[PATCH 0/3] riscv: Enable LOCKDEP

[PATCH 0/3] riscv: Enable LOCKDEP

[guoren]

From: Guo Ren <guoren@linux.alibaba.com>

Lockdep is needed by proving the spinlocks and rwlocks. To suupport
it, we need fixup TRACE_IRQFLAGS_SUPPORT in kernel/entry.S. This
patch follow Documentation/irqflags-tracing.txt.

And there are 2 bugs block the lockdep implementation.

Guo Ren (2):
  riscv: Fixup static_obj() fail
  riscv: Enable LOCKDEP_SUPPORT & fixup TRACE_IRQFLAGS_SUPPORT

Zong Li (1):
  riscv: Fixup lockdep_assert_held with wrong param cpu_running

 arch/riscv/Kconfig              |  3 +++
 arch/riscv/kernel/entry.S       | 41 ++++++++++++++++++++++++++++++++++++++++-
 arch/riscv/kernel/smpboot.c     |  1 -
 arch/riscv/kernel/vmlinux.lds.S |  2 +-
 4 files changed, 44 insertions(+), 3 deletions(-)

-- 
2.7.4

[PATCH 1/3] riscv: Fixup static_obj() fail

[guoren]

From: Guo Ren <guoren@linux.alibaba.com>

When enable LOCKDEP, static_obj() will cause error. Because some
__initdata static variables is before _stext:

static int static_obj(const void *obj)
{
        unsigned long start = (unsigned long) &_stext,
                      end   = (unsigned long) &_end,
                      addr  = (unsigned long) obj;

        /*
         * static variable?
         */
        if ((addr >= start) && (addr < end))
                return 1;

[    0.067192] INFO: trying to register non-static key.
[    0.067325] the code is fine but needs lockdep annotation.
[    0.067449] turning off the locking correctness validator.
[    0.067718] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-rc7-dirty #44
[    0.067945] Call Trace:
[    0.068369] [<ffffffe00020323c>] walk_stackframe+0x0/0xa4
[    0.068506] [<ffffffe000203422>] show_stack+0x2a/0x34
[    0.068631] [<ffffffe000521e4e>] dump_stack+0x94/0xca
[    0.068757] [<ffffffe000255a4e>] register_lock_class+0x5b8/0x5bc
[    0.068969] [<ffffffe000255abe>] __lock_acquire+0x6c/0x1d5c
[    0.069101] [<ffffffe0002550fe>] lock_acquire+0xae/0x312
[    0.069228] [<ffffffe000989a8e>] _raw_spin_lock_irqsave+0x40/0x5a
[    0.069357] [<ffffffe000247c64>] complete+0x1e/0x50
[    0.069479] [<ffffffe000984c38>] rest_init+0x1b0/0x28a
[    0.069660] [<ffffffe0000016a2>] 0xffffffe0000016a2
[    0.069779] [<ffffffe000001b84>] 0xffffffe000001b84
[    0.069953] [<ffffffe000001092>] 0xffffffe000001092

static __initdata DECLARE_COMPLETION(kthreadd_done);

noinline void __ref rest_init(void)
{
	...
	complete(&kthreadd_done);

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
 arch/riscv/kernel/vmlinux.lds.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 0339b6b..bf3f34d 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -22,6 +22,7 @@ SECTIONS
 	/* Beginning of code and text segment */
 	. = LOAD_OFFSET;
 	_start = .;
+	_stext = .;
 	HEAD_TEXT_SECTION
 	. = ALIGN(PAGE_SIZE);
 
@@ -49,7 +50,6 @@ SECTIONS
 	. = ALIGN(SECTION_ALIGN);
 	.text : {
 		_text = .;
-		_stext = .;
 		TEXT_TEXT
 		SCHED_TEXT
 		CPUIDLE_TEXT
-- 
2.7.4

[PATCH 2/3] riscv: Fixup lockdep_assert_held with wrong param cpu_running

[guoren]

From: Zong Li <zong.li@sifive.com>

The cpu_running is not a lock-class, it lacks the dep_map member in
completion. It causes the error as follow:

arch/riscv/kernel/smpboot.c: In function '__cpu_up':
./include/linux/lockdep.h:364:52: error: 'struct completion' has no member named 'dep_map'
  364 | #define lockdep_is_held(lock)  lock_is_held(&(lock)->dep_map)
      |                                                    ^~
./include/asm-generic/bug.h:113:25: note: in definition of macro 'WARN_ON'
  113 |  int __ret_warn_on = !!(condition);    \
      |                         ^~~~~~~~~
./include/linux/lockdep.h:390:27: note: in expansion of macro 'lockdep_is_held'
  390 |   WARN_ON(debug_locks && !lockdep_is_held(l)); \
      |                           ^~~~~~~~~~~~~~~
arch/riscv/kernel/smpboot.c:118:2: note: in expansion of macro 'lockdep_assert_held'
  118 |  lockdep_assert_held(&cpu_running);

There are a lot of archs which use cpu_running in smpboot.c (arm,
arm64, openrisc, xtensa, s390, x86, mips), but none of them try
lockdep_assert_held(&cpu_running.wait.lock). So Just remove it.

Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
 arch/riscv/kernel/smpboot.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 4e99227..defc4e1 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -121,7 +121,6 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 
 	ret = start_secondary_cpu(cpu, tidle);
 	if (!ret) {
-		lockdep_assert_held(&cpu_running);
 		wait_for_completion_timeout(&cpu_running,
 					    msecs_to_jiffies(1000));
 
-- 
2.7.4

[PATCH 3/3] riscv: Enable LOCKDEP_SUPPORT & fixup TRACE_IRQFLAGS_SUPPORT

[guoren]

From: Guo Ren <guoren@linux.alibaba.com>

Lockdep is needed by proving the spinlocks and rwlocks. To suupport
it, we need fixup TRACE_IRQFLAGS_SUPPORT in kernel/entry.S. This
patch follow Documentation/irqflags-tracing.txt.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
 arch/riscv/Kconfig        |  3 +++
 arch/riscv/kernel/entry.S | 41 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a31e1a4..550e0ec 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -170,6 +170,9 @@ config PGTABLE_LEVELS
 	default 3 if 64BIT
 	default 2
 
+config LOCKDEP_SUPPORT
+	def_bool y
+
 source "arch/riscv/Kconfig.socs"
 
 menu "Platform type"
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 56d071b..02c5b8e 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -97,17 +97,25 @@ _save_context:
 	la gp, __global_pointer$
 .option pop
 
-	la ra, ret_from_exception
+#ifdef CONFIG_TRACE_IRQFLAGS
+	call trace_hardirqs_off
+#endif
 	/*
 	 * MSB of cause differentiates between
 	 * interrupts and exceptions
 	 */
 	bge s4, zero, 1f
 
+	la ra, ret_from_exception
+
 	/* Handle interrupts */
 	move a0, sp /* pt_regs */
 	tail do_IRQ
 1:
+#ifdef CONFIG_TRACE_IRQFLAGS
+	call trace_hardirqs_on
+	REG_L s1, PT_STATUS(sp)
+#endif
 	/*
 	 * Exceptions run with interrupts enabled or disabled depending on the
 	 * state of SR_PIE in m/sstatus.
@@ -117,8 +125,23 @@ _save_context:
 	csrs CSR_STATUS, SR_IE
 
 1:
+#ifdef CONFIG_TRACE_IRQFLAGS
+	REG_L a0, PT_A0(sp)
+	REG_L a1, PT_A1(sp)
+	REG_L a2, PT_A2(sp)
+	REG_L a3, PT_A3(sp)
+	REG_L a4, PT_A4(sp)
+	REG_L a5, PT_A5(sp)
+	REG_L a6, PT_A6(sp)
+	REG_L a7, PT_A7(sp)
+#endif
+	la ra, ret_from_exception
 	/* Handle syscalls */
 	li t0, EXC_SYSCALL
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+	REG_L s4, PT_CAUSE(sp)
+#endif
 	beq s4, t0, handle_syscall
 
 	/* Handle other exceptions */
@@ -141,6 +164,9 @@ handle_syscall:
 	 * Advance SEPC to avoid executing the original
 	 * scall instruction on sret
 	 */
+#ifdef CONFIG_TRACE_IRQFLAGS
+	REG_L s2, PT_EPC(sp)
+#endif
 	addi s2, s2, 0x4
 	REG_S s2, PT_EPC(sp)
 	/* Trace syscalls, but only if requested by the user. */
@@ -188,6 +214,9 @@ ret_from_syscall_rejected:
 ret_from_exception:
 	REG_L s0, PT_STATUS(sp)
 	csrc CSR_STATUS, SR_IE
+#ifdef CONFIG_TRACE_IRQFLAGS
+	call trace_hardirqs_off
+#endif
 #ifdef CONFIG_RISCV_M_MODE
 	/* the MPP value is too large to be used as an immediate arg for addi */
 	li t0, SR_MPP
@@ -214,6 +243,16 @@ resume_userspace:
 	csrw CSR_SCRATCH, tp
 
 restore_all:
+#ifdef CONFIG_TRACE_IRQFLAGS
+	REG_L s1, PT_STATUS(sp)
+	andi t0, s1, SR_PIE
+	beqz t0, 1f
+	call trace_hardirqs_on
+	j 2f
+1:
+	call trace_hardirqs_off
+2:
+#endif
 	REG_L a0, PT_STATUS(sp)
 	/*
 	 * The current load reservation is effectively part of the processor's
-- 
2.7.4