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riscv: kprobes: Remove redundant kprobe_step_ctx 

Inspired by commit ba090f9caf ("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>
This commit is contained in:
Jisheng Zhang 2021-04-19 00:29:19 +08:00 committed by Palmer Dabbelt
parent 37a7a2a10e
commit 8c9f4940c2
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
2 changed files with 9 additions and 38 deletions
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7
arch/riscv/include/asm/kprobes.h
View File

@ -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);

40
arch/riscv/kernel/probes/kprobes.c
View File

@ -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;
}