diff mbox series

[V3,4/7] riscv: convert to generic entry

Message ID 20220906035423.634617-5-guoren@kernel.org (mailing list archive)
State Superseded
Headers show
Series riscv: Add GENERIC_ENTRY, irq stack support | expand

Commit Message

Guo Ren Sept. 6, 2022, 3:54 a.m. UTC
From: Guo Ren <guoren@linux.alibaba.com>

This patch converts riscv to use the generic entry infrastructure from
kernel/entry/*. The generic entry makes maintainers' work easier and
codes more elegant. Here are the changes than before:

 - More clear entry.S with handle_exception and ret_from_exception
 - Get rid of complex custom signal implementation
 - More readable syscall procedure
 - Little modification on ret_from_fork & ret_from_kernel_thread
 - Wrap with irqentry_enter/exit and syscall_enter/exit_from_user_mode
 - Use the standard preemption code instead of custom

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Suggested-by: Huacai Chen <chenhuacai@kernel.org>
---
 arch/riscv/Kconfig                    |   1 +
 arch/riscv/include/asm/csr.h          |   1 -
 arch/riscv/include/asm/entry-common.h |   8 +
 arch/riscv/include/asm/ptrace.h       |  10 +-
 arch/riscv/include/asm/stacktrace.h   |   5 +
 arch/riscv/include/asm/syscall.h      |   6 +
 arch/riscv/include/asm/thread_info.h  |  13 +-
 arch/riscv/kernel/entry.S             | 228 +++-----------------------
 arch/riscv/kernel/irq.c               |  15 ++
 arch/riscv/kernel/ptrace.c            |  40 -----
 arch/riscv/kernel/signal.c            |  21 +--
 arch/riscv/kernel/sys_riscv.c         |  27 +++
 arch/riscv/kernel/traps.c             |  11 ++
 arch/riscv/mm/fault.c                 |  12 +-
 14 files changed, 117 insertions(+), 281 deletions(-)
 create mode 100644 arch/riscv/include/asm/entry-common.h

Comments

Peter Zijlstra Sept. 6, 2022, 9:20 a.m. UTC | #1
On Mon, Sep 05, 2022 at 11:54:20PM -0400, guoren@kernel.org wrote:

> +asmlinkage void noinstr do_riscv_irq(struct pt_regs *regs)
> +{
> +	struct pt_regs *old_regs;
> +	irqentry_state_t state = irqentry_enter(regs);
> +
> +	irq_enter_rcu();
> +	old_regs = set_irq_regs(regs);
> +	handle_arch_irq(regs);
> +	set_irq_regs(old_regs);
> +	irq_exit_rcu();
> +
> +	irqentry_exit(regs, state);
> +}

The above is right in that everything that calls irqentry_enter() should
be noinstr; however all the below instances get it wrong:

>  #define DO_ERROR_INFO(name, signo, code, str)				\
>  asmlinkage __visible __trap_section void name(struct pt_regs *regs)	\
>  {									\
> +	irqentry_state_t state = irqentry_enter(regs);			\
>  	do_trap_error(regs, signo, code, regs->epc, "Oops - " str);	\
> +	irqentry_exit(regs, state);					\
>  }
>  
>  DO_ERROR_INFO(do_trap_unknown,
> @@ -123,18 +126,22 @@ int handle_misaligned_store(struct pt_regs *regs);
>  
>  asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs)
>  {
> +	irqentry_state_t state = irqentry_enter(regs);
>  	if (!handle_misaligned_load(regs))
>  		return;
>  	do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
>  		      "Oops - load address misaligned");
> +	irqentry_exit(regs, state);
>  }
>  
>  asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs)
>  {
> +	irqentry_state_t state = irqentry_enter(regs);
>  	if (!handle_misaligned_store(regs))
>  		return;
>  	do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
>  		      "Oops - store (or AMO) address misaligned");
> +	irqentry_exit(regs, state);
>  }
>  #endif
>  DO_ERROR_INFO(do_trap_store_fault,
> @@ -158,6 +165,8 @@ static inline unsigned long get_break_insn_length(unsigned long pc)
>  
>  asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
>  {
> +	irqentry_state_t state = irqentry_enter(regs);
> +
>  #ifdef CONFIG_KPROBES
>  	if (kprobe_single_step_handler(regs))
>  		return;
> @@ -185,6 +194,8 @@ asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
>  		regs->epc += get_break_insn_length(regs->epc);
>  	else
>  		die(regs, "Kernel BUG");
> +
> +	irqentry_exit(regs, state);
>  }
>  NOKPROBE_SYMBOL(do_trap_break);

> +asmlinkage void do_page_fault(struct pt_regs *regs)
> +{
> +	irqentry_state_t state = irqentry_enter(regs);
> +
> +	__do_page_fault(regs);
> +
> +	irqentry_exit(regs, state);
> +}
>  NOKPROBE_SYMBOL(do_page_fault);

Without noinstr the compiler is free to insert instrumentation (think
all the k*SAN, KCov, GCov, ftrace etc..) which can call code we're not
yet ready to run this early in the entry path, for instance it could
rely on RCU which isn't on yet, or expect lockdep state.
Guo Ren Sept. 7, 2022, 12:59 a.m. UTC | #2
On Tue, Sep 6, 2022 at 5:20 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Mon, Sep 05, 2022 at 11:54:20PM -0400, guoren@kernel.org wrote:
>
> > +asmlinkage void noinstr do_riscv_irq(struct pt_regs *regs)
> > +{
> > +     struct pt_regs *old_regs;
> > +     irqentry_state_t state = irqentry_enter(regs);
> > +
> > +     irq_enter_rcu();
> > +     old_regs = set_irq_regs(regs);
> > +     handle_arch_irq(regs);
> > +     set_irq_regs(old_regs);
> > +     irq_exit_rcu();
> > +
> > +     irqentry_exit(regs, state);
> > +}
>
> The above is right in that everything that calls irqentry_enter() should
> be noinstr; however all the below instances get it wrong:
>
> >  #define DO_ERROR_INFO(name, signo, code, str)                                \
> >  asmlinkage __visible __trap_section void name(struct pt_regs *regs)  \
> >  {                                                                    \
> > +     irqentry_state_t state = irqentry_enter(regs);                  \
> >       do_trap_error(regs, signo, code, regs->epc, "Oops - " str);     \
> > +     irqentry_exit(regs, state);                                     \
> >  }
> >
> >  DO_ERROR_INFO(do_trap_unknown,
> > @@ -123,18 +126,22 @@ int handle_misaligned_store(struct pt_regs *regs);
> >
> >  asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs)
> >  {
> > +     irqentry_state_t state = irqentry_enter(regs);
> >       if (!handle_misaligned_load(regs))
> >               return;
> >       do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
> >                     "Oops - load address misaligned");
> > +     irqentry_exit(regs, state);
> >  }
> >
> >  asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs)
> >  {
> > +     irqentry_state_t state = irqentry_enter(regs);
> >       if (!handle_misaligned_store(regs))
> >               return;
> >       do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
> >                     "Oops - store (or AMO) address misaligned");
> > +     irqentry_exit(regs, state);
> >  }
> >  #endif
> >  DO_ERROR_INFO(do_trap_store_fault,
> > @@ -158,6 +165,8 @@ static inline unsigned long get_break_insn_length(unsigned long pc)
> >
> >  asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
> >  {
> > +     irqentry_state_t state = irqentry_enter(regs);
> > +
> >  #ifdef CONFIG_KPROBES
> >       if (kprobe_single_step_handler(regs))
> >               return;
> > @@ -185,6 +194,8 @@ asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
> >               regs->epc += get_break_insn_length(regs->epc);
> >       else
> >               die(regs, "Kernel BUG");
> > +
> > +     irqentry_exit(regs, state);
> >  }
> >  NOKPROBE_SYMBOL(do_trap_break);
>
> > +asmlinkage void do_page_fault(struct pt_regs *regs)
> > +{
> > +     irqentry_state_t state = irqentry_enter(regs);
> > +
> > +     __do_page_fault(regs);
> > +
> > +     irqentry_exit(regs, state);
> > +}
> >  NOKPROBE_SYMBOL(do_page_fault);
>
> Without noinstr the compiler is free to insert instrumentation (think
> all the k*SAN, KCov, GCov, ftrace etc..) which can call code we're not
> yet ready to run this early in the entry path, for instance it could
> rely on RCU which isn't on yet, or expect lockdep state.
I'll add a patch to fix it in the next version. Thx for pointing it out.

>
>
diff mbox series

Patch

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index ed66c31e4655..a07bb3b73b5b 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -56,6 +56,7 @@  config RISCV
 	select GENERIC_ATOMIC64 if !64BIT
 	select GENERIC_CLOCKEVENTS_BROADCAST if SMP
 	select GENERIC_EARLY_IOREMAP
+	select GENERIC_ENTRY
 	select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
 	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_IOREMAP if MMU
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 0e571f6483d9..7c2b8cdb7b77 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -40,7 +40,6 @@ 
 #define SR_UXL		_AC(0x300000000, UL) /* XLEN mask for U-mode */
 #define SR_UXL_32	_AC(0x100000000, UL) /* XLEN = 32 for U-mode */
 #define SR_UXL_64	_AC(0x200000000, UL) /* XLEN = 64 for U-mode */
-#define SR_UXL_SHIFT	32
 #endif
 
 /* SATP flags */
diff --git a/arch/riscv/include/asm/entry-common.h b/arch/riscv/include/asm/entry-common.h
new file mode 100644
index 000000000000..1636ac2af28e
--- /dev/null
+++ b/arch/riscv/include/asm/entry-common.h
@@ -0,0 +1,8 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_RISCV_ENTRY_COMMON_H
+#define _ASM_RISCV_ENTRY_COMMON_H
+
+#include <asm/stacktrace.h>
+
+#endif /* _ASM_RISCV_ENTRY_COMMON_H */
diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
index 6ecd461129d2..4e46a611f255 100644
--- a/arch/riscv/include/asm/ptrace.h
+++ b/arch/riscv/include/asm/ptrace.h
@@ -53,6 +53,9 @@  struct pt_regs {
 	unsigned long orig_a0;
 };
 
+#define PTRACE_SYSEMU			0x1f
+#define PTRACE_SYSEMU_SINGLESTEP	0x20
+
 #ifdef CONFIG_64BIT
 #define REG_FMT "%016lx"
 #else
@@ -121,8 +124,6 @@  extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 
 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 			   unsigned long frame_pointer);
-int do_syscall_trace_enter(struct pt_regs *regs);
-void do_syscall_trace_exit(struct pt_regs *regs);
 
 /**
  * regs_get_register() - get register value from its offset
@@ -172,6 +173,11 @@  static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 	return 0;
 }
 
+static inline int regs_irqs_disabled(struct pt_regs *regs)
+{
+	return !(regs->status & SR_IE);
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_RISCV_PTRACE_H */
diff --git a/arch/riscv/include/asm/stacktrace.h b/arch/riscv/include/asm/stacktrace.h
index 3450c1912afd..f7e8ef2418b9 100644
--- a/arch/riscv/include/asm/stacktrace.h
+++ b/arch/riscv/include/asm/stacktrace.h
@@ -16,4 +16,9 @@  extern void notrace walk_stackframe(struct task_struct *task, struct pt_regs *re
 extern void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
 			   const char *loglvl);
 
+static inline bool on_thread_stack(void)
+{
+	return !(((unsigned long)(current->stack) ^ current_stack_pointer) & ~(THREAD_SIZE - 1));
+}
+
 #endif /* _ASM_RISCV_STACKTRACE_H */
diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
index 384a63b86420..6c573f18030b 100644
--- a/arch/riscv/include/asm/syscall.h
+++ b/arch/riscv/include/asm/syscall.h
@@ -74,5 +74,11 @@  static inline int syscall_get_arch(struct task_struct *task)
 #endif
 }
 
+static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
+{
+	return false;
+}
+
 asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t);
+asmlinkage void do_sys_ecall_u(struct pt_regs *regs);
 #endif	/* _ASM_RISCV_SYSCALL_H */
diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h
index 67322f878e0d..7de4fb96f0b5 100644
--- a/arch/riscv/include/asm/thread_info.h
+++ b/arch/riscv/include/asm/thread_info.h
@@ -66,6 +66,7 @@  struct thread_info {
 	long			kernel_sp;	/* Kernel stack pointer */
 	long			user_sp;	/* User stack pointer */
 	int			cpu;
+	unsigned long		syscall_work;	/* SYSCALL_WORK_ flags */
 };
 
 /*
@@ -88,26 +89,18 @@  struct thread_info {
  * - pending work-to-be-done flags are in lowest half-word
  * - other flags in upper half-word(s)
  */
-#define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_RESTORE_SIGMASK	4	/* restore signal mask in do_signal() */
 #define TIF_MEMDIE		5	/* is terminating due to OOM killer */
-#define TIF_SYSCALL_TRACEPOINT  6       /* syscall tracepoint instrumentation */
-#define TIF_SYSCALL_AUDIT	7	/* syscall auditing */
-#define TIF_SECCOMP		8	/* syscall secure computing */
 #define TIF_NOTIFY_SIGNAL	9	/* signal notifications exist */
 #define TIF_UPROBE		10	/* uprobe breakpoint or singlestep */
 #define TIF_32BIT		11	/* compat-mode 32bit process */
 
-#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
-#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
-#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
-#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_UPROBE		(1 << TIF_UPROBE)
 
@@ -115,8 +108,4 @@  struct thread_info {
 	(_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED | \
 	 _TIF_NOTIFY_SIGNAL | _TIF_UPROBE)
 
-#define _TIF_SYSCALL_WORK \
-	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_AUDIT | \
-	 _TIF_SECCOMP)
-
 #endif /* _ASM_RISCV_THREAD_INFO_H */
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index b9eda3fcbd6d..5f49517cd3a2 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -14,10 +14,6 @@ 
 #include <asm/asm-offsets.h>
 #include <asm/errata_list.h>
 
-#if !IS_ENABLED(CONFIG_PREEMPTION)
-.set resume_kernel, restore_all
-#endif
-
 ENTRY(handle_exception)
 	/*
 	 * If coming from userspace, preserve the user thread pointer and load
@@ -106,19 +102,8 @@  _save_context:
 .option norelax
 	la gp, __global_pointer$
 .option pop
-
-#ifdef CONFIG_TRACE_IRQFLAGS
-	call __trace_hardirqs_off
-#endif
-
-#ifdef CONFIG_CONTEXT_TRACKING_USER
-	/* If previous state is in user mode, call user_exit_callable(). */
-	li   a0, SR_PP
-	and a0, s1, a0
-	bnez a0, skip_context_tracking
-	call user_exit_callable
-skip_context_tracking:
-#endif
+	move a0, sp /* pt_regs */
+	la ra, ret_from_exception
 
 	/*
 	 * MSB of cause differentiates between
@@ -126,134 +111,26 @@  skip_context_tracking:
 	 */
 	bge s4, zero, 1f
 
-	la ra, ret_from_exception
-
 	/* Handle interrupts */
-	move a0, sp /* pt_regs */
-	la a1, generic_handle_arch_irq
-	jr a1
+	tail do_riscv_irq
 1:
-	/*
-	 * Exceptions run with interrupts enabled or disabled depending on the
-	 * state of SR_PIE in m/sstatus.
-	 */
-	andi t0, s1, SR_PIE
-	beqz t0, 1f
-	/* kprobes, entered via ebreak, must have interrupts disabled. */
-	li t0, EXC_BREAKPOINT
-	beq s4, t0, 1f
-#ifdef CONFIG_TRACE_IRQFLAGS
-	call __trace_hardirqs_on
-#endif
-	csrs CSR_STATUS, SR_IE
-
-1:
-	la ra, ret_from_exception
-	/* Handle syscalls */
-	li t0, EXC_SYSCALL
-	beq s4, t0, handle_syscall
-
 	/* Handle other exceptions */
 	slli t0, s4, RISCV_LGPTR
 	la t1, excp_vect_table
 	la t2, excp_vect_table_end
-	move a0, sp /* pt_regs */
 	add t0, t1, t0
 	/* Check if exception code lies within bounds */
-	bgeu t0, t2, 1f
+	bgeu t0, t2, 2f
 	REG_L t0, 0(t0)
 	jr t0
-1:
+2:
 	tail do_trap_unknown
+END(handle_exception)
 
-handle_syscall:
-#ifdef CONFIG_RISCV_M_MODE
-	/*
-	 * When running is M-Mode (no MMU config), MPIE does not get set.
-	 * As a result, we need to force enable interrupts here because
-	 * handle_exception did not do set SR_IE as it always sees SR_PIE
-	 * being cleared.
-	 */
-	csrs CSR_STATUS, SR_IE
-#endif
-#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER)
-	/* Recover a0 - a7 for system calls */
-	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
-	 /* save the initial A0 value (needed in signal handlers) */
-	REG_S a0, PT_ORIG_A0(sp)
-	/*
-	 * Advance SEPC to avoid executing the original
-	 * scall instruction on sret
-	 */
-	addi s2, s2, 0x4
-	REG_S s2, PT_EPC(sp)
-	/* Trace syscalls, but only if requested by the user. */
-	REG_L t0, TASK_TI_FLAGS(tp)
-	andi t0, t0, _TIF_SYSCALL_WORK
-	bnez t0, handle_syscall_trace_enter
-check_syscall_nr:
-	/* Check to make sure we don't jump to a bogus syscall number. */
-	li t0, __NR_syscalls
-	la s0, sys_ni_syscall
-	/*
-	 * Syscall number held in a7.
-	 * If syscall number is above allowed value, redirect to ni_syscall.
-	 */
-	bgeu a7, t0, 3f
-#ifdef CONFIG_COMPAT
+ENTRY(ret_from_exception)
 	REG_L s0, PT_STATUS(sp)
-	srli s0, s0, SR_UXL_SHIFT
-	andi s0, s0, (SR_UXL >> SR_UXL_SHIFT)
-	li t0, (SR_UXL_32 >> SR_UXL_SHIFT)
-	sub t0, s0, t0
-	bnez t0, 1f
-
-	/* Call compat_syscall */
-	la s0, compat_sys_call_table
-	j 2f
-1:
-#endif
-	/* Call syscall */
-	la s0, sys_call_table
-2:
-	slli t0, a7, RISCV_LGPTR
-	add s0, s0, t0
-	REG_L s0, 0(s0)
-3:
-	jalr s0
 
-ret_from_syscall:
-	/* Set user a0 to kernel a0 */
-	REG_S a0, PT_A0(sp)
-	/*
-	 * We didn't execute the actual syscall.
-	 * Seccomp already set return value for the current task pt_regs.
-	 * (If it was configured with SECCOMP_RET_ERRNO/TRACE)
-	 */
-ret_from_syscall_rejected:
-#ifdef CONFIG_DEBUG_RSEQ
-	move a0, sp
-	call rseq_syscall
-#endif
-	/* Trace syscalls, but only if requested by the user. */
-	REG_L t0, TASK_TI_FLAGS(tp)
-	andi t0, t0, _TIF_SYSCALL_WORK
-	bnez t0, handle_syscall_trace_exit
-
-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
@@ -261,17 +138,7 @@  ret_from_exception:
 #else
 	andi s0, s0, SR_SPP
 #endif
-	bnez s0, resume_kernel
-
-resume_userspace:
-	/* Interrupts must be disabled here so flags are checked atomically */
-	REG_L s0, TASK_TI_FLAGS(tp) /* current_thread_info->flags */
-	andi s1, s0, _TIF_WORK_MASK
-	bnez s1, work_pending
-
-#ifdef CONFIG_CONTEXT_TRACKING_USER
-	call user_enter_callable
-#endif
+	bnez s0, 1f
 
 	/* Save unwound kernel stack pointer in thread_info */
 	addi s0, sp, PT_SIZE_ON_STACK
@@ -282,19 +149,7 @@  resume_userspace:
 	 * structures again.
 	 */
 	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
 	 * state, in the sense that load reservations cannot be shared between
@@ -315,9 +170,11 @@  restore_all:
 	REG_L  a2, PT_EPC(sp)
 	REG_SC x0, a2, PT_EPC(sp)
 
-	csrw CSR_STATUS, a0
 	csrw CSR_EPC, a2
 
+	REG_L a0, PT_STATUS(sp)
+	csrw CSR_STATUS, a0
+
 	REG_L x1,  PT_RA(sp)
 	REG_L x3,  PT_GP(sp)
 	REG_L x4,  PT_TP(sp)
@@ -356,54 +213,10 @@  restore_all:
 #else
 	sret
 #endif
-
-#if IS_ENABLED(CONFIG_PREEMPTION)
-resume_kernel:
-	REG_L s0, TASK_TI_PREEMPT_COUNT(tp)
-	bnez s0, restore_all
-	REG_L s0, TASK_TI_FLAGS(tp)
-	andi s0, s0, _TIF_NEED_RESCHED
-	beqz s0, restore_all
-	call preempt_schedule_irq
-	j restore_all
-#endif
-
-work_pending:
-	/* Enter slow path for supplementary processing */
-	la ra, ret_from_exception
-	andi s1, s0, _TIF_NEED_RESCHED
-	bnez s1, work_resched
-work_notifysig:
-	/* Handle pending signals and notify-resume requests */
-	csrs CSR_STATUS, SR_IE /* Enable interrupts for do_notify_resume() */
-	move a0, sp /* pt_regs */
-	move a1, s0 /* current_thread_info->flags */
-	tail do_notify_resume
-work_resched:
-	tail schedule
-
-/* Slow paths for ptrace. */
-handle_syscall_trace_enter:
-	move a0, sp
-	call do_syscall_trace_enter
-	move t0, a0
-	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)
-	bnez t0, ret_from_syscall_rejected
-	j check_syscall_nr
-handle_syscall_trace_exit:
-	move a0, sp
-	call do_syscall_trace_exit
-	j ret_from_exception
+END(ret_from_exception)
 
 #ifdef CONFIG_VMAP_STACK
-handle_kernel_stack_overflow:
+ENTRY(handle_kernel_stack_overflow)
 	la sp, shadow_stack
 	addi sp, sp, SHADOW_OVERFLOW_STACK_SIZE
 
@@ -499,21 +312,24 @@  restore_caller_reg:
 	REG_S s5, PT_TP(sp)
 	move a0, sp
 	tail handle_bad_stack
+END(handle_kernel_stack_overflow)
 #endif
 
-END(handle_exception)
-
 ENTRY(ret_from_fork)
+	call schedule_tail
+	move a0, sp /* pt_regs */
 	la ra, ret_from_exception
-	tail schedule_tail
+	tail syscall_exit_to_user_mode
 ENDPROC(ret_from_fork)
 
 ENTRY(ret_from_kernel_thread)
 	call schedule_tail
 	/* Call fn(arg) */
-	la ra, ret_from_exception
 	move a0, s1
-	jr s0
+	jalr s0
+	move a0, sp /* pt_regs */
+	la ra, ret_from_exception
+	tail syscall_exit_to_user_mode
 ENDPROC(ret_from_kernel_thread)
 
 
@@ -582,7 +398,7 @@  ENTRY(excp_vect_table)
 	RISCV_PTR do_trap_load_fault
 	RISCV_PTR do_trap_store_misaligned
 	RISCV_PTR do_trap_store_fault
-	RISCV_PTR do_trap_ecall_u /* system call, gets intercepted */
+	RISCV_PTR do_sys_ecall_u /* system call */
 	RISCV_PTR do_trap_ecall_s
 	RISCV_PTR do_trap_unknown
 	RISCV_PTR do_trap_ecall_m
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index 7207fa08d78f..24c2e1bd756a 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -5,6 +5,7 @@ 
  * Copyright (C) 2018 Christoph Hellwig
  */
 
+#include <linux/entry-common.h>
 #include <linux/interrupt.h>
 #include <linux/irqchip.h>
 #include <linux/seq_file.h>
@@ -22,3 +23,17 @@  void __init init_IRQ(void)
 	if (!handle_arch_irq)
 		panic("No interrupt controller found.");
 }
+
+asmlinkage void noinstr do_riscv_irq(struct pt_regs *regs)
+{
+	struct pt_regs *old_regs;
+	irqentry_state_t state = irqentry_enter(regs);
+
+	irq_enter_rcu();
+	old_regs = set_irq_regs(regs);
+	handle_arch_irq(regs);
+	set_irq_regs(old_regs);
+	irq_exit_rcu();
+
+	irqentry_exit(regs, state);
+}
diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c
index 44f4b1ca315d..4caed6c683e4 100644
--- a/arch/riscv/kernel/ptrace.c
+++ b/arch/riscv/kernel/ptrace.c
@@ -228,46 +228,6 @@  long arch_ptrace(struct task_struct *child, long request,
 	return ret;
 }
 
-/*
- * Allows PTRACE_SYSCALL to work.  These are called from entry.S in
- * {handle,ret_from}_syscall.
- */
-__visible int do_syscall_trace_enter(struct pt_regs *regs)
-{
-	if (test_thread_flag(TIF_SYSCALL_TRACE))
-		if (ptrace_report_syscall_entry(regs))
-			return -1;
-
-	/*
-	 * Do the secure computing after ptrace; failures should be fast.
-	 * If this fails we might have return value in a0 from seccomp
-	 * (via SECCOMP_RET_ERRNO/TRACE).
-	 */
-	if (secure_computing() == -1)
-		return -1;
-
-#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
-	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
-		trace_sys_enter(regs, syscall_get_nr(current, regs));
-#endif
-
-	audit_syscall_entry(regs->a7, regs->a0, regs->a1, regs->a2, regs->a3);
-	return 0;
-}
-
-__visible void do_syscall_trace_exit(struct pt_regs *regs)
-{
-	audit_syscall_exit(regs);
-
-	if (test_thread_flag(TIF_SYSCALL_TRACE))
-		ptrace_report_syscall_exit(regs, 0);
-
-#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
-	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
-		trace_sys_exit(regs, regs_return_value(regs));
-#endif
-}
-
 #ifdef CONFIG_COMPAT
 static int compat_riscv_gpr_get(struct task_struct *target,
 				const struct user_regset *regset,
diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
index 5a2de6b6f882..5871eccbbd94 100644
--- a/arch/riscv/kernel/signal.c
+++ b/arch/riscv/kernel/signal.c
@@ -12,6 +12,7 @@ 
 #include <linux/syscalls.h>
 #include <linux/resume_user_mode.h>
 #include <linux/linkage.h>
+#include <linux/entry-common.h>
 
 #include <asm/ucontext.h>
 #include <asm/vdso.h>
@@ -272,7 +273,7 @@  static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 	signal_setup_done(ret, ksig, 0);
 }
 
-static void do_signal(struct pt_regs *regs)
+void arch_do_signal_or_restart(struct pt_regs *regs)
 {
 	struct ksignal ksig;
 
@@ -309,21 +310,3 @@  static void do_signal(struct pt_regs *regs)
 	 */
 	restore_saved_sigmask();
 }
-
-/*
- * notification of userspace execution resumption
- * - triggered by the _TIF_WORK_MASK flags
- */
-asmlinkage __visible void do_notify_resume(struct pt_regs *regs,
-					   unsigned long thread_info_flags)
-{
-	if (thread_info_flags & _TIF_UPROBE)
-		uprobe_notify_resume(regs);
-
-	/* Handle pending signal delivery */
-	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
-		do_signal(regs);
-
-	if (thread_info_flags & _TIF_NOTIFY_RESUME)
-		resume_user_mode_work(regs);
-}
diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index 571556bb9261..41cc1c4bccb3 100644
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -5,8 +5,10 @@ 
  * Copyright (C) 2017 SiFive
  */
 
+#include <linux/entry-common.h>
 #include <linux/syscalls.h>
 #include <asm/unistd.h>
+#include <asm/syscall.h>
 #include <asm/cacheflush.h>
 #include <asm-generic/mman-common.h>
 
@@ -72,3 +74,28 @@  SYSCALL_DEFINE3(riscv_flush_icache, uintptr_t, start, uintptr_t, end,
 
 	return 0;
 }
+
+typedef long (*syscall_t)(ulong, ulong, ulong, ulong, ulong, ulong, ulong);
+
+asmlinkage void do_sys_ecall_u(struct pt_regs *regs)
+{
+	syscall_t syscall;
+	ulong nr = regs->a7;
+
+	regs->epc += 4;
+	regs->orig_a0 = regs->a0;
+	regs->a0 = -ENOSYS;
+
+	nr = syscall_enter_from_user_mode(regs, nr);
+#ifdef CONFIG_COMPAT
+	if ((regs->status & SR_UXL) == SR_UXL_32)
+		syscall = compat_sys_call_table[nr];
+	else
+#endif
+		syscall = sys_call_table[nr];
+
+	if (nr < NR_syscalls)
+		regs->a0 = syscall(regs->orig_a0, regs->a1, regs->a2,
+				   regs->a3, regs->a4, regs->a5, regs->a6);
+	syscall_exit_to_user_mode(regs);
+}
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 635e6ec26938..751745de10c5 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -17,6 +17,7 @@ 
 #include <linux/module.h>
 #include <linux/irq.h>
 #include <linux/kexec.h>
+#include <linux/entry-common.h>
 
 #include <asm/asm-prototypes.h>
 #include <asm/bug.h>
@@ -99,7 +100,9 @@  static void do_trap_error(struct pt_regs *regs, int signo, int code,
 #define DO_ERROR_INFO(name, signo, code, str)				\
 asmlinkage __visible __trap_section void name(struct pt_regs *regs)	\
 {									\
+	irqentry_state_t state = irqentry_enter(regs);			\
 	do_trap_error(regs, signo, code, regs->epc, "Oops - " str);	\
+	irqentry_exit(regs, state);					\
 }
 
 DO_ERROR_INFO(do_trap_unknown,
@@ -123,18 +126,22 @@  int handle_misaligned_store(struct pt_regs *regs);
 
 asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs)
 {
+	irqentry_state_t state = irqentry_enter(regs);
 	if (!handle_misaligned_load(regs))
 		return;
 	do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
 		      "Oops - load address misaligned");
+	irqentry_exit(regs, state);
 }
 
 asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs)
 {
+	irqentry_state_t state = irqentry_enter(regs);
 	if (!handle_misaligned_store(regs))
 		return;
 	do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
 		      "Oops - store (or AMO) address misaligned");
+	irqentry_exit(regs, state);
 }
 #endif
 DO_ERROR_INFO(do_trap_store_fault,
@@ -158,6 +165,8 @@  static inline unsigned long get_break_insn_length(unsigned long pc)
 
 asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
 {
+	irqentry_state_t state = irqentry_enter(regs);
+
 #ifdef CONFIG_KPROBES
 	if (kprobe_single_step_handler(regs))
 		return;
@@ -185,6 +194,8 @@  asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
 		regs->epc += get_break_insn_length(regs->epc);
 	else
 		die(regs, "Kernel BUG");
+
+	irqentry_exit(regs, state);
 }
 NOKPROBE_SYMBOL(do_trap_break);
 
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index f2fbd1400b7c..45cd200114b1 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -15,6 +15,7 @@ 
 #include <linux/uaccess.h>
 #include <linux/kprobes.h>
 #include <linux/kfence.h>
+#include <linux/entry-common.h>
 
 #include <asm/ptrace.h>
 #include <asm/tlbflush.h>
@@ -203,7 +204,7 @@  static inline bool access_error(unsigned long cause, struct vm_area_struct *vma)
  * This routine handles page faults.  It determines the address and the
  * problem, and then passes it off to one of the appropriate routines.
  */
-asmlinkage void do_page_fault(struct pt_regs *regs)
+static void __do_page_fault(struct pt_regs *regs)
 {
 	struct task_struct *tsk;
 	struct vm_area_struct *vma;
@@ -350,4 +351,13 @@  asmlinkage void do_page_fault(struct pt_regs *regs)
 	}
 	return;
 }
+
+asmlinkage void do_page_fault(struct pt_regs *regs)
+{
+	irqentry_state_t state = irqentry_enter(regs);
+
+	__do_page_fault(regs);
+
+	irqentry_exit(regs, state);
+}
 NOKPROBE_SYMBOL(do_page_fault);