[PATCH -tip v6 07/27] powerpc/kprobes: Remove jprobe powerpc implementation

Masami Hiramatsu
2018-06-19T16:08:01Z

Remove arch dependent setjump/longjump functions
and unused fields in kprobe_ctlblk for jprobes
from arch/powerpc. This also reverts commits
related __is_active_jprobe() function.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
---
arch/powerpc/include/asm/kprobes.h | 2 -
arch/powerpc/kernel/kprobes-ftrace.c | 15 -------
arch/powerpc/kernel/kprobes.c | 54 ------------------------
arch/powerpc/kernel/trace/ftrace_64_mprofile.S | 39 ++---------------
4 files changed, 5 insertions(+), 105 deletions(-)

diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h
index 9f3be5c8a4a3..674036db558b 100644
--- a/arch/powerpc/include/asm/kprobes.h
+++ b/arch/powerpc/include/asm/kprobes.h
@@ -88,7 +88,6 @@ struct prev_kprobe {
struct kprobe_ctlblk {
unsigned long kprobe_status;
unsigned long kprobe_saved_msr;
- struct pt_regs jprobe_saved_regs;
struct prev_kprobe prev_kprobe;
};

@@ -104,7 +103,6 @@ extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
extern int kprobe_handler(struct pt_regs *regs);
extern int kprobe_post_handler(struct pt_regs *regs);
#ifdef CONFIG_KPROBES_ON_FTRACE
-extern int __is_active_jprobe(unsigned long addr);
extern int skip_singlestep(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb);
#else
diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c
index 7a1f99f1b47f..1b316331c2d9 100644
--- a/arch/powerpc/kernel/kprobes-ftrace.c
+++ b/arch/powerpc/kernel/kprobes-ftrace.c
@@ -25,21 +25,6 @@
#include <linux/preempt.h>
#include <linux/ftrace.h>

-/*
- * This is called from ftrace code after invoking registered handlers to
- * disambiguate regs->nip changes done by jprobes and livepatch. We check if
- * there is an active jprobe at the provided address (mcount location).
- */
-int __is_active_jprobe(unsigned long addr)
-{
- if (!preemptible()) {
- struct kprobe *p = raw_cpu_read(current_kprobe);
- return (p && (unsigned long)p->addr == addr) ? 1 : 0;
- }
-
- return 0;
-}
-
static nokprobe_inline
int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb, unsigned long orig_nip)
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index e4c5bf33970b..600678fce0a8 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -611,60 +611,6 @@ unsigned long arch_deref_entry_point(void *entry)
}
NOKPROBE_SYMBOL(arch_deref_entry_point);

-int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
-{
- struct jprobe *jp = container_of(p, struct jprobe, kp);
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
- memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
-
- /* setup return addr to the jprobe handler routine */
- regs->nip = arch_deref_entry_point(jp->entry);
-#ifdef PPC64_ELF_ABI_v2
- regs->gpr[12] = (unsigned long)jp->entry;
-#elif defined(PPC64_ELF_ABI_v1)
- regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
-#endif
-
- /*
- * jprobes use jprobe_return() which skips the normal return
- * path of the function, and this messes up the accounting of the
- * function graph tracer.
- *
- * Pause function graph tracing while performing the jprobe function.
- */
- pause_graph_tracing();
-
- return 1;
-}
-NOKPROBE_SYMBOL(setjmp_pre_handler);
-
-void __used jprobe_return(void)
-{
- asm volatile("jprobe_return_trap:\n"
- "trap\n"
- ::: "memory");
-}
-NOKPROBE_SYMBOL(jprobe_return);
-
-int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
-{
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
- if (regs->nip != ppc_kallsyms_lookup_name("jprobe_return_trap")) {
- pr_debug("longjmp_break_handler NIP (0x%lx) does not match jprobe_return_trap (0x%lx)\n",
- regs->nip, ppc_kallsyms_lookup_name("jprobe_return_trap"));
- return 0;
- }
-
- memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
- /* It's OK to start function graph tracing again */
- unpause_graph_tracing();
- preempt_enable_no_resched();
- return 1;
-}
-NOKPROBE_SYMBOL(longjmp_break_handler);
-
static struct kprobe trampoline_p = {
.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
.pre_handler = trampoline_probe_handler
diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
index 9a5b5a513604..32476a6e4e9c 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
+++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
@@ -104,39 +104,13 @@ ftrace_regs_call:
bl ftrace_stub
nop

- /* Load the possibly modified NIP */
- ld r15, _NIP(r1)
-
+ /* Load ctr with the possibly modified NIP */
+ ld r3, _NIP(r1)
+ mtctr r3
#ifdef CONFIG_LIVEPATCH
- cmpd r14, r15 /* has NIP been altered? */
+ cmpd r14, r3 /* has NIP been altered? */
#endif

-#if defined(CONFIG_LIVEPATCH) && defined(CONFIG_KPROBES_ON_FTRACE)
- /* NIP has not been altered, skip over further checks */
- beq 1f
-
- /* Check if there is an active jprobe on us */
- subi r3, r14, 4
- bl __is_active_jprobe
- nop
-
- /*
- * If r3 == 1, then this is a kprobe/jprobe.
- * else, this is livepatched function.
- *
- * The conditional branch for livepatch_handler below will use the
- * result of this comparison. For kprobe/jprobe, we just need to branch to
- * the new NIP, not call livepatch_handler. The branch below is bne, so we
- * want CR0[EQ] to be true if this is a kprobe/jprobe. Which means we want
- * CR0[EQ] = (r3 == 1).
- */
- cmpdi r3, 1
-1:
-#endif
-
- /* Load CTR with the possibly modified NIP */
- mtctr r15
-
/* Restore gprs */
REST_GPR(0,r1)
REST_10GPRS(2,r1)
@@ -154,10 +128,7 @@ ftrace_regs_call:
addi r1, r1, SWITCH_FRAME_SIZE

#ifdef CONFIG_LIVEPATCH
- /*
- * Based on the cmpd or cmpdi above, if the NIP was altered and we're
- * not on a kprobe/jprobe, then handle livepatch.
- */
+ /* Based on the cmpd above, if the NIP was altered handle livepatch */
bne- livepatch_handler
#endif