Merge tag 'bpf-next-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Pull bpf updates from Alexei Starovoitov:

 - Introduce '__attribute__((bpf_fastcall))' for helpers and kfuncs with
   corresponding support in LLVM.

   It is similar to existing 'no_caller_saved_registers' attribute in
   GCC/LLVM with a provision for backward compatibility. It allows
   compilers generate more efficient BPF code assuming the verifier or
   JITs will inline or partially inline a helper/kfunc with such
   attribute. bpf_cast_to_kern_ctx, bpf_rdonly_cast,
   bpf_get_smp_processor_id are the first set of such helpers.

 - Harden and extend ELF build ID parsing logic.

   When called from sleepable context the relevants parts of ELF file
   will be read to find and fetch .note.gnu.build-id information. Also
   harden the logic to avoid TOCTOU, overflow, out-of-bounds problems.

 - Improvements and fixes for sched-ext:
    - Allow passing BPF iterators as kfunc arguments
    - Make the pointer returned from iter_next method trusted
    - Fix x86 JIT convergence issue due to growing/shrinking conditional
      jumps in variable length encoding

 - BPF_LSM related:
    - Introduce few VFS kfuncs and consolidate them in
      fs/bpf_fs_kfuncs.c
    - Enforce correct range of return values from certain LSM hooks
    - Disallow attaching to other LSM hooks

 - Prerequisite work for upcoming Qdisc in BPF:
    - Allow kptrs in program provided structs
    - Support for gen_epilogue in verifier_ops

 - Important fixes:
    - Fix uprobe multi pid filter check
    - Fix bpf_strtol and bpf_strtoul helpers
    - Track equal scalars history on per-instruction level
    - Fix tailcall hierarchy on x86 and arm64
    - Fix signed division overflow to prevent INT_MIN/-1 trap on x86
    - Fix get kernel stack in BPF progs attached to tracepoint:syscall

 - Selftests:
    - Add uprobe bench/stress tool
    - Generate file dependencies to drastically improve re-build time
    - Match JIT-ed and BPF asm with __xlated/__jited keywords
    - Convert older tests to test_progs framework
    - Add support for RISC-V
    - Few fixes when BPF programs are compiled with GCC-BPF backend
      (support for GCC-BPF in BPF CI is ongoing in parallel)
    - Add traffic monitor
    - Enable cross compile and musl libc

* tag 'bpf-next-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (260 commits)
  btf: require pahole 1.21+ for DEBUG_INFO_BTF with default DWARF version
  btf: move pahole check in scripts/link-vmlinux.sh to lib/Kconfig.debug
  btf: remove redundant CONFIG_BPF test in scripts/link-vmlinux.sh
  bpf: Call the missed kfree() when there is no special field in btf
  bpf: Call the missed btf_record_free() when map creation fails
  selftests/bpf: Add a test case to write mtu result into .rodata
  selftests/bpf: Add a test case to write strtol result into .rodata
  selftests/bpf: Rename ARG_PTR_TO_LONG test description
  selftests/bpf: Fix ARG_PTR_TO_LONG {half-,}uninitialized test
  bpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error
  bpf: Improve check_raw_mode_ok test for MEM_UNINIT-tagged types
  bpf: Fix helper writes to read-only maps
  bpf: Remove truncation test in bpf_strtol and bpf_strtoul helpers
  bpf: Fix bpf_strtol and bpf_strtoul helpers for 32bit
  selftests/bpf: Add tests for sdiv/smod overflow cases
  bpf: Fix a sdiv overflow issue
  libbpf: Add bpf_object__token_fd accessor
  docs/bpf: Add missing BPF program types to docs
  docs/bpf: Add constant values for linkages
  bpf: Use fake pt_regs when doing bpf syscall tracepoint tracing
  ...

1 files changed, 131 insertions, 30 deletions

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index d25d81c8ecc0..06b080b61aa5 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -64,6 +64,56 @@ static bool is_imm8(int value)
 	return value <= 127 && value >= -128;
 }
 
+/*
+ * Let us limit the positive offset to be <= 123.
+ * This is to ensure eventual jit convergence For the following patterns:
+ * ...
+ * pass4, final_proglen=4391:
+ *   ...
+ *   20e:    48 85 ff                test   rdi,rdi
+ *   211:    74 7d                   je     0x290
+ *   213:    48 8b 77 00             mov    rsi,QWORD PTR [rdi+0x0]
+ *   ...
+ *   289:    48 85 ff                test   rdi,rdi
+ *   28c:    74 17                   je     0x2a5
+ *   28e:    e9 7f ff ff ff          jmp    0x212
+ *   293:    bf 03 00 00 00          mov    edi,0x3
+ * Note that insn at 0x211 is 2-byte cond jump insn for offset 0x7d (-125)
+ * and insn at 0x28e is 5-byte jmp insn with offset -129.
+ *
+ * pass5, final_proglen=4392:
+ *   ...
+ *   20e:    48 85 ff                test   rdi,rdi
+ *   211:    0f 84 80 00 00 00       je     0x297
+ *   217:    48 8b 77 00             mov    rsi,QWORD PTR [rdi+0x0]
+ *   ...
+ *   28d:    48 85 ff                test   rdi,rdi
+ *   290:    74 1a                   je     0x2ac
+ *   292:    eb 84                   jmp    0x218
+ *   294:    bf 03 00 00 00          mov    edi,0x3
+ * Note that insn at 0x211 is 6-byte cond jump insn now since its offset
+ * becomes 0x80 based on previous round (0x293 - 0x213 = 0x80).
+ * At the same time, insn at 0x292 is a 2-byte insn since its offset is
+ * -124.
+ *
+ * pass6 will repeat the same code as in pass4 and this will prevent
+ * eventual convergence.
+ *
+ * To fix this issue, we need to break je (2->6 bytes) <-> jmp (5->2 bytes)
+ * cycle in the above. In the above example je offset <= 0x7c should work.
+ *
+ * For other cases, je <-> je needs offset <= 0x7b to avoid no convergence
+ * issue. For jmp <-> je and jmp <-> jmp cases, jmp offset <= 0x7c should
+ * avoid no convergence issue.
+ *
+ * Overall, let us limit the positive offset for 8bit cond/uncond jmp insn
+ * to maximum 123 (0x7b). This way, the jit pass can eventually converge.
+ */
+static bool is_imm8_jmp_offset(int value)
+{
+	return value <= 123 && value >= -128;
+}
+
 static bool is_simm32(s64 value)
 {
 	return value == (s64)(s32)value;
@@ -273,7 +323,7 @@ struct jit_context {
 /* Number of bytes emit_patch() needs to generate instructions */
 #define X86_PATCH_SIZE		5
 /* Number of bytes that will be skipped on tailcall */
-#define X86_TAIL_CALL_OFFSET	(11 + ENDBR_INSN_SIZE)
+#define X86_TAIL_CALL_OFFSET	(12 + ENDBR_INSN_SIZE)
 
 static void push_r12(u8 **pprog)
 {
@@ -403,6 +453,37 @@ static void emit_cfi(u8 **pprog, u32 hash)
 	*pprog = prog;
 }
 
+static void emit_prologue_tail_call(u8 **pprog, bool is_subprog)
+{
+	u8 *prog = *pprog;
+
+	if (!is_subprog) {
+		/* cmp rax, MAX_TAIL_CALL_CNT */
+		EMIT4(0x48, 0x83, 0xF8, MAX_TAIL_CALL_CNT);
+		EMIT2(X86_JA, 6);        /* ja 6 */
+		/* rax is tail_call_cnt if <= MAX_TAIL_CALL_CNT.
+		 * case1: entry of main prog.
+		 * case2: tail callee of main prog.
+		 */
+		EMIT1(0x50);             /* push rax */
+		/* Make rax as tail_call_cnt_ptr. */
+		EMIT3(0x48, 0x89, 0xE0); /* mov rax, rsp */
+		EMIT2(0xEB, 1);          /* jmp 1 */
+		/* rax is tail_call_cnt_ptr if > MAX_TAIL_CALL_CNT.
+		 * case: tail callee of subprog.
+		 */
+		EMIT1(0x50);             /* push rax */
+		/* push tail_call_cnt_ptr */
+		EMIT1(0x50);             /* push rax */
+	} else { /* is_subprog */
+		/* rax is tail_call_cnt_ptr. */
+		EMIT1(0x50);             /* push rax */
+		EMIT1(0x50);             /* push rax */
+	}
+
+	*pprog = prog;
+}
+
 /*
  * Emit x86-64 prologue code for BPF program.
  * bpf_tail_call helper will skip the first X86_TAIL_CALL_OFFSET bytes
@@ -424,10 +505,10 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf,
 			/* When it's the entry of the whole tailcall context,
 			 * zeroing rax means initialising tail_call_cnt.
 			 */
-			EMIT2(0x31, 0xC0); /* xor eax, eax */
+			EMIT3(0x48, 0x31, 0xC0); /* xor rax, rax */
 		else
 			/* Keep the same instruction layout. */
-			EMIT2(0x66, 0x90); /* nop2 */
+			emit_nops(&prog, 3);     /* nop3 */
 	}
 	/* Exception callback receives FP as third parameter */
 	if (is_exception_cb) {
@@ -453,7 +534,7 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf,
 	if (stack_depth)
 		EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8));
 	if (tail_call_reachable)
-		EMIT1(0x50);         /* push rax */
+		emit_prologue_tail_call(&prog, is_subprog);
 	*pprog = prog;
 }
 
@@ -589,13 +670,15 @@ static void emit_return(u8 **pprog, u8 *ip)
 	*pprog = prog;
 }
 
+#define BPF_TAIL_CALL_CNT_PTR_STACK_OFF(stack)	(-16 - round_up(stack, 8))
+
 /*
  * Generate the following code:
  *
  * ... bpf_tail_call(void *ctx, struct bpf_array *array, u64 index) ...
  *   if (index >= array->map.max_entries)
  *     goto out;
- *   if (tail_call_cnt++ >= MAX_TAIL_CALL_CNT)
+ *   if ((*tcc_ptr)++ >= MAX_TAIL_CALL_CNT)
  *     goto out;
  *   prog = array->ptrs[index];
  *   if (prog == NULL)
@@ -608,7 +691,7 @@ static void emit_bpf_tail_call_indirect(struct bpf_prog *bpf_prog,
 					u32 stack_depth, u8 *ip,
 					struct jit_context *ctx)
 {
-	int tcc_off = -4 - round_up(stack_depth, 8);
+	int tcc_ptr_off = BPF_TAIL_CALL_CNT_PTR_STACK_OFF(stack_depth);
 	u8 *prog = *pprog, *start = *pprog;
 	int offset;
 
@@ -630,16 +713,14 @@ static void emit_bpf_tail_call_indirect(struct bpf_prog *bpf_prog,
 	EMIT2(X86_JBE, offset);                   /* jbe out */
 
 	/*
-	 * if (tail_call_cnt++ >= MAX_TAIL_CALL_CNT)
+	 * if ((*tcc_ptr)++ >= MAX_TAIL_CALL_CNT)
 	 *	goto out;
 	 */
-	EMIT2_off32(0x8B, 0x85, tcc_off);         /* mov eax, dword ptr [rbp - tcc_off] */
-	EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT);     /* cmp eax, MAX_TAIL_CALL_CNT */
+	EMIT3_off32(0x48, 0x8B, 0x85, tcc_ptr_off); /* mov rax, qword ptr [rbp - tcc_ptr_off] */
+	EMIT4(0x48, 0x83, 0x38, MAX_TAIL_CALL_CNT); /* cmp qword ptr [rax], MAX_TAIL_CALL_CNT */
 
 	offset = ctx->tail_call_indirect_label - (prog + 2 - start);
 	EMIT2(X86_JAE, offset);                   /* jae out */
-	EMIT3(0x83, 0xC0, 0x01);                  /* add eax, 1 */
-	EMIT2_off32(0x89, 0x85, tcc_off);         /* mov dword ptr [rbp - tcc_off], eax */
 
 	/* prog = array->ptrs[index]; */
 	EMIT4_off32(0x48, 0x8B, 0x8C, 0xD6,       /* mov rcx, [rsi + rdx * 8 + offsetof(...)] */
@@ -654,6 +735,9 @@ static void emit_bpf_tail_call_indirect(struct bpf_prog *bpf_prog,
 	offset = ctx->tail_call_indirect_label - (prog + 2 - start);
 	EMIT2(X86_JE, offset);                    /* je out */
 
+	/* Inc tail_call_cnt if the slot is populated. */
+	EMIT4(0x48, 0x83, 0x00, 0x01);            /* add qword ptr [rax], 1 */
+
 	if (bpf_prog->aux->exception_boundary) {
 		pop_callee_regs(&prog, all_callee_regs_used);
 		pop_r12(&prog);
@@ -663,6 +747,11 @@ static void emit_bpf_tail_call_indirect(struct bpf_prog *bpf_prog,
 			pop_r12(&prog);
 	}
 
+	/* Pop tail_call_cnt_ptr. */
+	EMIT1(0x58);                              /* pop rax */
+	/* Pop tail_call_cnt, if it's main prog.
+	 * Pop tail_call_cnt_ptr, if it's subprog.
+	 */
 	EMIT1(0x58);                              /* pop rax */
 	if (stack_depth)
 		EMIT3_off32(0x48, 0x81, 0xC4,     /* add rsp, sd */
@@ -691,21 +780,19 @@ static void emit_bpf_tail_call_direct(struct bpf_prog *bpf_prog,
 				      bool *callee_regs_used, u32 stack_depth,
 				      struct jit_context *ctx)
 {
-	int tcc_off = -4 - round_up(stack_depth, 8);
+	int tcc_ptr_off = BPF_TAIL_CALL_CNT_PTR_STACK_OFF(stack_depth);
 	u8 *prog = *pprog, *start = *pprog;
 	int offset;
 
 	/*
-	 * if (tail_call_cnt++ >= MAX_TAIL_CALL_CNT)
+	 * if ((*tcc_ptr)++ >= MAX_TAIL_CALL_CNT)
 	 *	goto out;
 	 */
-	EMIT2_off32(0x8B, 0x85, tcc_off);             /* mov eax, dword ptr [rbp - tcc_off] */
-	EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT);         /* cmp eax, MAX_TAIL_CALL_CNT */
+	EMIT3_off32(0x48, 0x8B, 0x85, tcc_ptr_off);   /* mov rax, qword ptr [rbp - tcc_ptr_off] */
+	EMIT4(0x48, 0x83, 0x38, MAX_TAIL_CALL_CNT);   /* cmp qword ptr [rax], MAX_TAIL_CALL_CNT */
 
 	offset = ctx->tail_call_direct_label - (prog + 2 - start);
 	EMIT2(X86_JAE, offset);                       /* jae out */
-	EMIT3(0x83, 0xC0, 0x01);                      /* add eax, 1 */
-	EMIT2_off32(0x89, 0x85, tcc_off);             /* mov dword ptr [rbp - tcc_off], eax */
 
 	poke->tailcall_bypass = ip + (prog - start);
 	poke->adj_off = X86_TAIL_CALL_OFFSET;
@@ -715,6 +802,9 @@ static void emit_bpf_tail_call_direct(struct bpf_prog *bpf_prog,
 	emit_jump(&prog, (u8 *)poke->tailcall_target + X86_PATCH_SIZE,
 		  poke->tailcall_bypass);
 
+	/* Inc tail_call_cnt if the slot is populated. */
+	EMIT4(0x48, 0x83, 0x00, 0x01);                /* add qword ptr [rax], 1 */
+
 	if (bpf_prog->aux->exception_boundary) {
 		pop_callee_regs(&prog, all_callee_regs_used);
 		pop_r12(&prog);
@@ -724,6 +814,11 @@ static void emit_bpf_tail_call_direct(struct bpf_prog *bpf_prog,
 			pop_r12(&prog);
 	}
 
+	/* Pop tail_call_cnt_ptr. */
+	EMIT1(0x58);                                  /* pop rax */
+	/* Pop tail_call_cnt, if it's main prog.
+	 * Pop tail_call_cnt_ptr, if it's subprog.
+	 */
 	EMIT1(0x58);                                  /* pop rax */
 	if (stack_depth)
 		EMIT3_off32(0x48, 0x81, 0xC4, round_up(stack_depth, 8));
@@ -1311,9 +1406,11 @@ static void emit_shiftx(u8 **pprog, u32 dst_reg, u8 src_reg, bool is64, u8 op)
 
 #define INSN_SZ_DIFF (((addrs[i] - addrs[i - 1]) - (prog - temp)))
 
-/* mov rax, qword ptr [rbp - rounded_stack_depth - 8] */
-#define RESTORE_TAIL_CALL_CNT(stack)				\
-	EMIT3_off32(0x48, 0x8B, 0x85, -round_up(stack, 8) - 8)
+#define __LOAD_TCC_PTR(off)			\
+	EMIT3_off32(0x48, 0x8B, 0x85, off)
+/* mov rax, qword ptr [rbp - rounded_stack_depth - 16] */
+#define LOAD_TAIL_CALL_CNT_PTR(stack)				\
+	__LOAD_TCC_PTR(BPF_TAIL_CALL_CNT_PTR_STACK_OFF(stack))
 
 static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image,
 		  int oldproglen, struct jit_context *ctx, bool jmp_padding)
@@ -2031,7 +2128,7 @@ populate_extable:
 
 			func = (u8 *) __bpf_call_base + imm32;
 			if (tail_call_reachable) {
-				RESTORE_TAIL_CALL_CNT(bpf_prog->aux->stack_depth);
+				LOAD_TAIL_CALL_CNT_PTR(bpf_prog->aux->stack_depth);
 				ip += 7;
 			}
 			if (!imm32)
@@ -2184,7 +2281,7 @@ emit_cond_jmp:		/* Convert BPF opcode to x86 */
 				return -EFAULT;
 			}
 			jmp_offset = addrs[i + insn->off] - addrs[i];
-			if (is_imm8(jmp_offset)) {
+			if (is_imm8_jmp_offset(jmp_offset)) {
 				if (jmp_padding) {
 					/* To keep the jmp_offset valid, the extra bytes are
 					 * padded before the jump insn, so we subtract the
@@ -2266,7 +2363,7 @@ emit_cond_jmp:		/* Convert BPF opcode to x86 */
 				break;
 			}
 emit_jmp:
-			if (is_imm8(jmp_offset)) {
+			if (is_imm8_jmp_offset(jmp_offset)) {
 				if (jmp_padding) {
 					/* To avoid breaking jmp_offset, the extra bytes
 					 * are padded before the actual jmp insn, so
@@ -2706,6 +2803,10 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
 	return 0;
 }
 
+/* mov rax, qword ptr [rbp - rounded_stack_depth - 8] */
+#define LOAD_TRAMP_TAIL_CALL_CNT_PTR(stack)	\
+	__LOAD_TCC_PTR(-round_up(stack, 8) - 8)
+
 /* Example:
  * __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
  * its 'struct btf_func_model' will be nr_args=2
@@ -2826,7 +2927,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
 	 *                     [ ...        ]
 	 *                     [ stack_arg2 ]
 	 * RBP - arg_stack_off [ stack_arg1 ]
-	 * RSP                 [ tail_call_cnt ] BPF_TRAMP_F_TAIL_CALL_CTX
+	 * RSP                 [ tail_call_cnt_ptr ] BPF_TRAMP_F_TAIL_CALL_CTX
 	 */
 
 	/* room for return value of orig_call or fentry prog */
@@ -2955,10 +3056,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
 		save_args(m, &prog, arg_stack_off, true);
 
 		if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) {
-			/* Before calling the original function, restore the
-			 * tail_call_cnt from stack to rax.
+			/* Before calling the original function, load the
+			 * tail_call_cnt_ptr from stack to rax.
 			 */
-			RESTORE_TAIL_CALL_CNT(stack_size);
+			LOAD_TRAMP_TAIL_CALL_CNT_PTR(stack_size);
 		}
 
 		if (flags & BPF_TRAMP_F_ORIG_STACK) {
@@ -3017,10 +3118,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
 			goto cleanup;
 		}
 	} else if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) {
-		/* Before running the original function, restore the
-		 * tail_call_cnt from stack to rax.
+		/* Before running the original function, load the
+		 * tail_call_cnt_ptr from stack to rax.
 		 */
-		RESTORE_TAIL_CALL_CNT(stack_size);
+		LOAD_TRAMP_TAIL_CALL_CNT_PTR(stack_size);
 	}
 
 	/* restore return value of orig_call or fentry prog back into RAX */