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-rw-r--r--arch/arm/probes/kprobes/actions-arm.c336
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diff --git a/arch/arm/probes/kprobes/actions-arm.c b/arch/arm/probes/kprobes/actions-arm.c
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+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch/arm/probes/kprobes/actions-arm.c
+ *
+ * Copyright (C) 2006, 2007 Motorola Inc.
+ */
+
+/*
+ * We do not have hardware single-stepping on ARM, This
+ * effort is further complicated by the ARM not having a
+ * "next PC" register. Instructions that change the PC
+ * can't be safely single-stepped in a MP environment, so
+ * we have a lot of work to do:
+ *
+ * In the prepare phase:
+ * *) If it is an instruction that does anything
+ * with the CPU mode, we reject it for a kprobe.
+ * (This is out of laziness rather than need. The
+ * instructions could be simulated.)
+ *
+ * *) Otherwise, decode the instruction rewriting its
+ * registers to take fixed, ordered registers and
+ * setting a handler for it to run the instruction.
+ *
+ * In the execution phase by an instruction's handler:
+ *
+ * *) If the PC is written to by the instruction, the
+ * instruction must be fully simulated in software.
+ *
+ * *) Otherwise, a modified form of the instruction is
+ * directly executed. Its handler calls the
+ * instruction in insn[0]. In insn[1] is a
+ * "mov pc, lr" to return.
+ *
+ * Before calling, load up the reordered registers
+ * from the original instruction's registers. If one
+ * of the original input registers is the PC, compute
+ * and adjust the appropriate input register.
+ *
+ * After call completes, copy the output registers to
+ * the original instruction's original registers.
+ *
+ * We don't use a real breakpoint instruction since that
+ * would have us in the kernel go from SVC mode to SVC
+ * mode losing the link register. Instead we use an
+ * undefined instruction. To simplify processing, the
+ * undefined instruction used for kprobes must be reserved
+ * exclusively for kprobes use.
+ *
+ * TODO: ifdef out some instruction decoding based on architecture.
+ */
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+
+#include "../decode-arm.h"
+#include "core.h"
+#include "checkers.h"
+
+#if __LINUX_ARM_ARCH__ >= 6
+#define BLX(reg) "blx "reg" \n\t"
+#else
+#define BLX(reg) "mov lr, pc \n\t" \
+ "mov pc, "reg" \n\t"
+#endif
+
+static void __kprobes
+emulate_ldrdstrd(probes_opcode_t insn,
+ struct arch_probes_insn *asi, struct pt_regs *regs)
+{
+ unsigned long pc = regs->ARM_pc + 4;
+ int rt = (insn >> 12) & 0xf;
+ int rn = (insn >> 16) & 0xf;
+ int rm = insn & 0xf;
+
+ register unsigned long rtv asm("r0") = regs->uregs[rt];
+ register unsigned long rt2v asm("r1") = regs->uregs[rt+1];
+ register unsigned long rnv asm("r2") = (rn == 15) ? pc
+ : regs->uregs[rn];
+ register unsigned long rmv asm("r3") = regs->uregs[rm];
+
+ __asm__ __volatile__ (
+ BLX("%[fn]")
+ : "=r" (rtv), "=r" (rt2v), "=r" (rnv)
+ : "0" (rtv), "1" (rt2v), "2" (rnv), "r" (rmv),
+ [fn] "r" (asi->insn_fn)
+ : "lr", "memory", "cc"
+ );
+
+ regs->uregs[rt] = rtv;
+ regs->uregs[rt+1] = rt2v;
+ if (is_writeback(insn))
+ regs->uregs[rn] = rnv;
+}
+
+static void __kprobes
+emulate_ldr(probes_opcode_t insn,
+ struct arch_probes_insn *asi, struct pt_regs *regs)
+{
+ unsigned long pc = regs->ARM_pc + 4;
+ int rt = (insn >> 12) & 0xf;
+ int rn = (insn >> 16) & 0xf;
+ int rm = insn & 0xf;
+
+ register unsigned long rtv asm("r0");
+ register unsigned long rnv asm("r2") = (rn == 15) ? pc
+ : regs->uregs[rn];
+ register unsigned long rmv asm("r3") = regs->uregs[rm];
+
+ __asm__ __volatile__ (
+ BLX("%[fn]")
+ : "=r" (rtv), "=r" (rnv)
+ : "1" (rnv), "r" (rmv), [fn] "r" (asi->insn_fn)
+ : "lr", "memory", "cc"
+ );
+
+ if (rt == 15)
+ load_write_pc(rtv, regs);
+ else
+ regs->uregs[rt] = rtv;
+
+ if (is_writeback(insn))
+ regs->uregs[rn] = rnv;
+}
+
+static void __kprobes
+emulate_str(probes_opcode_t insn,
+ struct arch_probes_insn *asi, struct pt_regs *regs)
+{
+ unsigned long rtpc = regs->ARM_pc - 4 + str_pc_offset;
+ unsigned long rnpc = regs->ARM_pc + 4;
+ int rt = (insn >> 12) & 0xf;
+ int rn = (insn >> 16) & 0xf;
+ int rm = insn & 0xf;
+
+ register unsigned long rtv asm("r0") = (rt == 15) ? rtpc
+ : regs->uregs[rt];
+ register unsigned long rnv asm("r2") = (rn == 15) ? rnpc
+ : regs->uregs[rn];
+ register unsigned long rmv asm("r3") = regs->uregs[rm];
+
+ __asm__ __volatile__ (
+ BLX("%[fn]")
+ : "=r" (rnv)
+ : "r" (rtv), "0" (rnv), "r" (rmv), [fn] "r" (asi->insn_fn)
+ : "lr", "memory", "cc"
+ );
+
+ if (is_writeback(insn))
+ regs->uregs[rn] = rnv;
+}
+
+static void __kprobes
+emulate_rd12rn16rm0rs8_rwflags(probes_opcode_t insn,
+ struct arch_probes_insn *asi, struct pt_regs *regs)
+{
+ unsigned long pc = regs->ARM_pc + 4;
+ int rd = (insn >> 12) & 0xf;
+ int rn = (insn >> 16) & 0xf;
+ int rm = insn & 0xf;
+ int rs = (insn >> 8) & 0xf;
+
+ register unsigned long rdv asm("r0") = regs->uregs[rd];
+ register unsigned long rnv asm("r2") = (rn == 15) ? pc
+ : regs->uregs[rn];
+ register unsigned long rmv asm("r3") = (rm == 15) ? pc
+ : regs->uregs[rm];
+ register unsigned long rsv asm("r1") = regs->uregs[rs];
+ unsigned long cpsr = regs->ARM_cpsr;
+
+ __asm__ __volatile__ (
+ "msr cpsr_fs, %[cpsr] \n\t"
+ BLX("%[fn]")
+ "mrs %[cpsr], cpsr \n\t"
+ : "=r" (rdv), [cpsr] "=r" (cpsr)
+ : "0" (rdv), "r" (rnv), "r" (rmv), "r" (rsv),
+ "1" (cpsr), [fn] "r" (asi->insn_fn)
+ : "lr", "memory", "cc"
+ );
+
+ if (rd == 15)
+ alu_write_pc(rdv, regs);
+ else
+ regs->uregs[rd] = rdv;
+ regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
+}
+
+static void __kprobes
+emulate_rd12rn16rm0_rwflags_nopc(probes_opcode_t insn,
+ struct arch_probes_insn *asi, struct pt_regs *regs)
+{
+ int rd = (insn >> 12) & 0xf;
+ int rn = (insn >> 16) & 0xf;
+ int rm = insn & 0xf;
+
+ register unsigned long rdv asm("r0") = regs->uregs[rd];
+ register unsigned long rnv asm("r2") = regs->uregs[rn];
+ register unsigned long rmv asm("r3") = regs->uregs[rm];
+ unsigned long cpsr = regs->ARM_cpsr;
+
+ __asm__ __volatile__ (
+ "msr cpsr_fs, %[cpsr] \n\t"
+ BLX("%[fn]")
+ "mrs %[cpsr], cpsr \n\t"
+ : "=r" (rdv), [cpsr] "=r" (cpsr)
+ : "0" (rdv), "r" (rnv), "r" (rmv),
+ "1" (cpsr), [fn] "r" (asi->insn_fn)
+ : "lr", "memory", "cc"
+ );
+
+ regs->uregs[rd] = rdv;
+ regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
+}
+
+static void __kprobes
+emulate_rd16rn12rm0rs8_rwflags_nopc(probes_opcode_t insn,
+ struct arch_probes_insn *asi,
+ struct pt_regs *regs)
+{
+ int rd = (insn >> 16) & 0xf;
+ int rn = (insn >> 12) & 0xf;
+ int rm = insn & 0xf;
+ int rs = (insn >> 8) & 0xf;
+
+ register unsigned long rdv asm("r2") = regs->uregs[rd];
+ register unsigned long rnv asm("r0") = regs->uregs[rn];
+ register unsigned long rmv asm("r3") = regs->uregs[rm];
+ register unsigned long rsv asm("r1") = regs->uregs[rs];
+ unsigned long cpsr = regs->ARM_cpsr;
+
+ __asm__ __volatile__ (
+ "msr cpsr_fs, %[cpsr] \n\t"
+ BLX("%[fn]")
+ "mrs %[cpsr], cpsr \n\t"
+ : "=r" (rdv), [cpsr] "=r" (cpsr)
+ : "0" (rdv), "r" (rnv), "r" (rmv), "r" (rsv),
+ "1" (cpsr), [fn] "r" (asi->insn_fn)
+ : "lr", "memory", "cc"
+ );
+
+ regs->uregs[rd] = rdv;
+ regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
+}
+
+static void __kprobes
+emulate_rd12rm0_noflags_nopc(probes_opcode_t insn,
+ struct arch_probes_insn *asi, struct pt_regs *regs)
+{
+ int rd = (insn >> 12) & 0xf;
+ int rm = insn & 0xf;
+
+ register unsigned long rdv asm("r0") = regs->uregs[rd];
+ register unsigned long rmv asm("r3") = regs->uregs[rm];
+
+ __asm__ __volatile__ (
+ BLX("%[fn]")
+ : "=r" (rdv)
+ : "0" (rdv), "r" (rmv), [fn] "r" (asi->insn_fn)
+ : "lr", "memory", "cc"
+ );
+
+ regs->uregs[rd] = rdv;
+}
+
+static void __kprobes
+emulate_rdlo12rdhi16rn0rm8_rwflags_nopc(probes_opcode_t insn,
+ struct arch_probes_insn *asi,
+ struct pt_regs *regs)
+{
+ int rdlo = (insn >> 12) & 0xf;
+ int rdhi = (insn >> 16) & 0xf;
+ int rn = insn & 0xf;
+ int rm = (insn >> 8) & 0xf;
+
+ register unsigned long rdlov asm("r0") = regs->uregs[rdlo];
+ register unsigned long rdhiv asm("r2") = regs->uregs[rdhi];
+ register unsigned long rnv asm("r3") = regs->uregs[rn];
+ register unsigned long rmv asm("r1") = regs->uregs[rm];
+ unsigned long cpsr = regs->ARM_cpsr;
+
+ __asm__ __volatile__ (
+ "msr cpsr_fs, %[cpsr] \n\t"
+ BLX("%[fn]")
+ "mrs %[cpsr], cpsr \n\t"
+ : "=r" (rdlov), "=r" (rdhiv), [cpsr] "=r" (cpsr)
+ : "0" (rdlov), "1" (rdhiv), "r" (rnv), "r" (rmv),
+ "2" (cpsr), [fn] "r" (asi->insn_fn)
+ : "lr", "memory", "cc"
+ );
+
+ regs->uregs[rdlo] = rdlov;
+ regs->uregs[rdhi] = rdhiv;
+ regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
+}
+
+const union decode_action kprobes_arm_actions[NUM_PROBES_ARM_ACTIONS] = {
+ [PROBES_PRELOAD_IMM] = {.handler = probes_simulate_nop},
+ [PROBES_PRELOAD_REG] = {.handler = probes_simulate_nop},
+ [PROBES_BRANCH_IMM] = {.handler = simulate_blx1},
+ [PROBES_MRS] = {.handler = simulate_mrs},
+ [PROBES_BRANCH_REG] = {.handler = simulate_blx2bx},
+ [PROBES_CLZ] = {.handler = emulate_rd12rm0_noflags_nopc},
+ [PROBES_SATURATING_ARITHMETIC] = {
+ .handler = emulate_rd12rn16rm0_rwflags_nopc},
+ [PROBES_MUL1] = {.handler = emulate_rdlo12rdhi16rn0rm8_rwflags_nopc},
+ [PROBES_MUL2] = {.handler = emulate_rd16rn12rm0rs8_rwflags_nopc},
+ [PROBES_SWP] = {.handler = emulate_rd12rn16rm0_rwflags_nopc},
+ [PROBES_LDRSTRD] = {.handler = emulate_ldrdstrd},
+ [PROBES_LOAD_EXTRA] = {.handler = emulate_ldr},
+ [PROBES_LOAD] = {.handler = emulate_ldr},
+ [PROBES_STORE_EXTRA] = {.handler = emulate_str},
+ [PROBES_STORE] = {.handler = emulate_str},
+ [PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp},
+ [PROBES_DATA_PROCESSING_REG] = {
+ .handler = emulate_rd12rn16rm0rs8_rwflags},
+ [PROBES_DATA_PROCESSING_IMM] = {
+ .handler = emulate_rd12rn16rm0rs8_rwflags},
+ [PROBES_MOV_HALFWORD] = {.handler = emulate_rd12rm0_noflags_nopc},
+ [PROBES_SEV] = {.handler = probes_emulate_none},
+ [PROBES_WFE] = {.handler = probes_simulate_nop},
+ [PROBES_SATURATE] = {.handler = emulate_rd12rn16rm0_rwflags_nopc},
+ [PROBES_REV] = {.handler = emulate_rd12rm0_noflags_nopc},
+ [PROBES_MMI] = {.handler = emulate_rd12rn16rm0_rwflags_nopc},
+ [PROBES_PACK] = {.handler = emulate_rd12rn16rm0_rwflags_nopc},
+ [PROBES_EXTEND] = {.handler = emulate_rd12rm0_noflags_nopc},
+ [PROBES_EXTEND_ADD] = {.handler = emulate_rd12rn16rm0_rwflags_nopc},
+ [PROBES_MUL_ADD_LONG] = {
+ .handler = emulate_rdlo12rdhi16rn0rm8_rwflags_nopc},
+ [PROBES_MUL_ADD] = {.handler = emulate_rd16rn12rm0rs8_rwflags_nopc},
+ [PROBES_BITFIELD] = {.handler = emulate_rd12rm0_noflags_nopc},
+ [PROBES_BRANCH] = {.handler = simulate_bbl},
+ [PROBES_LDMSTM] = {.decoder = kprobe_decode_ldmstm}
+};
+
+const struct decode_checker *kprobes_arm_checkers[] = {arm_stack_checker, arm_regs_checker, NULL};