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 v5 05/16] bpf: Introduce bpf register BPF_REG_PARAMS
Date: Thu, 16 Apr 2026 20:47:24 -0700 [thread overview]
Message-ID: <20260417034724.2628054-1-yonghong.song@linux.dev> (raw)
In-Reply-To: <20260417034658.2625353-1-yonghong.song@linux.dev>
The newly-added register BPF_REG_PARAMS corresponds to bpf
register R11 in llvm. R11 is used as the base for stack arguments
so it won't mess out R10 based stacks. The kernel internal
register BPF_REG_AX was R11 previously. With this change,
BPF_REG_AX will be R12.
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 f552170eacf4..ae094328d973 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 066b86e7233c..e7e97ffa2a8b 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:[~2026-04-17 3:47 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-17 3:46 [PATCH bpf-next v5 00/16] bpf: Support stack arguments for BPF functions and kfuncs Yonghong Song
2026-04-17 3:47 ` [PATCH bpf-next v5 01/16] bpf: Remove unused parameter from check_map_kptr_access() Yonghong Song
2026-04-17 3:47 ` [PATCH bpf-next v5 02/16] bpf: Refactor to avoid redundant calculation of bpf_reg_state Yonghong Song
2026-04-17 3:47 ` [PATCH bpf-next v5 03/16] bpf: Refactor to handle memory and size together Yonghong Song
2026-04-17 4:49 ` sashiko-bot
2026-04-18 16:40 ` Yonghong Song
2026-04-18 0:52 ` bot+bpf-ci
2026-04-18 16:47 ` Yonghong Song
2026-04-17 3:47 ` [PATCH bpf-next v5 04/16] bpf: Prepare verifier logs for upcoming kfunc stack arguments Yonghong Song
2026-04-17 3:47 ` Yonghong Song [this message]
2026-04-17 3:47 ` [PATCH bpf-next v5 06/16] bpf: Limit the scope of BPF_REG_PARAMS usage Yonghong Song
2026-04-17 4:30 ` bot+bpf-ci
2026-04-18 16:48 ` Yonghong Song
2026-04-17 4:50 ` sashiko-bot
2026-04-18 16:50 ` Yonghong Song
2026-04-18 1:04 ` bot+bpf-ci
2026-04-18 16:54 ` Yonghong Song
2026-04-17 3:47 ` [PATCH bpf-next v5 07/16] bpf: Reuse MAX_BPF_FUNC_ARGS for maximum number of arguments Yonghong Song
2026-04-17 4:30 ` bot+bpf-ci
2026-04-18 17:00 ` Yonghong Song
2026-04-18 0:52 ` bot+bpf-ci
2026-04-18 17:03 ` Yonghong Song
2026-04-17 3:47 ` [PATCH bpf-next v5 08/16] bpf: Support stack arguments for bpf functions Yonghong Song
2026-04-17 4:35 ` sashiko-bot
2026-04-18 17:10 ` Yonghong Song
2026-04-17 4:43 ` bot+bpf-ci
2026-04-18 17:11 ` Yonghong Song
2026-04-18 1:04 ` bot+bpf-ci
2026-04-17 3:47 ` [PATCH bpf-next v5 09/16] bpf: Reject stack arguments in non-JITed programs Yonghong Song
2026-04-17 4:30 ` bot+bpf-ci
2026-04-18 17:17 ` Yonghong Song
2026-04-18 0:52 ` bot+bpf-ci
2026-04-17 3:47 ` [PATCH bpf-next v5 10/16] bpf: Reject stack arguments if tail call reachable Yonghong Song
2026-04-17 4:08 ` sashiko-bot
2026-04-18 17:18 ` Yonghong Song
2026-04-18 17:37 ` Yonghong Song
2026-04-17 4:30 ` bot+bpf-ci
2026-04-18 1:04 ` bot+bpf-ci
2026-04-18 17:24 ` Yonghong Song
2026-04-17 3:47 ` [PATCH bpf-next v5 11/16] bpf: Support stack arguments for kfunc calls Yonghong Song
2026-04-17 4:40 ` sashiko-bot
2026-04-18 17:46 ` Yonghong Song
2026-04-17 4:43 ` bot+bpf-ci
2026-04-18 17:57 ` Yonghong Song
2026-04-18 1:04 ` bot+bpf-ci
2026-04-18 18:04 ` Yonghong Song
2026-04-17 3:47 ` [PATCH bpf-next v5 12/16] bpf: Enable stack argument support for x86_64 Yonghong Song
2026-04-17 4:30 ` bot+bpf-ci
2026-04-17 5:03 ` sashiko-bot
2026-04-18 18:07 ` Yonghong Song
2026-04-18 1:04 ` bot+bpf-ci
2026-04-17 3:48 ` [PATCH bpf-next v5 13/16] bpf,x86: Implement JIT support for stack arguments Yonghong Song
2026-04-17 4:44 ` sashiko-bot
2026-04-18 16:43 ` Puranjay Mohan
2026-04-18 18:15 ` Yonghong Song
2026-04-18 1:20 ` bot+bpf-ci
2026-04-18 18:23 ` Yonghong Song
2026-04-17 3:48 ` [PATCH bpf-next v5 14/16] selftests/bpf: Add tests for BPF function " Yonghong Song
2026-04-17 4:20 ` sashiko-bot
2026-04-18 0:52 ` bot+bpf-ci
2026-04-18 18:26 ` Yonghong Song
2026-04-17 3:48 ` [PATCH bpf-next v5 15/16] selftests/bpf: Add negative test for greater-than-8-byte kfunc stack argument Yonghong Song
2026-04-17 4:28 ` sashiko-bot
2026-04-18 18:29 ` Yonghong Song
2026-04-18 0:52 ` bot+bpf-ci
2026-04-17 3:48 ` [PATCH bpf-next v5 16/16] selftests/bpf: Add verifier tests for stack argument validation Yonghong Song
2026-04-17 4:38 ` sashiko-bot
2026-04-18 18:36 ` Yonghong Song
2026-04-18 0:52 ` bot+bpf-ci
2026-04-18 16:39 ` [PATCH bpf-next v5 00/16] bpf: Support stack arguments for BPF functions and kfuncs Puranjay Mohan
2026-04-18 18:47 ` Alexei Starovoitov
2026-04-18 18:54 ` Yonghong Song
2026-04-18 17:06 ` Puranjay Mohan
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