From: Yonghong Song <yonghong.song@linux.dev>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"Jose E . Marchesi" <jose.marchesi@oracle.com>,
kernel-team@fb.com, Martin KaFai Lau <martin.lau@kernel.org>
Subject: [PATCH bpf-next v6 05/17] bpf: Introduce bpf register BPF_REG_PARAMS
Date: Sun, 19 Apr 2026 09:33:42 -0700 [thread overview]
Message-ID: <20260419163342.733840-1-yonghong.song@linux.dev> (raw)
In-Reply-To: <20260419163316.731019-1-yonghong.song@linux.dev>
Introduce BPF_REG_PARAMS as a dedicated BPF register for stack
argument accesses. It occupies the BPF register number 11 (R11),
which is used as the base pointer for the stack argument area,
keeping it separate from the R10-based (BPF_REG_FP) program stack.
The kernel-internal hidden register BPF_REG_AX previously occupied
slot 11 (MAX_BPF_REG). With BPF_REG_PARAMS taking that slot,
BPF_REG_AX moves to slot 12 and MAX_BPF_EXT_REG increases
accordingly.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
include/linux/filter.h | 5 +-
kernel/bpf/core.c | 4 +-
.../selftests/bpf/prog_tests/ctx_rewrite.c | 14 ++--
.../bpf/progs/verifier_bpf_fastcall.c | 24 +++----
.../selftests/bpf/progs/verifier_may_goto_1.c | 12 ++--
.../selftests/bpf/progs/verifier_sdiv.c | 64 +++++++++----------
6 files changed, 62 insertions(+), 61 deletions(-)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 1ec6d5ba64cc..b77d0b06db6e 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -58,8 +58,9 @@ struct ctl_table_header;
#define BPF_REG_H BPF_REG_9 /* hlen, callee-saved */
/* Kernel hidden auxiliary/helper register. */
-#define BPF_REG_AX MAX_BPF_REG
-#define MAX_BPF_EXT_REG (MAX_BPF_REG + 1)
+#define BPF_REG_PARAMS MAX_BPF_REG
+#define BPF_REG_AX (MAX_BPF_REG + 1)
+#define MAX_BPF_EXT_REG (MAX_BPF_REG + 2)
#define MAX_BPF_JIT_REG MAX_BPF_EXT_REG
/* unused opcode to mark special call to bpf_tail_call() helper */
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 8b018ff48875..ae10b9ca018d 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1299,8 +1299,8 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from,
u32 imm_rnd = get_random_u32();
s16 off;
- BUILD_BUG_ON(BPF_REG_AX + 1 != MAX_BPF_JIT_REG);
- BUILD_BUG_ON(MAX_BPF_REG + 1 != MAX_BPF_JIT_REG);
+ BUILD_BUG_ON(BPF_REG_PARAMS + 2 != MAX_BPF_JIT_REG);
+ BUILD_BUG_ON(BPF_REG_AX + 1 != MAX_BPF_JIT_REG);
/* Constraints on AX register:
*
diff --git a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
index 469e92869523..83d870e32239 100644
--- a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
+++ b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
@@ -69,19 +69,19 @@ static struct test_case test_cases[] = {
#if defined(__x86_64__) || defined(__aarch64__)
{
N(SCHED_CLS, struct __sk_buff, tstamp),
- .read = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
- "if w11 & 0x4 goto pc+1;"
+ .read = "r12 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
+ "if w12 & 0x4 goto pc+1;"
"goto pc+4;"
- "if w11 & 0x3 goto pc+1;"
+ "if w12 & 0x3 goto pc+1;"
"goto pc+2;"
"$dst = 0;"
"goto pc+1;"
"$dst = *(u64 *)($ctx + sk_buff::tstamp);",
- .write = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
- "if w11 & 0x4 goto pc+1;"
+ .write = "r12 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
+ "if w12 & 0x4 goto pc+1;"
"goto pc+2;"
- "w11 &= -4;"
- "*(u8 *)($ctx + sk_buff::__mono_tc_offset) = r11;"
+ "w12 &= -4;"
+ "*(u8 *)($ctx + sk_buff::__mono_tc_offset) = r12;"
"*(u64 *)($ctx + sk_buff::tstamp) = $src;",
},
#endif
diff --git a/tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c b/tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c
index fb4fa465d67c..0d9e167555b5 100644
--- a/tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c
+++ b/tools/testing/selftests/bpf/progs/verifier_bpf_fastcall.c
@@ -630,13 +630,13 @@ __xlated("...")
__xlated("4: r0 = &(void __percpu *)(r0)")
__xlated("...")
/* may_goto expansion starts */
-__xlated("6: r11 = *(u64 *)(r10 -24)")
-__xlated("7: if r11 == 0x0 goto pc+6")
-__xlated("8: r11 -= 1")
-__xlated("9: if r11 != 0x0 goto pc+2")
-__xlated("10: r11 = -24")
+__xlated("6: r12 = *(u64 *)(r10 -24)")
+__xlated("7: if r12 == 0x0 goto pc+6")
+__xlated("8: r12 -= 1")
+__xlated("9: if r12 != 0x0 goto pc+2")
+__xlated("10: r12 = -24")
__xlated("11: call unknown")
-__xlated("12: *(u64 *)(r10 -24) = r11")
+__xlated("12: *(u64 *)(r10 -24) = r12")
/* may_goto expansion ends */
__xlated("13: *(u64 *)(r10 -8) = r1")
__xlated("14: exit")
@@ -668,13 +668,13 @@ __xlated("1: *(u64 *)(r10 -16) =")
__xlated("2: r1 = 1")
__xlated("3: call bpf_get_smp_processor_id")
/* may_goto expansion starts */
-__xlated("4: r11 = *(u64 *)(r10 -24)")
-__xlated("5: if r11 == 0x0 goto pc+6")
-__xlated("6: r11 -= 1")
-__xlated("7: if r11 != 0x0 goto pc+2")
-__xlated("8: r11 = -24")
+__xlated("4: r12 = *(u64 *)(r10 -24)")
+__xlated("5: if r12 == 0x0 goto pc+6")
+__xlated("6: r12 -= 1")
+__xlated("7: if r12 != 0x0 goto pc+2")
+__xlated("8: r12 = -24")
__xlated("9: call unknown")
-__xlated("10: *(u64 *)(r10 -24) = r11")
+__xlated("10: *(u64 *)(r10 -24) = r12")
/* may_goto expansion ends */
__xlated("11: *(u64 *)(r10 -8) = r1")
__xlated("12: exit")
diff --git a/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c b/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c
index 6d1edaef9213..4bdf4256a41e 100644
--- a/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c
+++ b/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c
@@ -81,13 +81,13 @@ __arch_s390x
__arch_arm64
__xlated("0: *(u64 *)(r10 -16) = 65535")
__xlated("1: *(u64 *)(r10 -8) = 0")
-__xlated("2: r11 = *(u64 *)(r10 -16)")
-__xlated("3: if r11 == 0x0 goto pc+6")
-__xlated("4: r11 -= 1")
-__xlated("5: if r11 != 0x0 goto pc+2")
-__xlated("6: r11 = -16")
+__xlated("2: r12 = *(u64 *)(r10 -16)")
+__xlated("3: if r12 == 0x0 goto pc+6")
+__xlated("4: r12 -= 1")
+__xlated("5: if r12 != 0x0 goto pc+2")
+__xlated("6: r12 = -16")
__xlated("7: call unknown")
-__xlated("8: *(u64 *)(r10 -16) = r11")
+__xlated("8: *(u64 *)(r10 -16) = r12")
__xlated("9: r0 = 1")
__xlated("10: r0 = 2")
__xlated("11: exit")
diff --git a/tools/testing/selftests/bpf/progs/verifier_sdiv.c b/tools/testing/selftests/bpf/progs/verifier_sdiv.c
index fd59d57e8e37..95f3239ce228 100644
--- a/tools/testing/selftests/bpf/progs/verifier_sdiv.c
+++ b/tools/testing/selftests/bpf/progs/verifier_sdiv.c
@@ -778,10 +778,10 @@ __arch_x86_64
__xlated("0: r2 = 0x8000000000000000")
__xlated("2: r3 = -1")
__xlated("3: r4 = r2")
-__xlated("4: r11 = r3")
-__xlated("5: r11 += 1")
-__xlated("6: if r11 > 0x1 goto pc+4")
-__xlated("7: if r11 == 0x0 goto pc+1")
+__xlated("4: r12 = r3")
+__xlated("5: r12 += 1")
+__xlated("6: if r12 > 0x1 goto pc+4")
+__xlated("7: if r12 == 0x0 goto pc+1")
__xlated("8: r2 = 0")
__xlated("9: r2 = -r2")
__xlated("10: goto pc+1")
@@ -812,10 +812,10 @@ __success __retval(-5)
__arch_x86_64
__xlated("0: r2 = 5")
__xlated("1: r3 = -1")
-__xlated("2: r11 = r3")
-__xlated("3: r11 += 1")
-__xlated("4: if r11 > 0x1 goto pc+4")
-__xlated("5: if r11 == 0x0 goto pc+1")
+__xlated("2: r12 = r3")
+__xlated("3: r12 += 1")
+__xlated("4: if r12 > 0x1 goto pc+4")
+__xlated("5: if r12 == 0x0 goto pc+1")
__xlated("6: r2 = 0")
__xlated("7: r2 = -r2")
__xlated("8: goto pc+1")
@@ -890,10 +890,10 @@ __arch_x86_64
__xlated("0: w2 = -2147483648")
__xlated("1: w3 = -1")
__xlated("2: w4 = w2")
-__xlated("3: r11 = r3")
-__xlated("4: w11 += 1")
-__xlated("5: if w11 > 0x1 goto pc+4")
-__xlated("6: if w11 == 0x0 goto pc+1")
+__xlated("3: r12 = r3")
+__xlated("4: w12 += 1")
+__xlated("5: if w12 > 0x1 goto pc+4")
+__xlated("6: if w12 == 0x0 goto pc+1")
__xlated("7: w2 = 0")
__xlated("8: w2 = -w2")
__xlated("9: goto pc+1")
@@ -925,10 +925,10 @@ __arch_x86_64
__xlated("0: w2 = -5")
__xlated("1: w3 = -1")
__xlated("2: w4 = w2")
-__xlated("3: r11 = r3")
-__xlated("4: w11 += 1")
-__xlated("5: if w11 > 0x1 goto pc+4")
-__xlated("6: if w11 == 0x0 goto pc+1")
+__xlated("3: r12 = r3")
+__xlated("4: w12 += 1")
+__xlated("5: if w12 > 0x1 goto pc+4")
+__xlated("6: if w12 == 0x0 goto pc+1")
__xlated("7: w2 = 0")
__xlated("8: w2 = -w2")
__xlated("9: goto pc+1")
@@ -1004,10 +1004,10 @@ __arch_x86_64
__xlated("0: r2 = 0x8000000000000000")
__xlated("2: r3 = -1")
__xlated("3: r4 = r2")
-__xlated("4: r11 = r3")
-__xlated("5: r11 += 1")
-__xlated("6: if r11 > 0x1 goto pc+3")
-__xlated("7: if r11 == 0x1 goto pc+3")
+__xlated("4: r12 = r3")
+__xlated("5: r12 += 1")
+__xlated("6: if r12 > 0x1 goto pc+3")
+__xlated("7: if r12 == 0x1 goto pc+3")
__xlated("8: w2 = 0")
__xlated("9: goto pc+1")
__xlated("10: r2 s%= r3")
@@ -1034,10 +1034,10 @@ __arch_x86_64
__xlated("0: r2 = 5")
__xlated("1: r3 = -1")
__xlated("2: r4 = r2")
-__xlated("3: r11 = r3")
-__xlated("4: r11 += 1")
-__xlated("5: if r11 > 0x1 goto pc+3")
-__xlated("6: if r11 == 0x1 goto pc+3")
+__xlated("3: r12 = r3")
+__xlated("4: r12 += 1")
+__xlated("5: if r12 > 0x1 goto pc+3")
+__xlated("6: if r12 == 0x1 goto pc+3")
__xlated("7: w2 = 0")
__xlated("8: goto pc+1")
__xlated("9: r2 s%= r3")
@@ -1108,10 +1108,10 @@ __arch_x86_64
__xlated("0: w2 = -2147483648")
__xlated("1: w3 = -1")
__xlated("2: w4 = w2")
-__xlated("3: r11 = r3")
-__xlated("4: w11 += 1")
-__xlated("5: if w11 > 0x1 goto pc+3")
-__xlated("6: if w11 == 0x1 goto pc+4")
+__xlated("3: r12 = r3")
+__xlated("4: w12 += 1")
+__xlated("5: if w12 > 0x1 goto pc+3")
+__xlated("6: if w12 == 0x1 goto pc+4")
__xlated("7: w2 = 0")
__xlated("8: goto pc+1")
__xlated("9: w2 s%= w3")
@@ -1140,10 +1140,10 @@ __arch_x86_64
__xlated("0: w2 = -5")
__xlated("1: w3 = -1")
__xlated("2: w4 = w2")
-__xlated("3: r11 = r3")
-__xlated("4: w11 += 1")
-__xlated("5: if w11 > 0x1 goto pc+3")
-__xlated("6: if w11 == 0x1 goto pc+4")
+__xlated("3: r12 = r3")
+__xlated("4: w12 += 1")
+__xlated("5: if w12 > 0x1 goto pc+3")
+__xlated("6: if w12 == 0x1 goto pc+4")
__xlated("7: w2 = 0")
__xlated("8: goto pc+1")
__xlated("9: w2 s%= w3")
--
2.52.0
next prev parent reply other threads:[~2026-04-19 16:33 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-19 16:33 [PATCH bpf-next v6 00/17] bpf: Support stack arguments for BPF functions and kfuncs Yonghong Song
2026-04-19 16:33 ` [PATCH bpf-next v6 01/17] bpf: Remove unused parameter from check_map_kptr_access() Yonghong Song
2026-04-19 16:33 ` [PATCH bpf-next v6 02/17] bpf: Refactor to avoid redundant calculation of bpf_reg_state Yonghong Song
2026-04-19 16:33 ` [PATCH bpf-next v6 03/17] bpf: Refactor to handle memory and size together Yonghong Song
2026-04-20 23:58 ` Alexei Starovoitov
2026-04-21 4:04 ` Yonghong Song
2026-04-19 16:33 ` [PATCH bpf-next v6 04/17] bpf: Prepare verifier logs for upcoming kfunc stack arguments Yonghong Song
2026-04-21 0:03 ` Alexei Starovoitov
2026-04-21 4:06 ` Yonghong Song
2026-04-21 6:07 ` Yonghong Song
2026-04-21 13:48 ` Alexei Starovoitov
2026-04-21 15:41 ` Yonghong Song
2026-04-21 15:46 ` Alexei Starovoitov
2026-04-21 16:37 ` Yonghong Song
2026-04-21 17:24 ` Yonghong Song
2026-04-19 16:33 ` Yonghong Song [this message]
2026-04-19 17:06 ` [PATCH bpf-next v6 05/17] bpf: Introduce bpf register BPF_REG_PARAMS sashiko-bot
2026-04-19 18:14 ` Yonghong Song
2026-04-19 16:33 ` [PATCH bpf-next v6 06/17] bpf: Reuse MAX_BPF_FUNC_ARGS for maximum number of arguments Yonghong Song
2026-04-19 16:33 ` [PATCH bpf-next v6 07/17] bpf: Support stack arguments for bpf functions Yonghong Song
2026-04-19 19:15 ` sashiko-bot
2026-04-20 4:35 ` Yonghong Song
2026-04-21 0:37 ` Alexei Starovoitov
2026-04-21 4:15 ` Yonghong Song
2026-04-19 16:33 ` [PATCH bpf-next v6 08/17] bpf: Reject stack arguments in non-JITed programs Yonghong Song
2026-04-19 18:21 ` sashiko-bot
2026-04-20 4:23 ` Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 09/17] bpf: Track r11 registers in const_fold and liveness Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 10/17] bpf: Prepare architecture JIT support for stack arguments Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 11/17] bpf: Enable r11 based insns Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 12/17] bpf: Support stack arguments for kfunc calls Yonghong Song
2026-04-19 17:08 ` sashiko-bot
2026-04-19 18:18 ` Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 13/17] bpf: Reject stack arguments if tail call reachable Yonghong Song
2026-04-19 17:08 ` sashiko-bot
2026-04-19 18:20 ` Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 14/17] bpf,x86: Implement JIT support for stack arguments Yonghong Song
2026-04-19 17:25 ` sashiko-bot
2026-04-19 18:55 ` Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 15/17] selftests/bpf: Add tests for BPF function " Yonghong Song
2026-04-19 17:15 ` sashiko-bot
2026-04-20 5:52 ` Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 16/17] selftests/bpf: Add tests for stack argument validation Yonghong Song
2026-04-19 16:34 ` [PATCH bpf-next v6 17/17] selftests/bpf: Add verifier " Yonghong Song
2026-04-19 17:21 ` sashiko-bot
2026-04-20 6:14 ` Yonghong Song
2026-04-20 15:41 ` [PATCH bpf-next v6 00/17] bpf: Support stack arguments for BPF functions and kfuncs Puranjay Mohan
2026-04-20 20:22 ` Yonghong Song
2026-04-20 20:25 ` Puranjay Mohan
2026-04-20 21:49 ` Alexei Starovoitov
2026-04-20 23:44 ` Yonghong Song
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