Re: [PATCH -next V16 4/7] riscv: entry: Convert to generic entry

Conor Dooley
2023-02-05T14:05:05Z

On 5 February 2023 14:56:01 GMT+01:00, Guo Ren <guoren@kernel.org> wrote:
>On Sun, Feb 5, 2023 at 6:43 PM Conor Dooley <conor@kernel.org> wrote:
>>
>> Hey Guo Ren,
>>
>> On 4 February 2023 08:02:10 GMT+01:00, guoren@kernel.org wrote:
>> >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:
>> >
>> > - More clear entry.S with handle_exception and ret_from_exception
>> > - Get rid of complex custom signal implementation
>> > - Move syscall procedure from assembly to C, which is much more
>> > readable.
>> > - Connect ret_from_fork & ret_from_kernel_thread to generic entry.
>> > - Wrap with irqentry_enter/exit and syscall_enter/exit_from_user_mode
>> > - Use the standard preemption code instead of custom
>> >
>> >Suggested-by: Huacai Chen <chenhuacai@kernel.org>
>> >Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
>> >Tested-by: Yipeng Zou <zouyipeng@huawei.com>
>> >Tested-by: Jisheng Zhang <jszhang@kernel.org>
>> >Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
>> >Signed-off-by: Guo Ren <guoren@kernel.org>
>> >Cc: Ben Hutchings <ben@decadent.org.uk>
>> >---
>>
>> Got some new errors added by this patch:
>> https://gist.github.com/conor-pwbot/3b300050a7a4a197bca809935584d809
>>
>> Unfortunately I'm away from a computer at FOSDEM, so I haven't done any investigation
>> of the warnings.
>> Should be reproduceable with gcc-12 allmodconfig.
>Thx for report, but:
>The spin_shadow_stack is from '7e1864332fbc ("riscv: fix race when
>vmap stack overflow")'. Not this patch.
>
>New errors added:
>--- /tmp/tmp.nyMxgc6CGx 2023-02-05 05:12:59.949595120 +0000
>+++ /tmp/tmp.5td5fIdaHX 2023-02-05 05:12:59.961595119 +0000
>@@ -10 +10 @@
>- 1 ../arch/riscv/kernel/traps.c:231:15: warning: symbol
>'spin_shadow_stack' was not declared. Should it be static?
>+ 1 ../arch/riscv/kernel/traps.c:335:15: warning: symbol
>'spin_shadow_stack' was not declared. Should it be static?
>@@ -9109 +9109 @@
>- 37 ../include/linux/fortify-string.h:522:25: warning: call to
>'__read_overflow2_field' declared with attribute warning: detected
>read beyond size of field (2nd parameter); maybe use struct_group()?
>[-Wattribute-warning]
>+ 38 ../include/linux/fortify-string.h:522:25: warning: call to
>'__read_overflow2_field' declared with attribute warning: detected
>read beyond size of field (2nd parameter); maybe use struct_group()?
>[-Wattribute-warning]
>Per-file breakdown
>--- /tmp/tmp.bHiHUVMzmZ 2023-02-05 05:13:00.109595117 +0000
>+++ /tmp/tmp.kUkOd6TrGj 2023-02-05 05:13:00.257595114 +0000
>@@ -1197 +1197 @@
>- 65 ../include/linux/fortify-string.h
>+ 66 ../include/linux/fortify-string.h
>
>Seems the line number change would cause your script to report old
>errors as new. So it would be best to improve the check script, such
>as ignoring the first column line number :)

I thought it already did!
I might've messed up in a refactoring of the script.
I'll fix it up when I get home so, sorry for the noise!

>
>>
>> Thanks,
>> Conor.
>>
>>
>> > arch/riscv/Kconfig | 1 +
>> > arch/riscv/include/asm/asm-prototypes.h | 2 +
>> > arch/riscv/include/asm/csr.h | 1 -
>> > arch/riscv/include/asm/entry-common.h | 11 ++
>> > arch/riscv/include/asm/ptrace.h | 10 +-
>> > arch/riscv/include/asm/stacktrace.h | 5 +
>> > arch/riscv/include/asm/syscall.h | 21 ++
>> > arch/riscv/include/asm/thread_info.h | 13 +-
>> > arch/riscv/kernel/entry.S | 242 ++++--------------------
>> > arch/riscv/kernel/head.h | 1 -
>> > arch/riscv/kernel/ptrace.c | 43 -----
>> > arch/riscv/kernel/signal.c | 29 +--
>> > arch/riscv/kernel/traps.c | 140 ++++++++++++--
>> > arch/riscv/mm/fault.c | 6 +-
>> > 14 files changed, 210 insertions(+), 315 deletions(-)
>> > create mode 100644 arch/riscv/include/asm/entry-common.h
>> >
>> >diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> >index 7c814fbf9527..cbac7b4e3e06 100644
>> >--- a/arch/riscv/Kconfig
>> >+++ b/arch/riscv/Kconfig
>> >@@ -58,6 +58,7 @@ 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/asm-prototypes.h b/arch/riscv/include/asm/asm-prototypes.h
>> >index ef386fcf3939..61ba8ed43d8f 100644
>> >--- a/arch/riscv/include/asm/asm-prototypes.h
>> >+++ b/arch/riscv/include/asm/asm-prototypes.h
>> >@@ -27,5 +27,7 @@ DECLARE_DO_ERROR_INFO(do_trap_break);
>> >
>> > asmlinkage unsigned long get_overflow_stack(void);
>> > asmlinkage void handle_bad_stack(struct pt_regs *regs);
>> >+asmlinkage void do_page_fault(struct pt_regs *regs);
>> >+asmlinkage void do_irq(struct pt_regs *regs);
>> >
>> > #endif /* _ASM_RISCV_PROTOTYPES_H */
>> >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..6e4dee49d84b
>> >--- /dev/null
>> >+++ b/arch/riscv/include/asm/entry-common.h
>> >@@ -0,0 +1,11 @@
>> >+/* SPDX-License-Identifier: GPL-2.0 */
>> >+
>> >+#ifndef _ASM_RISCV_ENTRY_COMMON_H
>> >+#define _ASM_RISCV_ENTRY_COMMON_H
>> >+
>> >+#include <asm/stacktrace.h>
>> >+
>> >+void handle_page_fault(struct pt_regs *regs);
>> >+void handle_break(struct pt_regs *regs);
>> >+
>> >+#endif /* _ASM_RISCV_ENTRY_COMMON_H */
>> >diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
>> >index 6ecd461129d2..b5b0adcc85c1 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_PIE);
>> >+}
>> >+
>> > #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..736110e1fd78 100644
>> >--- a/arch/riscv/include/asm/syscall.h
>> >+++ b/arch/riscv/include/asm/syscall.h
>> >@@ -74,5 +74,26 @@ static inline int syscall_get_arch(struct task_struct *task)
>> > #endif
>> > }
>> >
>> >+typedef long (*syscall_t)(ulong, ulong, ulong, ulong, ulong, ulong, ulong);
>> >+static inline void syscall_handler(struct pt_regs *regs, ulong syscall)
>> >+{
>> >+ syscall_t fn;
>> >+
>> >+#ifdef CONFIG_COMPAT
>> >+ if ((regs->status & SR_UXL) == SR_UXL_32)
>> >+ fn = compat_sys_call_table[syscall];
>> >+ else
>> >+#endif
>> >+ fn = sys_call_table[syscall];
>> >+
>> >+ regs->a0 = fn(regs->orig_a0, regs->a1, regs->a2,
>> >+ regs->a3, regs->a4, regs->a5, regs->a6);
>> >+}
>> >+
>> >+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);
>> > #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 99d38fdf8b18..bc322f92ba34 100644
>> >--- a/arch/riscv/kernel/entry.S
>> >+++ b/arch/riscv/kernel/entry.S
>> >@@ -14,11 +14,7 @@
>> > #include <asm/asm-offsets.h>
>> > #include <asm/errata_list.h>
>> >
>> >-#if !IS_ENABLED(CONFIG_PREEMPTION)
>> >-.set resume_kernel, restore_all
>> >-#endif
>> >-
>> >-ENTRY(handle_exception)
>> >+SYM_CODE_START(handle_exception)
>> > /*
>> > * If coming from userspace, preserve the user thread pointer and load
>> > * the kernel thread pointer. If we came from the kernel, the scratch
>> >@@ -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
>> >@@ -126,38 +111,13 @@ 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
>> >-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
>> >-
>> >+ tail do_irq
>> > 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
>> >@@ -165,95 +125,17 @@ skip_context_tracking:
>> > jr t0
>> > 1:
>> > tail do_trap_unknown
>> >+SYM_CODE_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
>> >- 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
>> >-
>> >+/*
>> >+ * The ret_from_exception must be called with interrupt disabled. Here is the
>> >+ * caller list:
>> >+ * - handle_exception
>> >+ * - ret_from_fork
>> >+ * - ret_from_kernel_thread
>> >+ */
>> > SYM_CODE_START_NOALIGN(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 +143,7 @@ SYM_CODE_START_NOALIGN(ret_from_exception)
>> > #else
>> > andi s0, s0, SR_SPP
>> > #endif
>> >- bnez s0, resume_kernel
>> >-SYM_CODE_END(ret_from_exception)
>> >-
>> >- /* 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, resume_userspace_slow
>> >-resume_userspace:
>> >-#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
>> >@@ -282,18 +154,7 @@ 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
>> >@@ -356,47 +217,10 @@ 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
>> >-
>> >-resume_userspace_slow:
>> >- /* Enter slow path for supplementary processing */
>> >- move a0, sp /* pt_regs */
>> >- move a1, s0 /* current_thread_info->flags */
>> >- call do_work_pending
>> >- j resume_userspace
>> >-
>> >-/* 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
>> >+SYM_CODE_END(ret_from_exception)
>> >
>> > #ifdef CONFIG_VMAP_STACK
>> >-handle_kernel_stack_overflow:
>> >+SYM_CODE_START_LOCAL(handle_kernel_stack_overflow)
>> > /*
>> > * Takes the psuedo-spinlock for the shadow stack, in case multiple
>> > * harts are concurrently overflowing their kernel stacks. We could
>> >@@ -505,23 +329,25 @@ restore_caller_reg:
>> > REG_S s5, PT_TP(sp)
>> > move a0, sp
>> > tail handle_bad_stack
>> >+SYM_CODE_END(handle_kernel_stack_overflow)
>> > #endif
>> >
>> >-END(handle_exception)
>> >-
>> >-ENTRY(ret_from_fork)
>> >+SYM_CODE_START(ret_from_fork)
>> >+ call schedule_tail
>> >+ move a0, sp /* pt_regs */
>> > la ra, ret_from_exception
>> >- tail schedule_tail
>> >-ENDPROC(ret_from_fork)
>> >+ tail syscall_exit_to_user_mode
>> >+SYM_CODE_END(ret_from_fork)
>> >
>> >-ENTRY(ret_from_kernel_thread)
>> >+SYM_CODE_START(ret_from_kernel_thread)
>> > call schedule_tail
>> > /* Call fn(arg) */
>> >- la ra, ret_from_exception
>> > move a0, s1
>> >- jr s0
>> >-ENDPROC(ret_from_kernel_thread)
>> >-
>> >+ jalr s0
>> >+ move a0, sp /* pt_regs */
>> >+ la ra, ret_from_exception
>> >+ tail syscall_exit_to_user_mode
>> >+SYM_CODE_END(ret_from_kernel_thread)
>> >
>> > /*
>> > * Integer register context switch
>> >@@ -533,7 +359,7 @@ ENDPROC(ret_from_kernel_thread)
>> > * The value of a0 and a1 must be preserved by this function, as that's how
>> > * arguments are passed to schedule_tail.
>> > */
>> >-ENTRY(__switch_to)
>> >+SYM_FUNC_START(__switch_to)
>> > /* Save context into prev->thread */
>> > li a4, TASK_THREAD_RA
>> > add a3, a0, a4
>> >@@ -570,7 +396,7 @@ ENTRY(__switch_to)
>> > /* The offset of thread_info in task_struct is zero. */
>> > move tp, a1
>> > ret
>> >-ENDPROC(__switch_to)
>> >+SYM_FUNC_END(__switch_to)
>> >
>> > #ifndef CONFIG_MMU
>> > #define do_page_fault do_trap_unknown
>> >@@ -579,7 +405,7 @@ ENDPROC(__switch_to)
>> > .section ".rodata"
>> > .align LGREG
>> > /* Exception vector table */
>> >-ENTRY(excp_vect_table)
>> >+SYM_CODE_START(excp_vect_table)
>> > RISCV_PTR do_trap_insn_misaligned
>> > ALT_INSN_FAULT(RISCV_PTR do_trap_insn_fault)
>> > RISCV_PTR do_trap_insn_illegal
>> >@@ -588,7 +414,7 @@ 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_trap_ecall_u /* system call */
>> > RISCV_PTR do_trap_ecall_s
>> > RISCV_PTR do_trap_unknown
>> > RISCV_PTR do_trap_ecall_m
>> >@@ -598,11 +424,11 @@ ENTRY(excp_vect_table)
>> > RISCV_PTR do_trap_unknown
>> > RISCV_PTR do_page_fault /* store page fault */
>> > excp_vect_table_end:
>> >-END(excp_vect_table)
>> >+SYM_CODE_END(excp_vect_table)
>> >
>> > #ifndef CONFIG_MMU
>> >-ENTRY(__user_rt_sigreturn)
>> >+SYM_CODE_START(__user_rt_sigreturn)
>> > li a7, __NR_rt_sigreturn
>> > scall
>> >-END(__user_rt_sigreturn)
>> >+SYM_CODE_END(__user_rt_sigreturn)
>> > #endif
>> >diff --git a/arch/riscv/kernel/head.h b/arch/riscv/kernel/head.h
>> >index 726731ada534..a556fdaafed9 100644
>> >--- a/arch/riscv/kernel/head.h
>> >+++ b/arch/riscv/kernel/head.h
>> >@@ -10,7 +10,6 @@
>> >
>> > extern atomic_t hart_lottery;
>> >
>> >-asmlinkage void do_page_fault(struct pt_regs *regs);
>> > asmlinkage void __init setup_vm(uintptr_t dtb_pa);
>> > #ifdef CONFIG_XIP_KERNEL
>> > asmlinkage void __init __copy_data(void);
>> >diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c
>> >index 44f4b1ca315d..23c48b14a0e7 100644
>> >--- a/arch/riscv/kernel/ptrace.c
>> >+++ b/arch/riscv/kernel/ptrace.c
>> >@@ -19,9 +19,6 @@
>> > #include <linux/sched.h>
>> > #include <linux/sched/task_stack.h>
>> >
>> >-#define CREATE_TRACE_POINTS
>> >-#include <trace/events/syscalls.h>
>> >-
>> > enum riscv_regset {
>> > REGSET_X,
>> > #ifdef CONFIG_FPU
>> >@@ -228,46 +225,6 @@ 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 bfb2afa4135f..2e365084417e 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>
>> >@@ -274,7 +275,7 @@ 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;
>> >
>> >@@ -311,29 +312,3 @@ static void do_signal(struct pt_regs *regs)
>> > */
>> > restore_saved_sigmask();
>> > }
>> >-
>> >-/*
>> >- * Handle any pending work on the resume-to-userspace path, as indicated by
>> >- * _TIF_WORK_MASK. Entered from assembly with IRQs off.
>> >- */
>> >-asmlinkage __visible void do_work_pending(struct pt_regs *regs,
>> >- unsigned long thread_info_flags)
>> >-{
>> >- do {
>> >- if (thread_info_flags & _TIF_NEED_RESCHED) {
>> >- schedule();
>> >- } else {
>> >- local_irq_enable();
>> >- 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);
>> >- }
>> >- local_irq_disable();
>> >- thread_info_flags = read_thread_flags();
>> >- } while (thread_info_flags & _TIF_WORK_MASK);
>> >-}
>> >diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
>> >index 96ec76c54ff2..69d619ddbcd5 100644
>> >--- a/arch/riscv/kernel/traps.c
>> >+++ b/arch/riscv/kernel/traps.c
>> >@@ -17,12 +17,14 @@
>> > #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>
>> > #include <asm/csr.h>
>> > #include <asm/processor.h>
>> > #include <asm/ptrace.h>
>> >+#include <asm/syscall.h>
>> > #include <asm/thread_info.h>
>> >
>> > int show_unhandled_signals = 1;
>> >@@ -99,10 +101,18 @@ static void do_trap_error(struct pt_regs *regs, int signo, int code,
>> > #else
>> > #define __trap_section noinstr
>> > #endif
>> >-#define DO_ERROR_INFO(name, signo, code, str) \
>> >-asmlinkage __visible __trap_section void name(struct pt_regs *regs) \
>> >-{ \
>> >- do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \
>> >+#define DO_ERROR_INFO(name, signo, code, str) \
>> >+asmlinkage __visible __trap_section void name(struct pt_regs *regs) \
>> >+{ \
>> >+ if (user_mode(regs)) { \
>> >+ irqentry_enter_from_user_mode(regs); \
>> >+ do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \
>> >+ irqentry_exit_to_user_mode(regs); \
>> >+ } else { \
>> >+ irqentry_state_t state = irqentry_nmi_enter(regs); \
>> >+ do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \
>> >+ irqentry_nmi_exit(regs, state); \
>> >+ } \
>> > }
>> >
>> > DO_ERROR_INFO(do_trap_unknown,
>> >@@ -124,26 +134,50 @@ DO_ERROR_INFO(do_trap_store_misaligned,
>> > int handle_misaligned_load(struct pt_regs *regs);
>> > int handle_misaligned_store(struct pt_regs *regs);
>> >
>> >-asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs)
>> >+asmlinkage __visible __trap_section void do_trap_load_misaligned(struct pt_regs *regs)
>> > {
>> >- if (!handle_misaligned_load(regs))
>> >- return;
>> >- do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
>> >- "Oops - load address misaligned");
>> >+ if (user_mode(regs)) {
>> >+ irqentry_enter_from_user_mode(regs);
>> >+
>> >+ if (handle_misaligned_load(regs))
>> >+ do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
>> >+ "Oops - load address misaligned");
>> >+
>> >+ irqentry_exit_to_user_mode(regs);
>> >+ } else {
>> >+ irqentry_state_t state = irqentry_nmi_enter(regs);
>> >+
>> >+ if (handle_misaligned_load(regs))
>> >+ do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
>> >+ "Oops - load address misaligned");
>> >+
>> >+ irqentry_nmi_exit(regs, state);
>> >+ }
>> > }
>> >
>> >-asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs)
>> >+asmlinkage __visible __trap_section void do_trap_store_misaligned(struct pt_regs *regs)
>> > {
>> >- if (!handle_misaligned_store(regs))
>> >- return;
>> >- do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
>> >- "Oops - store (or AMO) address misaligned");
>> >+ if (user_mode(regs)) {
>> >+ irqentry_enter_from_user_mode(regs);
>> >+
>> >+ if (handle_misaligned_store(regs))
>> >+
>
>
>