--- /dev/null
+From 42326ded4ed3ba52ee6a6e244efe97f0fa4f4281 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Mon, 15 Jun 2026 00:58:39 +0800
+Subject: bpf: Remove mark_precise_scalar_ids()
+
+From: Eduard Zingerman <eddyz87@gmail.com>
+
+[ Upstream commit 842edb5507a1038e009d27e69d13b94b6f085763 ]
+
+Function mark_precise_scalar_ids() is superseded by
+bt_sync_linked_regs() and equal scalars tracking in jump history.
+mark_precise_scalar_ids() propagates precision over registers sharing
+same ID on parent/child state boundaries, while jump history records
+allow bt_sync_linked_regs() to propagate same information with
+instruction level granularity, which is strictly more precise.
+
+This commit removes mark_precise_scalar_ids() and updates test cases
+in progs/verifier_scalar_ids to reflect new verifier behavior.
+
+The tests are updated in the following manner:
+- mark_precise_scalar_ids() propagated precision regardless of
+ presence of conditional jumps, while new jump history based logic
+ only kicks in when conditional jumps are present.
+ Hence test cases are augmented with conditional jumps to still
+ trigger precision propagation.
+- As equal scalars tracking no longer relies on parent/child state
+ boundaries some test cases are no longer interesting,
+ such test cases are removed, namely:
+ - precision_same_state and precision_cross_state are superseded by
+ linked_regs_bpf_k;
+ - precision_same_state_broken_link and equal_scalars_broken_link
+ are superseded by linked_regs_broken_link.
+
+Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
+Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
+Link: https://lore.kernel.org/bpf/20240718202357.1746514-3-eddyz87@gmail.com
+[ zhenzhong: backport to 6.6.y after adapting the first linked-regs
+ history commit to the older scalar-id verifier layout. ]
+Signed-off-by: Zhenzhong Wu <jt26wzz@gmail.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ kernel/bpf/verifier.c | 115 ------------
+ .../selftests/bpf/progs/verifier_scalar_ids.c | 171 ++++++------------
+ .../testing/selftests/bpf/verifier/precise.c | 2 +-
+ 3 files changed, 56 insertions(+), 232 deletions(-)
+
+diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
+index 3cc0fc90244f7b..55a5a5bed1ab68 100644
+--- a/kernel/bpf/verifier.c
++++ b/kernel/bpf/verifier.c
+@@ -4265,96 +4265,6 @@ static void mark_all_scalars_imprecise(struct bpf_verifier_env *env, struct bpf_
+ }
+ }
+
+-static bool idset_contains(struct bpf_idset *s, u32 id)
+-{
+- u32 i;
+-
+- for (i = 0; i < s->count; ++i)
+- if (s->ids[i] == id)
+- return true;
+-
+- return false;
+-}
+-
+-static int idset_push(struct bpf_idset *s, u32 id)
+-{
+- if (WARN_ON_ONCE(s->count >= ARRAY_SIZE(s->ids)))
+- return -EFAULT;
+- s->ids[s->count++] = id;
+- return 0;
+-}
+-
+-static void idset_reset(struct bpf_idset *s)
+-{
+- s->count = 0;
+-}
+-
+-/* Collect a set of IDs for all registers currently marked as precise in env->bt.
+- * Mark all registers with these IDs as precise.
+- */
+-static int mark_precise_scalar_ids(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
+-{
+- struct bpf_idset *precise_ids = &env->idset_scratch;
+- struct backtrack_state *bt = &env->bt;
+- struct bpf_func_state *func;
+- struct bpf_reg_state *reg;
+- DECLARE_BITMAP(mask, 64);
+- int i, fr;
+-
+- idset_reset(precise_ids);
+-
+- for (fr = bt->frame; fr >= 0; fr--) {
+- func = st->frame[fr];
+-
+- bitmap_from_u64(mask, bt_frame_reg_mask(bt, fr));
+- for_each_set_bit(i, mask, 32) {
+- reg = &func->regs[i];
+- if (!reg->id || reg->type != SCALAR_VALUE)
+- continue;
+- if (idset_push(precise_ids, reg->id))
+- return -EFAULT;
+- }
+-
+- bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr));
+- for_each_set_bit(i, mask, 64) {
+- if (i >= func->allocated_stack / BPF_REG_SIZE)
+- break;
+- if (!is_spilled_scalar_reg(&func->stack[i]))
+- continue;
+- reg = &func->stack[i].spilled_ptr;
+- if (!reg->id)
+- continue;
+- if (idset_push(precise_ids, reg->id))
+- return -EFAULT;
+- }
+- }
+-
+- for (fr = 0; fr <= st->curframe; ++fr) {
+- func = st->frame[fr];
+-
+- for (i = BPF_REG_0; i < BPF_REG_10; ++i) {
+- reg = &func->regs[i];
+- if (!reg->id)
+- continue;
+- if (!idset_contains(precise_ids, reg->id))
+- continue;
+- bt_set_frame_reg(bt, fr, i);
+- }
+- for (i = 0; i < func->allocated_stack / BPF_REG_SIZE; ++i) {
+- if (!is_spilled_scalar_reg(&func->stack[i]))
+- continue;
+- reg = &func->stack[i].spilled_ptr;
+- if (!reg->id)
+- continue;
+- if (!idset_contains(precise_ids, reg->id))
+- continue;
+- bt_set_frame_slot(bt, fr, i);
+- }
+- }
+-
+- return 0;
+-}
+-
+ /*
+ * __mark_chain_precision() backtracks BPF program instruction sequence and
+ * chain of verifier states making sure that register *regno* (if regno >= 0)
+@@ -4487,31 +4397,6 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)
+ bt->frame, last_idx, first_idx, subseq_idx);
+ }
+
+- /* If some register with scalar ID is marked as precise,
+- * make sure that all registers sharing this ID are also precise.
+- * This is needed to estimate effect of sync_linked_regs().
+- * Do this at the last instruction of each state,
+- * bpf_reg_state::id fields are valid for these instructions.
+- *
+- * Allows to track precision in situation like below:
+- *
+- * r2 = unknown value
+- * ...
+- * --- state #0 ---
+- * ...
+- * r1 = r2 // r1 and r2 now share the same ID
+- * ...
+- * --- state #1 {r1.id = A, r2.id = A} ---
+- * ...
+- * if (r2 > 10) goto exit; // sync_linked_regs() assigns range to r1
+- * ...
+- * --- state #2 {r1.id = A, r2.id = A} ---
+- * r3 = r10
+- * r3 += r1 // need to mark both r1 and r2
+- */
+- if (mark_precise_scalar_ids(env, st))
+- return -EFAULT;
+-
+ if (last_idx < 0) {
+ /* we are at the entry into subprog, which
+ * is expected for global funcs, but only if
+diff --git a/tools/testing/selftests/bpf/progs/verifier_scalar_ids.c b/tools/testing/selftests/bpf/progs/verifier_scalar_ids.c
+index 22a6cf6e8255df..f70392bf696c62 100644
+--- a/tools/testing/selftests/bpf/progs/verifier_scalar_ids.c
++++ b/tools/testing/selftests/bpf/progs/verifier_scalar_ids.c
+@@ -5,54 +5,27 @@
+ #include "bpf_misc.h"
+
+ /* Check that precision marks propagate through scalar IDs.
+- * Registers r{0,1,2} have the same scalar ID at the moment when r0 is
+- * marked to be precise, this mark is immediately propagated to r{1,2}.
++ * Registers r{0,1,2} have the same scalar ID.
++ * Range information is propagated for scalars sharing same ID.
++ * Check that precision mark for r0 causes precision marks for r{1,2}
++ * when range information is propagated for 'if <reg> <op> <const>' insn.
+ */
+ SEC("socket")
+ __success __log_level(2)
+-__msg("frame0: regs=r0,r1,r2 stack= before 4: (bf) r3 = r10")
+-__msg("frame0: regs=r0,r1,r2 stack= before 3: (bf) r2 = r0")
+-__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")
+-__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")
+-__msg("frame0: regs=r0 stack= before 0: (85) call bpf_ktime_get_ns")
+-__flag(BPF_F_TEST_STATE_FREQ)
+-__naked void precision_same_state(void)
+-{
+- asm volatile (
+- /* r0 = random number up to 0xff */
+- "call %[bpf_ktime_get_ns];"
+- "r0 &= 0xff;"
+- /* tie r0.id == r1.id == r2.id */
+- "r1 = r0;"
+- "r2 = r0;"
+- /* force r0 to be precise, this immediately marks r1 and r2 as
+- * precise as well because of shared IDs
+- */
+- "r3 = r10;"
+- "r3 += r0;"
+- "r0 = 0;"
+- "exit;"
+- :
+- : __imm(bpf_ktime_get_ns)
+- : __clobber_all);
+-}
+-
+-/* Same as precision_same_state, but mark propagates through state /
+- * parent state boundary.
+- */
+-SEC("socket")
+-__success __log_level(2)
+-__msg("frame0: last_idx 6 first_idx 5 subseq_idx -1")
+-__msg("frame0: regs=r0,r1,r2 stack= before 5: (bf) r3 = r10")
++/* first 'if' branch */
++__msg("6: (0f) r3 += r0")
++__msg("frame0: regs=r0 stack= before 4: (25) if r1 > 0x7 goto pc+0")
+ __msg("frame0: parent state regs=r0,r1,r2 stack=:")
+-__msg("frame0: regs=r0,r1,r2 stack= before 4: (05) goto pc+0")
+ __msg("frame0: regs=r0,r1,r2 stack= before 3: (bf) r2 = r0")
+-__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")
+-__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")
+-__msg("frame0: parent state regs=r0 stack=:")
+-__msg("frame0: regs=r0 stack= before 0: (85) call bpf_ktime_get_ns")
++/* second 'if' branch */
++__msg("from 4 to 5: ")
++__msg("6: (0f) r3 += r0")
++__msg("frame0: regs=r0 stack= before 5: (bf) r3 = r10")
++__msg("frame0: regs=r0 stack= before 4: (25) if r1 > 0x7 goto pc+0")
++/* parent state already has r{0,1,2} as precise */
++__msg("frame0: parent state regs= stack=:")
+ __flag(BPF_F_TEST_STATE_FREQ)
+-__naked void precision_cross_state(void)
++__naked void linked_regs_bpf_k(void)
+ {
+ asm volatile (
+ /* r0 = random number up to 0xff */
+@@ -61,9 +34,8 @@ __naked void precision_cross_state(void)
+ /* tie r0.id == r1.id == r2.id */
+ "r1 = r0;"
+ "r2 = r0;"
+- /* force checkpoint */
+- "goto +0;"
+- /* force r0 to be precise, this immediately marks r1 and r2 as
++ "if r1 > 7 goto +0;"
++ /* force r0 to be precise, this eventually marks r1 and r2 as
+ * precise as well because of shared IDs
+ */
+ "r3 = r10;"
+@@ -75,59 +47,18 @@ __naked void precision_cross_state(void)
+ : __clobber_all);
+ }
+
+-/* Same as precision_same_state, but break one of the
++/* Same as linked_regs_bpf_k, but break one of the
+ * links, note that r1 is absent from regs=... in __msg below.
+ */
+ SEC("socket")
+ __success __log_level(2)
+-__msg("frame0: regs=r0,r2 stack= before 5: (bf) r3 = r10")
+-__msg("frame0: regs=r0,r2 stack= before 4: (b7) r1 = 0")
+-__msg("frame0: regs=r0,r2 stack= before 3: (bf) r2 = r0")
+-__msg("frame0: regs=r0 stack= before 2: (bf) r1 = r0")
+-__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")
+-__msg("frame0: regs=r0 stack= before 0: (85) call bpf_ktime_get_ns")
+-__flag(BPF_F_TEST_STATE_FREQ)
+-__naked void precision_same_state_broken_link(void)
+-{
+- asm volatile (
+- /* r0 = random number up to 0xff */
+- "call %[bpf_ktime_get_ns];"
+- "r0 &= 0xff;"
+- /* tie r0.id == r1.id == r2.id */
+- "r1 = r0;"
+- "r2 = r0;"
+- /* break link for r1, this is the only line that differs
+- * compared to the previous test
+- */
+- "r1 = 0;"
+- /* force r0 to be precise, this immediately marks r1 and r2 as
+- * precise as well because of shared IDs
+- */
+- "r3 = r10;"
+- "r3 += r0;"
+- "r0 = 0;"
+- "exit;"
+- :
+- : __imm(bpf_ktime_get_ns)
+- : __clobber_all);
+-}
+-
+-/* Same as precision_same_state_broken_link, but with state /
+- * parent state boundary.
+- */
+-SEC("socket")
+-__success __log_level(2)
+-__msg("frame0: regs=r0,r2 stack= before 6: (bf) r3 = r10")
+-__msg("frame0: regs=r0,r2 stack= before 5: (b7) r1 = 0")
+-__msg("frame0: parent state regs=r0,r2 stack=:")
+-__msg("frame0: regs=r0,r1,r2 stack= before 4: (05) goto pc+0")
+-__msg("frame0: regs=r0,r1,r2 stack= before 3: (bf) r2 = r0")
+-__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")
+-__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")
++__msg("7: (0f) r3 += r0")
++__msg("frame0: regs=r0 stack= before 6: (bf) r3 = r10")
+ __msg("frame0: parent state regs=r0 stack=:")
+-__msg("frame0: regs=r0 stack= before 0: (85) call bpf_ktime_get_ns")
++__msg("frame0: regs=r0 stack= before 5: (25) if r0 > 0x7 goto pc+0")
++__msg("frame0: parent state regs=r0,r2 stack=:")
+ __flag(BPF_F_TEST_STATE_FREQ)
+-__naked void precision_cross_state_broken_link(void)
++__naked void linked_regs_broken_link(void)
+ {
+ asm volatile (
+ /* r0 = random number up to 0xff */
+@@ -136,18 +67,13 @@ __naked void precision_cross_state_broken_link(void)
+ /* tie r0.id == r1.id == r2.id */
+ "r1 = r0;"
+ "r2 = r0;"
+- /* force checkpoint, although link between r1 and r{0,2} is
+- * broken by the next statement current precision tracking
+- * algorithm can't react to it and propagates mark for r1 to
+- * the parent state.
+- */
+- "goto +0;"
+ /* break link for r1, this is the only line that differs
+- * compared to precision_cross_state()
++ * compared to the previous test
+ */
+ "r1 = 0;"
+- /* force r0 to be precise, this immediately marks r1 and r2 as
+- * precise as well because of shared IDs
++ "if r0 > 7 goto +0;"
++ /* force r0 to be precise,
++ * this eventually marks r2 as precise because of shared IDs
+ */
+ "r3 = r10;"
+ "r3 += r0;"
+@@ -164,10 +90,16 @@ __naked void precision_cross_state_broken_link(void)
+ */
+ SEC("socket")
+ __success __log_level(2)
+-__msg("11: (0f) r2 += r1")
++__msg("12: (0f) r2 += r1")
+ /* Current state */
+-__msg("frame2: last_idx 11 first_idx 10 subseq_idx -1")
+-__msg("frame2: regs=r1 stack= before 10: (bf) r2 = r10")
++__msg("frame2: last_idx 12 first_idx 11 subseq_idx -1 ")
++__msg("frame2: regs=r1 stack= before 11: (bf) r2 = r10")
++__msg("frame2: parent state regs=r1 stack=")
++__msg("frame1: parent state regs= stack=")
++__msg("frame0: parent state regs= stack=")
++/* Parent state */
++__msg("frame2: last_idx 10 first_idx 10 subseq_idx 11 ")
++__msg("frame2: regs=r1 stack= before 10: (25) if r1 > 0x7 goto pc+0")
+ __msg("frame2: parent state regs=r1 stack=")
+ /* frame1.r{6,7} are marked because mark_precise_scalar_ids()
+ * looks for all registers with frame2.r1.id in the current state
+@@ -192,7 +124,7 @@ __msg("frame1: regs=r1 stack= before 4: (85) call pc+1")
+ __msg("frame0: parent state regs=r1,r6 stack=")
+ /* Parent state */
+ __msg("frame0: last_idx 3 first_idx 1 subseq_idx 4")
+-__msg("frame0: regs=r0,r1,r6 stack= before 3: (bf) r6 = r0")
++__msg("frame0: regs=r1,r6 stack= before 3: (bf) r6 = r0")
+ __msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")
+ __msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")
+ __flag(BPF_F_TEST_STATE_FREQ)
+@@ -230,7 +162,8 @@ static __naked __noinline __used
+ void precision_many_frames__bar(void)
+ {
+ asm volatile (
+- /* force r1 to be precise, this immediately marks:
++ "if r1 > 7 goto +0;"
++ /* force r1 to be precise, this eventually marks:
+ * - bar frame r1
+ * - foo frame r{1,6,7}
+ * - main frame r{1,6}
+@@ -247,14 +180,16 @@ void precision_many_frames__bar(void)
+ */
+ SEC("socket")
+ __success __log_level(2)
++__msg("11: (0f) r2 += r1")
+ /* foo frame */
+-__msg("frame1: regs=r1 stack=-8,-16 before 9: (bf) r2 = r10")
++__msg("frame1: regs=r1 stack= before 10: (bf) r2 = r10")
++__msg("frame1: regs=r1 stack= before 9: (25) if r1 > 0x7 goto pc+0")
+ __msg("frame1: regs=r1 stack=-8,-16 before 8: (7b) *(u64 *)(r10 -16) = r1")
+ __msg("frame1: regs=r1 stack=-8 before 7: (7b) *(u64 *)(r10 -8) = r1")
+ __msg("frame1: regs=r1 stack= before 4: (85) call pc+2")
+ /* main frame */
+-__msg("frame0: regs=r0,r1 stack=-8 before 3: (7b) *(u64 *)(r10 -8) = r1")
+-__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")
++__msg("frame0: regs=r1 stack=-8 before 3: (7b) *(u64 *)(r10 -8) = r1")
++__msg("frame0: regs=r1 stack= before 2: (bf) r1 = r0")
+ __msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")
+ __flag(BPF_F_TEST_STATE_FREQ)
+ __naked void precision_stack(void)
+@@ -283,7 +218,8 @@ void precision_stack__foo(void)
+ */
+ "*(u64*)(r10 - 8) = r1;"
+ "*(u64*)(r10 - 16) = r1;"
+- /* force r1 to be precise, this immediately marks:
++ "if r1 > 7 goto +0;"
++ /* force r1 to be precise, this eventually marks:
+ * - foo frame r1,fp{-8,-16}
+ * - main frame r1,fp{-8}
+ */
+@@ -299,15 +235,17 @@ void precision_stack__foo(void)
+ SEC("socket")
+ __success __log_level(2)
+ /* r{6,7} */
+-__msg("11: (0f) r3 += r7")
+-__msg("frame0: regs=r6,r7 stack= before 10: (bf) r3 = r10")
++__msg("12: (0f) r3 += r7")
++__msg("frame0: regs=r7 stack= before 11: (bf) r3 = r10")
++__msg("frame0: regs=r7 stack= before 9: (25) if r7 > 0x7 goto pc+0")
+ /* ... skip some insns ... */
+ __msg("frame0: regs=r6,r7 stack= before 3: (bf) r7 = r0")
+ __msg("frame0: regs=r0,r6 stack= before 2: (bf) r6 = r0")
+ /* r{8,9} */
+-__msg("12: (0f) r3 += r9")
+-__msg("frame0: regs=r8,r9 stack= before 11: (0f) r3 += r7")
++__msg("13: (0f) r3 += r9")
++__msg("frame0: regs=r9 stack= before 12: (0f) r3 += r7")
+ /* ... skip some insns ... */
++__msg("frame0: regs=r9 stack= before 10: (25) if r9 > 0x7 goto pc+0")
+ __msg("frame0: regs=r8,r9 stack= before 7: (bf) r9 = r0")
+ __msg("frame0: regs=r0,r8 stack= before 6: (bf) r8 = r0")
+ __flag(BPF_F_TEST_STATE_FREQ)
+@@ -328,8 +266,9 @@ __naked void precision_two_ids(void)
+ "r9 = r0;"
+ /* clear r0 id */
+ "r0 = 0;"
+- /* force checkpoint */
+- "goto +0;"
++ /* propagate equal scalars precision */
++ "if r7 > 7 goto +0;"
++ "if r9 > 7 goto +0;"
+ "r3 = r10;"
+ /* force r7 to be precise, this also marks r6 */
+ "r3 += r7;"
+diff --git a/tools/testing/selftests/bpf/verifier/precise.c b/tools/testing/selftests/bpf/verifier/precise.c
+index 8a2ff81d835088..17fbc1e6150e3f 100644
+--- a/tools/testing/selftests/bpf/verifier/precise.c
++++ b/tools/testing/selftests/bpf/verifier/precise.c
+@@ -106,7 +106,7 @@
+ mark_precise: frame0: regs=r2 stack= before 22\
+ mark_precise: frame0: parent state regs=r2 stack=:\
+ mark_precise: frame0: last_idx 20 first_idx 20\
+- mark_precise: frame0: regs=r2,r9 stack= before 20\
++ mark_precise: frame0: regs=r2 stack= before 20\
+ mark_precise: frame0: parent state regs=r2,r9 stack=:\
+ mark_precise: frame0: last_idx 19 first_idx 17\
+ mark_precise: frame0: regs=r2,r9 stack= before 19\
+--
+2.53.0
+
--- /dev/null
+From 9c678aa8b0ac9b3753b17834fed7961f42df9627 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Mon, 15 Jun 2026 00:58:38 +0800
+Subject: bpf: Track equal scalars history on per-instruction level
+
+From: Eduard Zingerman <eddyz87@gmail.com>
+
+[ Upstream commit 4bf79f9be434e000c8e12fe83b2f4402480f1460 ]
+
+Use bpf_verifier_state->jmp_history to track which registers were
+updated by find_equal_scalars() (renamed to collect_linked_regs())
+when conditional jump was verified. Use recorded information in
+backtrack_insn() to propagate precision.
+
+E.g. for the following program:
+
+ while verifying instructions
+ 1: r1 = r0 |
+ 2: if r1 < 8 goto ... | push r0,r1 as linked registers in jmp_history
+ 3: if r0 > 16 goto ... | push r0,r1 as linked registers in jmp_history
+ 4: r2 = r10 |
+ 5: r2 += r0 v mark_chain_precision(r0)
+
+ while doing mark_chain_precision(r0)
+ 5: r2 += r0 | mark r0 precise
+ 4: r2 = r10 |
+ 3: if r0 > 16 goto ... | mark r0,r1 as precise
+ 2: if r1 < 8 goto ... | mark r0,r1 as precise
+ 1: r1 = r0 v
+
+Technically, do this as follows:
+- Use 10 bits to identify each register that gains range because of
+ sync_linked_regs():
+ - 3 bits for frame number;
+ - 6 bits for register or stack slot number;
+ - 1 bit to indicate if register is spilled.
+- Use u64 as a vector of 6 such records + 4 bits for vector length.
+- Augment struct bpf_jmp_history_entry with a field 'linked_regs'
+ representing such vector.
+- When doing check_cond_jmp_op() remember up to 6 registers that
+ gain range because of sync_linked_regs() in such a vector.
+- Don't propagate range information and reset IDs for registers that
+ don't fit in 6-value vector.
+- Push a pair {instruction index, linked registers vector}
+ to bpf_verifier_state->jmp_history.
+- When doing backtrack_insn() check if any of recorded linked
+ registers is currently marked precise, if so mark all linked
+ registers as precise.
+
+This also requires fixes for two test_verifier tests:
+- precise: test 1
+- precise: test 2
+
+Both tests contain the following instruction sequence:
+
+19: (bf) r2 = r9 ; R2=scalar(id=3) R9=scalar(id=3)
+20: (a5) if r2 < 0x8 goto pc+1 ; R2=scalar(id=3,umin=8)
+21: (95) exit
+22: (07) r2 += 1 ; R2_w=scalar(id=3+1,...)
+23: (bf) r1 = r10 ; R1_w=fp0 R10=fp0
+24: (07) r1 += -8 ; R1_w=fp-8
+25: (b7) r3 = 0 ; R3_w=0
+26: (85) call bpf_probe_read_kernel#113
+
+The call to bpf_probe_read_kernel() at (26) forces r2 to be precise.
+Previously, this forced all registers with same id to become precise
+immediately when mark_chain_precision() is called.
+After this change, the precision is propagated to registers sharing
+same id only when 'if' instruction is backtracked.
+Hence verification log for both tests is changed:
+regs=r2,r9 -> regs=r2 for instructions 25..20.
+
+Fixes: 904e6ddf4133 ("bpf: Use scalar ids in mark_chain_precision()")
+Reported-by: Hao Sun <sunhao.th@gmail.com>
+Suggested-by: Andrii Nakryiko <andrii@kernel.org>
+Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
+Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
+Link: https://lore.kernel.org/bpf/20240718202357.1746514-2-eddyz87@gmail.com
+Closes: https://lore.kernel.org/bpf/CAEf4BzZ0xidVCqB47XnkXcNhkPWF6_nTV7yt+_Lf0kcFEut2Mg@mail.gmail.com/
+[ zhenzhong: backport to 6.6.y verifier layout and adapt
+ sync_linked_regs() to the pre-BPF_ADD_CONST scalar-id code. ]
+Signed-off-by: Zhenzhong Wu <jt26wzz@gmail.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ include/linux/bpf_verifier.h | 4 +
+ kernel/bpf/verifier.c | 256 ++++++++++++++++--
+ .../bpf/progs/verifier_subprog_precision.c | 2 +-
+ 3 files changed, 239 insertions(+), 23 deletions(-)
+
+diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
+index dba211d3bb9a0d..9a3b93c24f19f5 100644
+--- a/include/linux/bpf_verifier.h
++++ b/include/linux/bpf_verifier.h
+@@ -345,6 +345,10 @@ struct bpf_jmp_history_entry {
+ u32 prev_idx : 22;
+ /* special flags, e.g., whether insn is doing register stack spill/load */
+ u32 flags : 10;
++ /* additional registers that need precision tracking when this
++ * jump is backtracked, vector of six 10-bit records
++ */
++ u64 linked_regs;
+ };
+
+ /* Maximum number of register states that can exist at once */
+diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
+index 0d90236d0ad94f..3cc0fc90244f7b 100644
+--- a/kernel/bpf/verifier.c
++++ b/kernel/bpf/verifier.c
+@@ -3461,9 +3461,87 @@ static bool is_jmp_point(struct bpf_verifier_env *env, int insn_idx)
+ return env->insn_aux_data[insn_idx].jmp_point;
+ }
+
++#define LR_FRAMENO_BITS 3
++#define LR_SPI_BITS 6
++#define LR_ENTRY_BITS (LR_SPI_BITS + LR_FRAMENO_BITS + 1)
++#define LR_SIZE_BITS 4
++#define LR_FRAMENO_MASK ((1ull << LR_FRAMENO_BITS) - 1)
++#define LR_SPI_MASK ((1ull << LR_SPI_BITS) - 1)
++#define LR_SIZE_MASK ((1ull << LR_SIZE_BITS) - 1)
++#define LR_SPI_OFF LR_FRAMENO_BITS
++#define LR_IS_REG_OFF (LR_SPI_BITS + LR_FRAMENO_BITS)
++#define LINKED_REGS_MAX 6
++
++struct linked_reg {
++ u8 frameno;
++ union {
++ u8 spi;
++ u8 regno;
++ };
++ bool is_reg;
++};
++
++struct linked_regs {
++ int cnt;
++ struct linked_reg entries[LINKED_REGS_MAX];
++};
++
++static struct linked_reg *linked_regs_push(struct linked_regs *s)
++{
++ if (s->cnt < LINKED_REGS_MAX)
++ return &s->entries[s->cnt++];
++
++ return NULL;
++}
++
++/* Use u64 as a vector of 6 10-bit values, use first 4-bits to track
++ * number of elements currently in stack.
++ * Pack one history entry for linked registers as 10 bits in the following format:
++ * - 3-bits frameno
++ * - 6-bits spi_or_reg
++ * - 1-bit is_reg
++ */
++static u64 linked_regs_pack(struct linked_regs *s)
++{
++ u64 val = 0;
++ int i;
++
++ for (i = 0; i < s->cnt; ++i) {
++ struct linked_reg *e = &s->entries[i];
++ u64 tmp = 0;
++
++ tmp |= e->frameno;
++ tmp |= e->spi << LR_SPI_OFF;
++ tmp |= (e->is_reg ? 1 : 0) << LR_IS_REG_OFF;
++
++ val <<= LR_ENTRY_BITS;
++ val |= tmp;
++ }
++ val <<= LR_SIZE_BITS;
++ val |= s->cnt;
++ return val;
++}
++
++static void linked_regs_unpack(u64 val, struct linked_regs *s)
++{
++ int i;
++
++ s->cnt = val & LR_SIZE_MASK;
++ val >>= LR_SIZE_BITS;
++
++ for (i = 0; i < s->cnt; ++i) {
++ struct linked_reg *e = &s->entries[i];
++
++ e->frameno = val & LR_FRAMENO_MASK;
++ e->spi = (val >> LR_SPI_OFF) & LR_SPI_MASK;
++ e->is_reg = (val >> LR_IS_REG_OFF) & 0x1;
++ val >>= LR_ENTRY_BITS;
++ }
++}
++
+ /* for any branch, call, exit record the history of jmps in the given state */
+ static int push_jmp_history(struct bpf_verifier_env *env, struct bpf_verifier_state *cur,
+- int insn_flags)
++ int insn_flags, u64 linked_regs)
+ {
+ u32 cnt = cur->jmp_history_cnt;
+ struct bpf_jmp_history_entry *p;
+@@ -3479,6 +3557,10 @@ static int push_jmp_history(struct bpf_verifier_env *env, struct bpf_verifier_st
+ "verifier insn history bug: insn_idx %d cur flags %x new flags %x\n",
+ env->insn_idx, env->cur_hist_ent->flags, insn_flags);
+ env->cur_hist_ent->flags |= insn_flags;
++ WARN_ONCE(env->cur_hist_ent->linked_regs != 0,
++ "verifier insn history bug: insn_idx %d linked_regs != 0: %#llx\n",
++ env->insn_idx, env->cur_hist_ent->linked_regs);
++ env->cur_hist_ent->linked_regs = linked_regs;
+ return 0;
+ }
+
+@@ -3493,6 +3575,7 @@ static int push_jmp_history(struct bpf_verifier_env *env, struct bpf_verifier_st
+ p->idx = env->insn_idx;
+ p->prev_idx = env->prev_insn_idx;
+ p->flags = insn_flags;
++ p->linked_regs = linked_regs;
+ cur->jmp_history_cnt = cnt;
+ env->cur_hist_ent = p;
+
+@@ -3668,6 +3751,11 @@ static inline bool bt_is_reg_set(struct backtrack_state *bt, u32 reg)
+ return bt->reg_masks[bt->frame] & (1 << reg);
+ }
+
++static inline bool bt_is_frame_reg_set(struct backtrack_state *bt, u32 frame, u32 reg)
++{
++ return bt->reg_masks[frame] & (1 << reg);
++}
++
+ static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u32 slot)
+ {
+ return bt->stack_masks[frame] & (1ull << slot);
+@@ -3717,6 +3805,42 @@ static void fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask)
+ }
+ }
+
++/* If any register R in hist->linked_regs is marked as precise in bt,
++ * do bt_set_frame_{reg,slot}(bt, R) for all registers in hist->linked_regs.
++ */
++static void bt_sync_linked_regs(struct backtrack_state *bt, struct bpf_jmp_history_entry *hist)
++{
++ struct linked_regs linked_regs;
++ bool some_precise = false;
++ int i;
++
++ if (!hist || hist->linked_regs == 0)
++ return;
++
++ linked_regs_unpack(hist->linked_regs, &linked_regs);
++ for (i = 0; i < linked_regs.cnt; ++i) {
++ struct linked_reg *e = &linked_regs.entries[i];
++
++ if ((e->is_reg && bt_is_frame_reg_set(bt, e->frameno, e->regno)) ||
++ (!e->is_reg && bt_is_frame_slot_set(bt, e->frameno, e->spi))) {
++ some_precise = true;
++ break;
++ }
++ }
++
++ if (!some_precise)
++ return;
++
++ for (i = 0; i < linked_regs.cnt; ++i) {
++ struct linked_reg *e = &linked_regs.entries[i];
++
++ if (e->is_reg)
++ bt_set_frame_reg(bt, e->frameno, e->regno);
++ else
++ bt_set_frame_slot(bt, e->frameno, e->spi);
++ }
++}
++
+ static bool calls_callback(struct bpf_verifier_env *env, int insn_idx);
+
+ /* For given verifier state backtrack_insn() is called from the last insn to
+@@ -3756,6 +3880,12 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx,
+ print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
+ }
+
++ /* If there is a history record that some registers gained range at this insn,
++ * propagate precision marks to those registers, so that bt_is_reg_set()
++ * accounts for these registers.
++ */
++ bt_sync_linked_regs(bt, hist);
++
+ if (class == BPF_ALU || class == BPF_ALU64) {
+ if (!bt_is_reg_set(bt, dreg))
+ return 0;
+@@ -3985,7 +4115,8 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx,
+ */
+ bt_set_reg(bt, dreg);
+ bt_set_reg(bt, sreg);
+- /* else dreg <cond> K
++ } else if (BPF_SRC(insn->code) == BPF_K) {
++ /* dreg <cond> K
+ * Only dreg still needs precision before
+ * this insn, so for the K-based conditional
+ * there is nothing new to be marked.
+@@ -4003,6 +4134,10 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx,
+ /* to be analyzed */
+ return -ENOTSUPP;
+ }
++ /* Propagate precision marks to linked registers, to account for
++ * registers marked as precise in this function.
++ */
++ bt_sync_linked_regs(bt, hist);
+ return 0;
+ }
+
+@@ -4354,7 +4489,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)
+
+ /* If some register with scalar ID is marked as precise,
+ * make sure that all registers sharing this ID are also precise.
+- * This is needed to estimate effect of find_equal_scalars().
++ * This is needed to estimate effect of sync_linked_regs().
+ * Do this at the last instruction of each state,
+ * bpf_reg_state::id fields are valid for these instructions.
+ *
+@@ -4368,7 +4503,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)
+ * ...
+ * --- state #1 {r1.id = A, r2.id = A} ---
+ * ...
+- * if (r2 > 10) goto exit; // find_equal_scalars() assigns range to r1
++ * if (r2 > 10) goto exit; // sync_linked_regs() assigns range to r1
+ * ...
+ * --- state #2 {r1.id = A, r2.id = A} ---
+ * r3 = r10
+@@ -4736,7 +4871,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
+ }
+
+ if (insn_flags)
+- return push_jmp_history(env, env->cur_state, insn_flags);
++ return push_jmp_history(env, env->cur_state, insn_flags, 0);
+ return 0;
+ }
+
+@@ -5032,7 +5167,7 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
+ insn_flags = 0; /* we are not restoring spilled register */
+ }
+ if (insn_flags)
+- return push_jmp_history(env, env->cur_state, insn_flags);
++ return push_jmp_history(env, env->cur_state, insn_flags, 0);
+ return 0;
+ }
+
+@@ -13540,7 +13675,7 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
+ ptr_reg = dst_reg;
+ else
+ /* Make sure ID is cleared otherwise dst_reg min/max could be
+- * incorrectly propagated into other registers by find_equal_scalars()
++ * incorrectly propagated into other registers by sync_linked_regs()
+ */
+ dst_reg->id = 0;
+ if (BPF_SRC(insn->code) == BPF_X) {
+@@ -13700,7 +13835,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
+ */
+ if (need_id)
+ /* Assign src and dst registers the same ID
+- * that will be used by find_equal_scalars()
++ * that will be used by sync_linked_regs()
+ * to propagate min/max range.
+ */
+ src_reg->id = ++env->id_gen;
+@@ -13746,7 +13881,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
+ copy_register_state(dst_reg, src_reg);
+ /* Make sure ID is cleared if src_reg is not in u32
+ * range otherwise dst_reg min/max could be incorrectly
+- * propagated into src_reg by find_equal_scalars()
++ * propagated into src_reg by sync_linked_regs()
+ */
+ if (!is_src_reg_u32)
+ dst_reg->id = 0;
+@@ -14564,19 +14699,78 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
+ return true;
+ }
+
+-static void find_equal_scalars(struct bpf_verifier_state *vstate,
+- struct bpf_reg_state *known_reg)
++static void __collect_linked_regs(struct linked_regs *reg_set, struct bpf_reg_state *reg,
++ u32 id, u32 frameno, u32 spi_or_reg, bool is_reg)
+ {
+- struct bpf_func_state *state;
++ struct linked_reg *e;
++
++ if (reg->type != SCALAR_VALUE || reg->id != id)
++ return;
++
++ e = linked_regs_push(reg_set);
++ if (e) {
++ e->frameno = frameno;
++ e->is_reg = is_reg;
++ e->regno = spi_or_reg;
++ } else {
++ reg->id = 0;
++ }
++}
++
++/* For all R being scalar registers or spilled scalar registers
++ * in verifier state, save R in linked_regs if R->id == id.
++ * If there are too many Rs sharing same id, reset id for leftover Rs.
++ */
++static void collect_linked_regs(struct bpf_verifier_state *vstate, u32 id,
++ struct linked_regs *linked_regs)
++{
++ struct bpf_func_state *func;
+ struct bpf_reg_state *reg;
++ int i, j;
+
+- bpf_for_each_reg_in_vstate(vstate, state, reg, ({
+- if (reg->type == SCALAR_VALUE && reg->id == known_reg->id) {
++ for (i = vstate->curframe; i >= 0; i--) {
++ func = vstate->frame[i];
++ for (j = 0; j < BPF_REG_FP; j++) {
++ reg = &func->regs[j];
++ __collect_linked_regs(linked_regs, reg, id, i, j, true);
++ }
++ for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
++ if (!is_spilled_reg(&func->stack[j]))
++ continue;
++ reg = &func->stack[j].spilled_ptr;
++ __collect_linked_regs(linked_regs, reg, id, i, j, false);
++ }
++ }
++
++ if (linked_regs->cnt == 1)
++ linked_regs->cnt = 0;
++}
++
++/* For all R in linked_regs, copy known_reg range into R
++ * if R->id == known_reg->id.
++ */
++static void sync_linked_regs(struct bpf_verifier_state *vstate, struct bpf_reg_state *known_reg,
++ struct linked_regs *linked_regs)
++{
++ struct bpf_reg_state *reg;
++ struct linked_reg *e;
++ int i;
++
++ for (i = 0; i < linked_regs->cnt; ++i) {
++ e = &linked_regs->entries[i];
++ reg = e->is_reg ? &vstate->frame[e->frameno]->regs[e->regno]
++ : &vstate->frame[e->frameno]->stack[e->spi].spilled_ptr;
++ if (reg->type != SCALAR_VALUE || reg == known_reg)
++ continue;
++ if (reg->id != known_reg->id)
++ continue;
++ {
+ s32 saved_subreg_def = reg->subreg_def;
++
+ copy_register_state(reg, known_reg);
+ reg->subreg_def = saved_subreg_def;
+ }
+- }));
++ }
+ }
+
+ static int check_cond_jmp_op(struct bpf_verifier_env *env,
+@@ -14587,6 +14781,7 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
+ struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
+ struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL;
+ struct bpf_reg_state *eq_branch_regs;
++ struct linked_regs linked_regs = {};
+ u8 opcode = BPF_OP(insn->code);
+ bool is_jmp32;
+ int pred = -1;
+@@ -14704,6 +14899,21 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
+ return 0;
+ }
+
++ /* Push scalar registers sharing same ID to jump history,
++ * do this before creating 'other_branch', so that both
++ * 'this_branch' and 'other_branch' share this history
++ * if parent state is created.
++ */
++ if (BPF_SRC(insn->code) == BPF_X && src_reg->type == SCALAR_VALUE && src_reg->id)
++ collect_linked_regs(this_branch, src_reg->id, &linked_regs);
++ if (dst_reg->type == SCALAR_VALUE && dst_reg->id)
++ collect_linked_regs(this_branch, dst_reg->id, &linked_regs);
++ if (linked_regs.cnt > 0) {
++ err = push_jmp_history(env, this_branch, 0, linked_regs_pack(&linked_regs));
++ if (err)
++ return err;
++ }
++
+ other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx,
+ false);
+ if (!other_branch)
+@@ -14746,8 +14956,9 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
+ src_reg, dst_reg, opcode);
+ if (src_reg->id &&
+ !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) {
+- find_equal_scalars(this_branch, src_reg);
+- find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]);
++ sync_linked_regs(this_branch, src_reg, &linked_regs);
++ sync_linked_regs(other_branch, &other_branch_regs[insn->src_reg],
++ &linked_regs);
+ }
+
+ }
+@@ -14759,8 +14970,9 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
+
+ if (dst_reg->type == SCALAR_VALUE && dst_reg->id &&
+ !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) {
+- find_equal_scalars(this_branch, dst_reg);
+- find_equal_scalars(other_branch, &other_branch_regs[insn->dst_reg]);
++ sync_linked_regs(this_branch, dst_reg, &linked_regs);
++ sync_linked_regs(other_branch, &other_branch_regs[insn->dst_reg],
++ &linked_regs);
+ }
+
+ /* if one pointer register is compared to another pointer
+@@ -16182,7 +16394,7 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
+ *
+ * First verification path is [1-6]:
+ * - at (4) same bpf_reg_state::id (b) would be assigned to r6 and r7;
+- * - at (5) r6 would be marked <= X, find_equal_scalars() would also mark
++ * - at (5) r6 would be marked <= X, sync_linked_regs() would also mark
+ * r7 <= X, because r6 and r7 share same id.
+ * Next verification path is [1-4, 6].
+ *
+@@ -16915,7 +17127,7 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
+ * the current state.
+ */
+ if (is_jmp_point(env, env->insn_idx))
+- err = err ? : push_jmp_history(env, cur, 0);
++ err = err ? : push_jmp_history(env, cur, 0, 0);
+ err = err ? : propagate_precision(env, &sl->state);
+ if (err)
+ return err;
+@@ -17181,7 +17393,7 @@ static int do_check(struct bpf_verifier_env *env)
+ }
+
+ if (is_jmp_point(env, env->insn_idx)) {
+- err = push_jmp_history(env, state, 0);
++ err = push_jmp_history(env, state, 0, 0);
+ if (err)
+ return err;
+ }
+diff --git a/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c b/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c
+index 4b8b0f45d17d71..a188e26f04da70 100644
+--- a/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c
++++ b/tools/testing/selftests/bpf/progs/verifier_subprog_precision.c
+@@ -141,7 +141,7 @@ __msg("mark_precise: frame0: last_idx 14 first_idx 9")
+ __msg("mark_precise: frame0: regs=r6 stack= before 13: (bf) r1 = r7")
+ __msg("mark_precise: frame0: regs=r6 stack= before 12: (27) r6 *= 4")
+ __msg("mark_precise: frame0: regs=r6 stack= before 11: (25) if r6 > 0x3 goto pc+4")
+-__msg("mark_precise: frame0: regs=r6 stack= before 10: (bf) r6 = r0")
++__msg("mark_precise: frame0: regs=r0,r6 stack= before 10: (bf) r6 = r0")
+ __msg("mark_precise: frame0: regs=r0 stack= before 9: (85) call bpf_loop")
+ /* State entering callback body popped from states stack */
+ __msg("from 9 to 17: frame1:")
+--
+2.53.0
+
--- /dev/null
+From b441300fba3444317dcda28f92e3a11753b0e050 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Mon, 15 Jun 2026 00:58:40 +0800
+Subject: selftests/bpf: Tests for per-insn sync_linked_regs() precision
+ tracking
+
+From: Eduard Zingerman <eddyz87@gmail.com>
+
+[ Upstream commit bebc17b1c03b224a0b4aec6a171815e39f8ba9bc ]
+
+Add a few test cases to verify precision tracking for scalars gaining
+range because of sync_linked_regs():
+- check what happens when more than 6 registers might gain range in
+ sync_linked_regs();
+- check if precision is propagated correctly when operand of
+ conditional jump gained range in sync_linked_regs() and one of
+ linked registers is marked precise;
+- check if precision is propagated correctly when operand of
+ conditional jump gained range in sync_linked_regs() and a
+ other-linked operand of the conditional jump is marked precise;
+- add a minimized reproducer for precision tracking bug reported in [0];
+- Check that mark_chain_precision() for one of the conditional jump
+ operands does not trigger equal scalars precision propagation.
+
+[0] https://lore.kernel.org/bpf/CAEf4BzZ0xidVCqB47XnkXcNhkPWF6_nTV7yt+_Lf0kcFEut2Mg@mail.gmail.com/
+
+Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
+Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
+Link: https://lore.kernel.org/bpf/20240718202357.1746514-4-eddyz87@gmail.com
+[ zhenzhong: keep the linked_regs_broken_link_2 reject check, but
+ drop the mark_precise log expectations because 6.6.y does not derive
+ the scalar-vs-scalar range for that non-constant JMP_X comparison. ]
+Signed-off-by: Zhenzhong Wu <jt26wzz@gmail.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ .../selftests/bpf/progs/verifier_scalar_ids.c | 162 ++++++++++++++++++
+ 1 file changed, 162 insertions(+)
+
+diff --git a/tools/testing/selftests/bpf/progs/verifier_scalar_ids.c b/tools/testing/selftests/bpf/progs/verifier_scalar_ids.c
+index f70392bf696c62..2eb85eb3a06ccb 100644
+--- a/tools/testing/selftests/bpf/progs/verifier_scalar_ids.c
++++ b/tools/testing/selftests/bpf/progs/verifier_scalar_ids.c
+@@ -47,6 +47,72 @@ __naked void linked_regs_bpf_k(void)
+ : __clobber_all);
+ }
+
++/* Registers r{0,1,2} share same ID when 'if r1 > ...' insn is processed,
++ * check that verifier marks r{1,2} as precise while backtracking
++ * 'if r1 > ...' with r0 already marked.
++ */
++SEC("socket")
++__success __log_level(2)
++__flag(BPF_F_TEST_STATE_FREQ)
++__msg("frame0: regs=r0 stack= before 5: (2d) if r1 > r3 goto pc+0")
++__msg("frame0: parent state regs=r0,r1,r2,r3 stack=:")
++__msg("frame0: regs=r0,r1,r2,r3 stack= before 4: (b7) r3 = 7")
++__naked void linked_regs_bpf_x_src(void)
++{
++ asm volatile (
++ /* r0 = random number up to 0xff */
++ "call %[bpf_ktime_get_ns];"
++ "r0 &= 0xff;"
++ /* tie r0.id == r1.id == r2.id */
++ "r1 = r0;"
++ "r2 = r0;"
++ "r3 = 7;"
++ "if r1 > r3 goto +0;"
++ /* force r0 to be precise, this eventually marks r1 and r2 as
++ * precise as well because of shared IDs
++ */
++ "r4 = r10;"
++ "r4 += r0;"
++ "r0 = 0;"
++ "exit;"
++ :
++ : __imm(bpf_ktime_get_ns)
++ : __clobber_all);
++}
++
++/* Registers r{0,1,2} share same ID when 'if r1 > r3' insn is processed,
++ * check that verifier marks r{0,1,2} as precise while backtracking
++ * 'if r1 > r3' with r3 already marked.
++ */
++SEC("socket")
++__success __log_level(2)
++__flag(BPF_F_TEST_STATE_FREQ)
++__msg("frame0: regs=r3 stack= before 5: (2d) if r1 > r3 goto pc+0")
++__msg("frame0: parent state regs=r0,r1,r2,r3 stack=:")
++__msg("frame0: regs=r0,r1,r2,r3 stack= before 4: (b7) r3 = 7")
++__naked void linked_regs_bpf_x_dst(void)
++{
++ asm volatile (
++ /* r0 = random number up to 0xff */
++ "call %[bpf_ktime_get_ns];"
++ "r0 &= 0xff;"
++ /* tie r0.id == r1.id == r2.id */
++ "r1 = r0;"
++ "r2 = r0;"
++ "r3 = 7;"
++ "if r1 > r3 goto +0;"
++ /* force r0 to be precise, this eventually marks r1 and r2 as
++ * precise as well because of shared IDs
++ */
++ "r4 = r10;"
++ "r4 += r3;"
++ "r0 = 0;"
++ "exit;"
++ :
++ : __imm(bpf_ktime_get_ns)
++ : __clobber_all);
++}
++
+ /* Same as linked_regs_bpf_k, but break one of the
+ * links, note that r1 is absent from regs=... in __msg below.
+ */
+@@ -280,6 +346,102 @@ __naked void precision_two_ids(void)
+ : __clobber_all);
+ }
+
++SEC("socket")
++__success __log_level(2)
++__flag(BPF_F_TEST_STATE_FREQ)
++/* check thar r0 and r6 have different IDs after 'if',
++ * collect_linked_regs() can't tie more than 6 registers for a single insn.
++ */
++__msg("8: (25) if r0 > 0x7 goto pc+0 ; R0=scalar(id=1")
++__msg("9: (bf) r6 = r6 ; R6_w=scalar(id=2")
++/* check that r{0-5} are marked precise after 'if' */
++__msg("frame0: regs=r0 stack= before 8: (25) if r0 > 0x7 goto pc+0")
++__msg("frame0: parent state regs=r0,r1,r2,r3,r4,r5 stack=:")
++__naked void linked_regs_too_many_regs(void)
++{
++ asm volatile (
++ /* r0 = random number up to 0xff */
++ "call %[bpf_ktime_get_ns];"
++ "r0 &= 0xff;"
++ /* tie r{0-6} IDs */
++ "r1 = r0;"
++ "r2 = r0;"
++ "r3 = r0;"
++ "r4 = r0;"
++ "r5 = r0;"
++ "r6 = r0;"
++ /* propagate range for r{0-6} */
++ "if r0 > 7 goto +0;"
++ /* make r6 appear in the log */
++ "r6 = r6;"
++ /* force r0 to be precise,
++ * this would cause r{0-4} to be precise because of shared IDs
++ */
++ "r7 = r10;"
++ "r7 += r0;"
++ "r0 = 0;"
++ "exit;"
++ :
++ : __imm(bpf_ktime_get_ns)
++ : __clobber_all);
++}
++
++SEC("socket")
++__failure __log_level(2)
++__flag(BPF_F_TEST_STATE_FREQ)
++__msg("div by zero")
++__naked void linked_regs_broken_link_2(void)
++{
++ asm volatile (
++ "call %[bpf_get_prandom_u32];"
++ "r7 = r0;"
++ "r8 = r0;"
++ "call %[bpf_get_prandom_u32];"
++ "if r0 > 1 goto +0;"
++ /* r7.id == r8.id,
++ * thus r7 precision implies r8 precision,
++ * which implies r0 precision because of the conditional below.
++ */
++ "if r8 >= r0 goto 1f;"
++ /* break id relation between r7 and r8 */
++ "r8 += r8;"
++ /* make r7 precise */
++ "if r7 == 0 goto 1f;"
++ "r0 /= 0;"
++"1:"
++ "r0 = 42;"
++ "exit;"
++ :
++ : __imm(bpf_get_prandom_u32)
++ : __clobber_all);
++}
++
++/* Check that mark_chain_precision() for one of the conditional jump
++ * operands does not trigger equal scalars precision propagation.
++ */
++SEC("socket")
++__success __log_level(2)
++__msg("3: (25) if r1 > 0x100 goto pc+0")
++__msg("frame0: regs=r1 stack= before 2: (bf) r1 = r0")
++__naked void cjmp_no_linked_regs_trigger(void)
++{
++ asm volatile (
++ /* r0 = random number up to 0xff */
++ "call %[bpf_ktime_get_ns];"
++ "r0 &= 0xff;"
++ /* tie r0.id == r1.id */
++ "r1 = r0;"
++ /* the jump below would be predicted, thus r1 would be marked precise,
++ * this should not imply precision mark for r0
++ */
++ "if r1 > 256 goto +0;"
++ "r0 = 0;"
++ "exit;"
++ :
++ : __imm(bpf_ktime_get_ns)
++ : __clobber_all);
++}
++
+ /* Verify that check_ids() is used by regsafe() for scalars.
+ *
+ * r9 = ... some pointer with range X ...
+--
+2.53.0
+
--- /dev/null
+From 09c7e03e369a36c704605b17be17ab4614bb3780 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Mon, 15 Jun 2026 00:58:41 +0800
+Subject: selftests/bpf: Update comments find_equal_scalars->sync_linked_regs
+
+From: Eduard Zingerman <eddyz87@gmail.com>
+
+[ Upstream commit cfbf25481d6dec0089c99c9d33a2ea634fe8f008 ]
+
+find_equal_scalars() is renamed to sync_linked_regs(),
+this commit updates existing references in the selftests comments.
+
+Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
+Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
+Link: https://lore.kernel.org/bpf/20240718202357.1746514-5-eddyz87@gmail.com
+[ zhenzhong: only two pre-existing comments still needed updating in 6.6.y. ]
+Signed-off-by: Zhenzhong Wu <jt26wzz@gmail.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ tools/testing/selftests/bpf/progs/verifier_spill_fill.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
+index 1f71f596d33f8b..07a2527a8f47a7 100644
+--- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
++++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
+@@ -392,7 +392,7 @@ __naked void spill_32bit_of_64bit_fail(void)
+ *(u32*)(r10 - 8) = r1; \
+ /* 32-bit fill r2 from stack. */ \
+ r2 = *(u32*)(r10 - 8); \
+- /* Compare r2 with another register to trigger find_equal_scalars.\
++ /* Compare r2 with another register to trigger sync_linked_regs.\
+ * Having one random bit is important here, otherwise the verifier cuts\
+ * the corners. If the ID was mistakenly preserved on spill, this would\
+ * cause the verifier to think that r1 is also equal to zero in one of\
+@@ -431,7 +431,7 @@ __naked void spill_16bit_of_32bit_fail(void)
+ *(u16*)(r10 - 8) = r1; \
+ /* 16-bit fill r2 from stack. */ \
+ r2 = *(u16*)(r10 - 8); \
+- /* Compare r2 with another register to trigger find_equal_scalars.\
++ /* Compare r2 with another register to trigger sync_linked_regs.\
+ * Having one random bit is important here, otherwise the verifier cuts\
+ * the corners. If the ID was mistakenly preserved on spill, this would\
+ * cause the verifier to think that r1 is also equal to zero in one of\
+--
+2.53.0
+
mmc-litex_mmc-use-div_round_up-for-more-accurate-clock-calculation.patch
kvm-don-t-warn-if-memory-is-dirtied-without-a-vcpu-when-the-vm-is-dying.patch
drm-i915-gem-fix-phys-bo-pread-pwrite-with-offset.patch
+bpf-track-equal-scalars-history-on-per-instruction-l.patch
+bpf-remove-mark_precise_scalar_ids.patch
+selftests-bpf-tests-for-per-insn-sync_linked_regs-pr.patch
+selftests-bpf-update-comments-find_equal_scalars-syn.patch
projects / thirdparty / kernel / stable-queue.git / commitdiff
