riscv: kprobes: Remove redundant kprobe_step_ctx

Inspired by commit ba090f9cafd5 ("arm64: kprobes: Remove redundant
kprobe_step_ctx"), the ss_pending and match_addr of kprobe_step_ctx
are redundant because those can be replaced by KPROBE_HIT_SS and
&cur_kprobe->ainsn.api.insn[0] + GET_INSN_LENGTH(cur->opcode)
respectively.

Remove the kprobe_step_ctx to simplify the code.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

diff --git a/arch/riscv/include/asm/kprobes.h b/arch/riscv/include/asm/kprobes.h
index 4647d38..9ea9b5e 100644 (file)
--- a/arch/riscv/include/asm/kprobes.h
+++ b/arch/riscv/include/asm/kprobes.h
@@ -29,18 +29,11 @@ struct prev_kprobe {
        unsigned int status;
 };
 
-/* Single step context for kprobe */
-struct kprobe_step_ctx {
-       unsigned long ss_pending;
-       unsigned long match_addr;
-};
-
 /* per-cpu kprobe control block */
 struct kprobe_ctlblk {
        unsigned int kprobe_status;
        unsigned long saved_status;
        struct prev_kprobe prev_kprobe;
-       struct kprobe_step_ctx ss_ctx;
 };
 
 void arch_remove_kprobe(struct kprobe *p);

diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
index 10b965c..fbd127d 100644 (file)
--- a/arch/riscv/kernel/probes/kprobes.c
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -17,7 +17,7 @@ DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
 static void __kprobes
-post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *);
+post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *);
 
 static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
 {
@@ -43,7 +43,7 @@ static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
                p->ainsn.api.handler((u32)p->opcode,
                                        (unsigned long)p->addr, regs);
 
-       post_kprobe_handler(kcb, regs);
+       post_kprobe_handler(p, kcb, regs);
 }
 
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
@@ -149,21 +149,6 @@ static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb,
        regs->status = kcb->saved_status;
 }
 
-static void __kprobes
-set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr, struct kprobe *p)
-{
-       unsigned long offset = GET_INSN_LENGTH(p->opcode);
-
-       kcb->ss_ctx.ss_pending = true;
-       kcb->ss_ctx.match_addr = addr + offset;
-}
-
-static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb)
-{
-       kcb->ss_ctx.ss_pending = false;
-       kcb->ss_ctx.match_addr = 0;
-}
-
 static void __kprobes setup_singlestep(struct kprobe *p,
                                       struct pt_regs *regs,
                                       struct kprobe_ctlblk *kcb, int reenter)
@@ -182,8 +167,6 @@ static void __kprobes setup_singlestep(struct kprobe *p,
                /* prepare for single stepping */
                slot = (unsigned long)p->ainsn.api.insn;
 
-               set_ss_context(kcb, slot, p);   /* mark pending ss */
-
                /* IRQs and single stepping do not mix well. */
                kprobes_save_local_irqflag(kcb, regs);
 
@@ -219,13 +202,8 @@ static int __kprobes reenter_kprobe(struct kprobe *p,
 }
 
 static void __kprobes
-post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs)
+post_kprobe_handler(struct kprobe *cur, struct kprobe_ctlblk *kcb, struct pt_regs *regs)
 {
-       struct kprobe *cur = kprobe_running();
-
-       if (!cur)
-               return;
-
        /* return addr restore if non-branching insn */
        if (cur->ainsn.api.restore != 0)
                regs->epc = cur->ainsn.api.restore;
@@ -357,16 +335,16 @@ bool __kprobes
 kprobe_single_step_handler(struct pt_regs *regs)
 {
        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+       unsigned long addr = instruction_pointer(regs);
+       struct kprobe *cur = kprobe_running();
 
-       if ((kcb->ss_ctx.ss_pending)
-           && (kcb->ss_ctx.match_addr == instruction_pointer(regs))) {
-               clear_ss_context(kcb);  /* clear pending ss */
-
+       if (cur && (kcb->kprobe_status & (KPROBE_HIT_SS | KPROBE_REENTER)) &&
+           ((unsigned long)&cur->ainsn.api.insn[0] + GET_INSN_LENGTH(cur->opcode) == addr)) {
                kprobes_restore_local_irqflag(kcb, regs);
-
-               post_kprobe_handler(kcb, regs);
+               post_kprobe_handler(cur, kcb, regs);
                return true;
        }
+       /* not ours, kprobes should ignore it */
        return false;
 }