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parisc: Avoid using hardware single-step in kprobes 

This patch changes the kprobe and kretprobe feature to use another
break instruction instead of relying on the hardware single-step
feature.
That way those kprobes now work in qemu as well, because in qemu we
don't emulate yet single-stepping.

Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Helge Deller 2021-11-09 22:25:02 +01:00
parent 46162ac2a6
commit 9b046d0245
3 changed files with 24 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/parisc/include/asm/kprobes.h
View File

@ -18,8 +18,9 @@
#include <linux/notifier.h>
#define PARISC_KPROBES_BREAK_INSN 0x3ff801f
#define PARISC_KPROBES_BREAK_INSN2 0x3ff801e
#define __ARCH_WANT_KPROBES_INSN_SLOT
#define MAX_INSN_SIZE 1
#define MAX_INSN_SIZE 2
typedef u32 kprobe_opcode_t;
struct kprobe;
@ -29,7 +30,7 @@ void arch_remove_kprobe(struct kprobe *p);
#define flush_insn_slot(p) \
flush_icache_range((unsigned long)&(p)->ainsn.insn[0], \
(unsigned long)&(p)->ainsn.insn[0] + \
sizeof(kprobe_opcode_t))
MAX_INSN_SIZE*sizeof(kprobe_opcode_t))
#define kretprobe_blacklist_size 0

28
arch/parisc/kernel/kprobes.c
View File

@ -5,6 +5,7 @@
* PA-RISC kprobes implementation
*
* Copyright (c) 2019 Sven Schnelle <svens@stackframe.org>
* Copyright (c) 2022 Helge Deller <deller@gmx.de>
*/
#include <linux/types.h>
@ -25,9 +26,14 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
if (!p->ainsn.insn)
return -ENOMEM;
memcpy(p->ainsn.insn, p->addr,
MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
/*
* Set up new instructions. Second break instruction will
* trigger call of parisc_kprobe_ss_handler().
*/
p->opcode = *p->addr;
p->ainsn.insn[0] = p->opcode;
p->ainsn.insn[1] = PARISC_KPROBES_BREAK_INSN2;
flush_insn_slot(p);
return 0;
}
@ -73,9 +79,7 @@ static void __kprobes setup_singlestep(struct kprobe *p,
{
kcb->iaoq[0] = regs->iaoq[0];
kcb->iaoq[1] = regs->iaoq[1];
regs->iaoq[0] = (unsigned long)p->ainsn.insn;
mtctl(0, 0);
regs->gr[0] |= PSW_R;
instruction_pointer_set(regs, (unsigned long)p->ainsn.insn);
}
int __kprobes parisc_kprobe_break_handler(struct pt_regs *regs)
@ -165,9 +169,8 @@ int __kprobes parisc_kprobe_ss_handler(struct pt_regs *regs)
regs->iaoq[0] = kcb->iaoq[1];
break;
default:
regs->iaoq[1] = kcb->iaoq[0];
regs->iaoq[1] += (regs->iaoq[1] - regs->iaoq[0]) + 4;
regs->iaoq[0] = kcb->iaoq[1];
regs->iaoq[1] = regs->iaoq[0] + 4;
break;
}
kcb->kprobe_status = KPROBE_HIT_SSDONE;
@ -191,14 +194,17 @@ static struct kprobe trampoline_p = {
static int __kprobes trampoline_probe_handler(struct kprobe *p,
struct pt_regs *regs)
{
unsigned long orig_ret_address;
orig_ret_address = __kretprobe_trampoline_handler(regs, NULL);
instruction_pointer_set(regs, orig_ret_address);
__kretprobe_trampoline_handler(regs, NULL);
return 1;
}
void arch_kretprobe_fixup_return(struct pt_regs *regs,
kprobe_opcode_t *correct_ret_addr)
{
regs->gr[2] = (unsigned long)correct_ret_addr;
}
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{

10
arch/parisc/kernel/traps.c
View File

@ -302,7 +302,10 @@ static void handle_break(struct pt_regs *regs)
parisc_kprobe_break_handler(regs);
return;
}
if (unlikely(iir == PARISC_KPROBES_BREAK_INSN2)) {
parisc_kprobe_ss_handler(regs);
return;
}
#endif
#ifdef CONFIG_KGDB
@ -539,11 +542,6 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
/* Recovery counter trap */
regs->gr[0] &= ~PSW_R;
#ifdef CONFIG_KPROBES
if (parisc_kprobe_ss_handler(regs))
return;
#endif
#ifdef CONFIG_KGDB
if (kgdb_single_step) {
kgdb_handle_exception(0, SIGTRAP, 0, regs);