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acrn-kernel/arch/s390/kernel/uprobes.c

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// SPDX-License-Identifier: GPL-2.0
/*
* User-space Probes (UProbes) for s390
*
* Copyright IBM Corp. 2014
* Author(s): Jan Willeke,
*/
#include <linux/uaccess.h>
#include <linux/uprobes.h>
#include <linux/compat.h>
#include <linux/kdebug.h>
#include <linux/sched/task_stack.h>
#include <asm/switch_to.h>
#include <asm/facility.h>
#include <asm/kprobes.h>
#include <asm/dis.h>
#include "entry.h"
#define UPROBE_TRAP_NR UINT_MAX
int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
unsigned long addr)
{
return probe_is_prohibited_opcode(auprobe->insn);
}
int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
if (psw_bits(regs->psw).eaba == PSW_BITS_AMODE_24BIT)
return -EINVAL;
if (!is_compat_task() && psw_bits(regs->psw).eaba == PSW_BITS_AMODE_31BIT)
return -EINVAL;
clear_pt_regs_flag(regs, PIF_PER_TRAP);
auprobe->saved_per = psw_bits(regs->psw).per;
auprobe->saved_int_code = regs->int_code;
regs->int_code = UPROBE_TRAP_NR;
regs->psw.addr = current->utask->xol_vaddr;
set_tsk_thread_flag(current, TIF_UPROBE_SINGLESTEP);
update_cr_regs(current);
return 0;
}
bool arch_uprobe_xol_was_trapped(struct task_struct *tsk)
{
struct pt_regs *regs = task_pt_regs(tsk);
if (regs->int_code != UPROBE_TRAP_NR)
return true;
return false;
}
static int check_per_event(unsigned short cause, unsigned long control,
struct pt_regs *regs)
{
if (!(regs->psw.mask & PSW_MASK_PER))
return 0;
/* user space single step */
if (control == 0)
return 1;
/* over indication for storage alteration */
if ((control & 0x20200000) && (cause & 0x2000))
return 1;
if (cause & 0x8000) {
/* all branches */
if ((control & 0x80800000) == 0x80000000)
return 1;
/* branch into selected range */
if (((control & 0x80800000) == 0x80800000) &&
regs->psw.addr >= current->thread.per_user.start &&
regs->psw.addr <= current->thread.per_user.end)
return 1;
}
return 0;
}
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
int fixup = probe_get_fixup_type(auprobe->insn);
struct uprobe_task *utask = current->utask;
clear_tsk_thread_flag(current, TIF_UPROBE_SINGLESTEP);
update_cr_regs(current);
psw_bits(regs->psw).per = auprobe->saved_per;
regs->int_code = auprobe->saved_int_code;
if (fixup & FIXUP_PSW_NORMAL)
regs->psw.addr += utask->vaddr - utask->xol_vaddr;
if (fixup & FIXUP_RETURN_REGISTER) {
int reg = (auprobe->insn[0] & 0xf0) >> 4;
regs->gprs[reg] += utask->vaddr - utask->xol_vaddr;
}
if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
int ilen = insn_length(auprobe->insn[0] >> 8);
if (regs->psw.addr - utask->xol_vaddr == ilen)
regs->psw.addr = utask->vaddr + ilen;
}
if (check_per_event(current->thread.per_event.cause,
current->thread.per_user.control, regs)) {
/* fix per address */
current->thread.per_event.address = utask->vaddr;
/* trigger per event */
set_pt_regs_flag(regs, PIF_PER_TRAP);
}
return 0;
}
int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val,
void *data)
{
struct die_args *args = data;
struct pt_regs *regs = args->regs;
if (!user_mode(regs))
return NOTIFY_DONE;
if (regs->int_code & 0x200) /* Trap during transaction */
return NOTIFY_DONE;
switch (val) {
case DIE_BPT:
if (uprobe_pre_sstep_notifier(regs))
return NOTIFY_STOP;
break;
case DIE_SSTEP:
if (uprobe_post_sstep_notifier(regs))
return NOTIFY_STOP;
default:
break;
}
return NOTIFY_DONE;
}
void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
clear_thread_flag(TIF_UPROBE_SINGLESTEP);
regs->int_code = auprobe->saved_int_code;
regs->psw.addr = current->utask->vaddr;
current->thread.per_event.address = current->utask->vaddr;
}
unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline,
struct pt_regs *regs)
{
unsigned long orig;
orig = regs->gprs[14];
regs->gprs[14] = trampoline;
return orig;
}
bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
struct pt_regs *regs)
{
if (ctx == RP_CHECK_CHAIN_CALL)
return user_stack_pointer(regs) <= ret->stack;
else
return user_stack_pointer(regs) < ret->stack;
}
/* Instruction Emulation */
static void adjust_psw_addr(psw_t *psw, unsigned long len)
{
psw->addr = __rewind_psw(*psw, -len);
}
#define EMU_ILLEGAL_OP 1
#define EMU_SPECIFICATION 2
#define EMU_ADDRESSING 3
#define emu_load_ril(ptr, output) \
({ \
unsigned int mask = sizeof(*(ptr)) - 1; \
__typeof__(*(ptr)) input; \
int __rc = 0; \
\
if (!test_facility(34)) \
__rc = EMU_ILLEGAL_OP; \
else if ((u64 __force)ptr & mask) \
__rc = EMU_SPECIFICATION; \
else if (get_user(input, ptr)) \
__rc = EMU_ADDRESSING; \
else \
*(output) = input; \
__rc; \
})
#define emu_store_ril(regs, ptr, input) \
({ \
unsigned int mask = sizeof(*(ptr)) - 1; \
__typeof__(ptr) __ptr = (ptr); \
int __rc = 0; \
\
if (!test_facility(34)) \
__rc = EMU_ILLEGAL_OP; \
else if ((u64 __force)__ptr & mask) \
__rc = EMU_SPECIFICATION; \
else if (put_user(*(input), __ptr)) \
__rc = EMU_ADDRESSING; \
if (__rc == 0) \
sim_stor_event(regs, \
(void __force *)__ptr, \
mask + 1); \
__rc; \
})
#define emu_cmp_ril(regs, ptr, cmp) \
({ \
unsigned int mask = sizeof(*(ptr)) - 1; \
__typeof__(*(ptr)) input; \
int __rc = 0; \
\
if (!test_facility(34)) \
__rc = EMU_ILLEGAL_OP; \
else if ((u64 __force)ptr & mask) \
__rc = EMU_SPECIFICATION; \
else if (get_user(input, ptr)) \
__rc = EMU_ADDRESSING; \
else if (input > *(cmp)) \
psw_bits((regs)->psw).cc = 1; \
else if (input < *(cmp)) \
psw_bits((regs)->psw).cc = 2; \
else \
psw_bits((regs)->psw).cc = 0; \
__rc; \
})
struct insn_ril {
u8 opc0;
u8 reg : 4;
u8 opc1 : 4;
s32 disp;
} __packed;
union split_register {
u64 u64;
u32 u32[2];
u16 u16[4];
s64 s64;
s32 s32[2];
s16 s16[4];
};
/*
* If user per registers are setup to trace storage alterations and an
* emulated store took place on a fitting address a user trap is generated.
*/
static void sim_stor_event(struct pt_regs *regs, void *addr, int len)
{
if (!(regs->psw.mask & PSW_MASK_PER))
return;
if (!(current->thread.per_user.control & PER_EVENT_STORE))
return;
if ((void *)current->thread.per_user.start > (addr + len))
return;
if ((void *)current->thread.per_user.end < addr)
return;
current->thread.per_event.address = regs->psw.addr;
current->thread.per_event.cause = PER_EVENT_STORE >> 16;
set_pt_regs_flag(regs, PIF_PER_TRAP);
}
/*
* pc relative instructions are emulated, since parameters may not be
* accessible from the xol area due to range limitations.
*/
static void handle_insn_ril(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
union split_register *rx;
struct insn_ril *insn;
unsigned int ilen;
void *uptr;
int rc = 0;
insn = (struct insn_ril *) &auprobe->insn;
rx = (union split_register *) &regs->gprs[insn->reg];
uptr = (void *)(regs->psw.addr + (insn->disp * 2));
ilen = insn_length(insn->opc0);
switch (insn->opc0) {
case 0xc0:
switch (insn->opc1) {
case 0x00: /* larl */
rx->u64 = (unsigned long)uptr;
break;
}
break;
case 0xc4:
switch (insn->opc1) {
case 0x02: /* llhrl */
rc = emu_load_ril((u16 __user *)uptr, &rx->u32[1]);
break;
case 0x04: /* lghrl */
rc = emu_load_ril((s16 __user *)uptr, &rx->u64);
break;
case 0x05: /* lhrl */
rc = emu_load_ril((s16 __user *)uptr, &rx->u32[1]);
break;
case 0x06: /* llghrl */
rc = emu_load_ril((u16 __user *)uptr, &rx->u64);
break;
case 0x08: /* lgrl */
rc = emu_load_ril((u64 __user *)uptr, &rx->u64);
break;
case 0x0c: /* lgfrl */
rc = emu_load_ril((s32 __user *)uptr, &rx->u64);
break;
case 0x0d: /* lrl */
rc = emu_load_ril((u32 __user *)uptr, &rx->u32[1]);
break;
case 0x0e: /* llgfrl */
rc = emu_load_ril((u32 __user *)uptr, &rx->u64);
break;
case 0x07: /* sthrl */
rc = emu_store_ril(regs, (u16 __user *)uptr, &rx->u16[3]);
break;
case 0x0b: /* stgrl */
rc = emu_store_ril(regs, (u64 __user *)uptr, &rx->u64);
break;
case 0x0f: /* strl */
rc = emu_store_ril(regs, (u32 __user *)uptr, &rx->u32[1]);
break;
}
break;
case 0xc6:
switch (insn->opc1) {
case 0x02: /* pfdrl */
if (!test_facility(34))
rc = EMU_ILLEGAL_OP;
break;
case 0x04: /* cghrl */
rc = emu_cmp_ril(regs, (s16 __user *)uptr, &rx->s64);
break;
case 0x05: /* chrl */
rc = emu_cmp_ril(regs, (s16 __user *)uptr, &rx->s32[1]);
break;
case 0x06: /* clghrl */
rc = emu_cmp_ril(regs, (u16 __user *)uptr, &rx->u64);
break;
case 0x07: /* clhrl */
rc = emu_cmp_ril(regs, (u16 __user *)uptr, &rx->u32[1]);
break;
case 0x08: /* cgrl */
rc = emu_cmp_ril(regs, (s64 __user *)uptr, &rx->s64);
break;
case 0x0a: /* clgrl */
rc = emu_cmp_ril(regs, (u64 __user *)uptr, &rx->u64);
break;
case 0x0c: /* cgfrl */
rc = emu_cmp_ril(regs, (s32 __user *)uptr, &rx->s64);
break;
case 0x0d: /* crl */
rc = emu_cmp_ril(regs, (s32 __user *)uptr, &rx->s32[1]);
break;
case 0x0e: /* clgfrl */
rc = emu_cmp_ril(regs, (u32 __user *)uptr, &rx->u64);
break;
case 0x0f: /* clrl */
rc = emu_cmp_ril(regs, (u32 __user *)uptr, &rx->u32[1]);
break;
}
break;
}
adjust_psw_addr(&regs->psw, ilen);
switch (rc) {
case EMU_ILLEGAL_OP:
regs->int_code = ilen << 16 | 0x0001;
do_report_trap(regs, SIGILL, ILL_ILLOPC, NULL);
break;
case EMU_SPECIFICATION:
regs->int_code = ilen << 16 | 0x0006;
do_report_trap(regs, SIGILL, ILL_ILLOPC , NULL);
break;
case EMU_ADDRESSING:
regs->int_code = ilen << 16 | 0x0005;
do_report_trap(regs, SIGSEGV, SEGV_MAPERR, NULL);
break;
}
}
bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
if ((psw_bits(regs->psw).eaba == PSW_BITS_AMODE_24BIT) ||
((psw_bits(regs->psw).eaba == PSW_BITS_AMODE_31BIT) &&
!is_compat_task())) {
regs->psw.addr = __rewind_psw(regs->psw, UPROBE_SWBP_INSN_SIZE);
do_report_trap(regs, SIGILL, ILL_ILLADR, NULL);
return true;
}
if (probe_is_insn_relative_long(auprobe->insn)) {
handle_insn_ril(auprobe, regs);
return true;
}
return false;
}
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