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s390: support KPROBES_ON_FTRACE

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Instead of using our own kprobes-on-ftrace handling convert the
code to support KPROBES_ON_FTRACE.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Sven Schnelle
2020-01-21 12:31:47 +01:00
committed by Vasily Gorbik
parent 5f490a520b
commit 657480d9c0
6 changed files with 58 additions and 91 deletions
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59
arch/s390/kernel/kprobes.c
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@@ -56,21 +56,10 @@ struct kprobe_insn_cache kprobe_s390_insn_slots = {
static void copy_instruction(struct kprobe *p)
{
unsigned long ip = (unsigned long) p->addr;
s64 disp, new_disp;
u64 addr, new_addr;
if (ftrace_location(ip) == ip) {
/*
* If kprobes patches the instruction that is morphed by
* ftrace make sure that kprobes always sees the branch
* "jg .+24" that skips the mcount block or the "brcl 0,0"
* in case of hotpatch.
*/
ftrace_generate_nop_insn((struct ftrace_insn *)p->ainsn.insn);
p->ainsn.is_ftrace_insn = 1;
} else
memcpy(p->ainsn.insn, p->addr, insn_length(*p->addr >> 8));
memcpy(p->ainsn.insn, p->addr, insn_length(*p->addr >> 8));
p->opcode = p->ainsn.insn[0];
if (!probe_is_insn_relative_long(p->ainsn.insn))
return;
@@ -136,11 +125,6 @@ int arch_prepare_kprobe(struct kprobe *p)
}
NOKPROBE_SYMBOL(arch_prepare_kprobe);
int arch_check_ftrace_location(struct kprobe *p)
{
return 0;
}
struct swap_insn_args {
struct kprobe *p;
unsigned int arm_kprobe : 1;
@@ -149,28 +133,11 @@ struct swap_insn_args {
static int swap_instruction(void *data)
{
struct swap_insn_args *args = data;
struct ftrace_insn new_insn, *insn;
struct kprobe *p = args->p;
size_t len;
u16 opc;
new_insn.opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;
len = sizeof(new_insn.opc);
if (!p->ainsn.is_ftrace_insn)
goto skip_ftrace;
len = sizeof(new_insn);
insn = (struct ftrace_insn *) p->addr;
if (args->arm_kprobe) {
if (is_ftrace_nop(insn))
new_insn.disp = KPROBE_ON_FTRACE_NOP;
else
new_insn.disp = KPROBE_ON_FTRACE_CALL;
} else {
ftrace_generate_call_insn(&new_insn, (unsigned long)p->addr);
if (insn->disp == KPROBE_ON_FTRACE_NOP)
ftrace_generate_nop_insn(&new_insn);
}
skip_ftrace:
s390_kernel_write(p->addr, &new_insn, len);
opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;
s390_kernel_write(p->addr, &opc, sizeof(opc));
return 0;
}
NOKPROBE_SYMBOL(swap_instruction);
@@ -464,24 +431,6 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs)
unsigned long ip = regs->psw.addr;
int fixup = probe_get_fixup_type(p->ainsn.insn);
/* Check if the kprobes location is an enabled ftrace caller */
if (p->ainsn.is_ftrace_insn) {
struct ftrace_insn *insn = (struct ftrace_insn *) p->addr;
struct ftrace_insn call_insn;
ftrace_generate_call_insn(&call_insn, (unsigned long) p->addr);
/*
* A kprobe on an enabled ftrace call site actually single
* stepped an unconditional branch (ftrace nop equivalent).
* Now we need to fixup things and pretend that a brasl r0,...
* was executed instead.
*/
if (insn->disp == KPROBE_ON_FTRACE_CALL) {
ip += call_insn.disp * 2 - MCOUNT_INSN_SIZE;
regs->gprs[0] = (unsigned long)p->addr + sizeof(*insn);
}
}
if (fixup & FIXUP_PSW_NORMAL)
ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;