subtracting arena vm start address.

bpf_jit_supports_insn() is introduced to selectively enable instruction
support as in other architectures like x86 and arm64.

Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
---
 arch/powerpc/net/bpf_jit_comp.c   | 16 ++++++++++++++++
 arch/powerpc/net/bpf_jit_comp64.c | 26 ++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index cfa84cab0a18..88ad5ba7b87f 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -450,6 +450,22 @@ bool bpf_jit_supports_far_kfunc_call(void)
 	return IS_ENABLED(CONFIG_PPC64);
 }
 
+bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena)
+{
+	if (!in_arena)
+		return true;
+	switch (insn->code) {
+	case BPF_STX | BPF_ATOMIC | BPF_H:
+	case BPF_STX | BPF_ATOMIC | BPF_B:
+	case BPF_STX | BPF_ATOMIC | BPF_W:
+	case BPF_STX | BPF_ATOMIC | BPF_DW:
+		if (bpf_atomic_is_load_store(insn))
+			return false;
+		return IS_ENABLED(CONFIG_PPC64);
+	}
+	return true;
+}
+
 void *arch_alloc_bpf_trampoline(unsigned int size)
 {
 	return bpf_prog_pack_alloc(size, bpf_jit_fill_ill_insns);
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index cb4d1e954961..1fe37128c876 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -1163,6 +1163,32 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 
 			break;
 
+		/*
+		 * BPF_STX PROBE_ATOMIC (arena atomic ops)
+		 */
+		case BPF_STX | BPF_PROBE_ATOMIC | BPF_W:
+		case BPF_STX | BPF_PROBE_ATOMIC | BPF_DW:
+			EMIT(PPC_RAW_ADD(dst_reg, dst_reg, bpf_to_ppc(ARENA_VM_START)));
+			ret = bpf_jit_emit_atomic_ops(image, ctx, &insn[i],
+						      &jmp_off, &tmp_idx, &addrs[i + 1]);
+			if (ret) {
+				if (ret == -EOPNOTSUPP) {
+					pr_err_ratelimited(
+						"eBPF filter atomic op code %02x (@%d) unsupported\n",
+						code, i);
+				}
+				return ret;
+			}
+			/* LDARX/LWARX should land here on exception. */
+			ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx,
+						    tmp_idx, jmp_off, dst_reg, code);
+			if (ret)
+				return ret;
+
+			/* Retrieve the dst_reg */
+			EMIT(PPC_RAW_SUB(dst_reg, dst_reg, bpf_to_ppc(ARENA_VM_START)));
+			break;
+
 		/*
 		 * BPF_STX ATOMIC (atomic ops)
 		 */
-- 
2.43.5

Re: [PATCH bpf-next v3 0/4] powerpc64/bpf: Add support for bpf arena and arena atomics

[Madhavan Srinivasan]

On Thu, 04 Sep 2025 15:38:31 +0530, Saket Kumar Bhaskar wrote:
> This patch series introduces support for the PROBE_MEM32,
> bpf_addr_space_cast and PROBE_ATOMIC instructions in the powerpc BPF JIT,
> facilitating the implementation of BPF arena and arena atomics.
> 
> All selftests related to bpf_arena, bpf_arena_atomic(except
> load_acquire/store_release) enablement are passing:
> 
> [...]

Applied to powerpc/next.

[1/4] powerpc64/bpf: Implement PROBE_MEM32 pseudo instructions
      https://git.kernel.org/powerpc/c/47c7f3b7038787ee42cb9ed69825e6790dba9410
[2/4] powerpc64/bpf: Implement bpf_addr_space_cast instruction
      https://git.kernel.org/powerpc/c/a2485d06cad3741303b9414e44f9b6d76d3713f2
[3/4] powerpc64/bpf: Introduce bpf_jit_emit_atomic_ops() to emit atomic instructions
      https://git.kernel.org/powerpc/c/45ed2e8b0591eb6211d79f436f76c3af31e626af
[4/4] powerpc64/bpf: Implement PROBE_ATOMIC instructions
      https://git.kernel.org/powerpc/c/0c1da35b0188dd565cec907a16cb5d1bd425e0e4

Thanks