[PATCH v3 14/15] ARM: add uprobes support
David Long
dave.long at linaro.org
Tue Nov 26 21:53:33 EST 2013
From: "David A. Long" <dave.long at linaro.org>
Using Rabin Vincent's ARM uprobes patches as a base, enable uprobes
support on ARM.
Caveats:
- Thumb is not supported
- XOL abort/trap handling is not implemented
Signed-off-by: David A. Long <dave.long at linaro.org>
---
arch/arm/Kconfig | 4 +
arch/arm/include/asm/ptrace.h | 6 +
arch/arm/include/asm/thread_info.h | 5 +-
arch/arm/include/asm/uprobes.h | 34 ++++++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/signal.c | 4 +
arch/arm/kernel/uprobes-arm.c | 223 +++++++++++++++++++++++++++++++++++++
arch/arm/kernel/uprobes.c | 198 ++++++++++++++++++++++++++++++++
arch/arm/kernel/uprobes.h | 27 +++++
9 files changed, 501 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/include/asm/uprobes.h
create mode 100644 arch/arm/kernel/uprobes-arm.c
create mode 100644 arch/arm/kernel/uprobes.c
create mode 100644 arch/arm/kernel/uprobes.h
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c1f1a7e..fec5a6b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -203,6 +203,10 @@ config ZONE_DMA
config NEED_DMA_MAP_STATE
def_bool y
+config ARCH_SUPPORTS_UPROBES
+ depends on KPROBES
+ def_bool y
+
config ARCH_HAS_DMA_SET_COHERENT_MASK
bool
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 04c99f3..ee688b0a 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -80,6 +80,12 @@ static inline long regs_return_value(struct pt_regs *regs)
#define instruction_pointer(regs) (regs)->ARM_pc
+static inline void instruction_pointer_set(struct pt_regs *regs,
+ unsigned long val)
+{
+ instruction_pointer(regs) = val;
+}
+
#ifdef CONFIG_SMP
extern unsigned long profile_pc(struct pt_regs *regs);
#else
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 71a06b2..f989d7c 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -153,6 +153,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
#define TIF_SIGPENDING 0
#define TIF_NEED_RESCHED 1
#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
+#define TIF_UPROBE 7
#define TIF_SYSCALL_TRACE 8
#define TIF_SYSCALL_AUDIT 9
#define TIF_SYSCALL_TRACEPOINT 10
@@ -165,6 +166,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
+#define _TIF_UPROBE (1 << TIF_UPROBE)
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
@@ -178,7 +180,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
/*
* Change these and you break ASM code in entry-common.S
*/
-#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | _TIF_NOTIFY_RESUME)
+#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
+ _TIF_NOTIFY_RESUME | _TIF_UPROBE)
#endif /* __KERNEL__ */
#endif /* __ASM_ARM_THREAD_INFO_H */
diff --git a/arch/arm/include/asm/uprobes.h b/arch/arm/include/asm/uprobes.h
new file mode 100644
index 0000000..e5acaa3
--- /dev/null
+++ b/arch/arm/include/asm/uprobes.h
@@ -0,0 +1,34 @@
+#ifndef _ASM_UPROBES_H
+#define _ASM_UPROBES_H
+
+#include <asm/probes.h>
+
+typedef u32 uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES 4
+#define UPROBE_XOL_SLOT_BYTES 64
+
+#define UPROBE_SWBP_INSN 0xe7f001f9
+#define UPROBE_SS_INSN 0xe7f001fa
+#define UPROBE_SWBP_INSN_SIZE 4
+
+struct arch_uprobe_task {
+ u32 backup;
+};
+
+struct arch_uprobe {
+ u8 insn[MAX_UINSN_BYTES];
+ unsigned long ixol[2];
+ uprobe_opcode_t bpinsn;
+ bool simulate;
+ u32 pcreg;
+ void (*prehandler)(struct arch_uprobe *auprobe,
+ struct arch_uprobe_task *autask,
+ struct pt_regs *regs);
+ void (*posthandler)(struct arch_uprobe *auprobe,
+ struct arch_uprobe_task *autask,
+ struct pt_regs *regs);
+ struct arch_specific_insn asi;
+};
+
+#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index bb739f2..a766bcb 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o insn.o patch.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
+obj-$(CONFIG_UPROBES) += probes.o probes-arm.o uprobes.o uprobes-arm.o
obj-$(CONFIG_KPROBES) += probes.o kprobes.o kprobes-common.o patch.o
ifdef CONFIG_THUMB2_KERNEL
obj-$(CONFIG_KPROBES) += kprobes-thumb.o probes-thumb.o
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 04d6388..bd19834 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -13,6 +13,7 @@
#include <linux/personality.h>
#include <linux/uaccess.h>
#include <linux/tracehook.h>
+#include <linux/uprobes.h>
#include <asm/elf.h>
#include <asm/cacheflush.h>
@@ -590,6 +591,9 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
return restart;
}
syscall = 0;
+ } else if (thread_flags & _TIF_UPROBE) {
+ clear_thread_flag(TIF_UPROBE);
+ uprobe_notify_resume(regs);
} else {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
diff --git a/arch/arm/kernel/uprobes-arm.c b/arch/arm/kernel/uprobes-arm.c
new file mode 100644
index 0000000..0a83ad7
--- /dev/null
+++ b/arch/arm/kernel/uprobes-arm.c
@@ -0,0 +1,223 @@
+#include <linux/kernel.h>
+#include <linux/wait.h>
+#include <linux/uprobes.h>
+#include <linux/module.h>
+
+#include "probes.h"
+#include "probes-arm.h"
+#include "uprobes.h"
+
+static int uprobes_substitute_pc(unsigned long *pinsn, u32 oregs)
+{
+ probes_opcode_t insn = *pinsn;
+ probes_opcode_t temp;
+ probes_opcode_t mask;
+ int freereg;
+ u32 free = 0xffff;
+ u32 regs;
+
+ for (regs = oregs; regs; regs >>= 4, insn >>= 4) {
+ if ((regs & 0xf) == REG_TYPE_NONE)
+ continue;
+
+ free &= ~(1 << (insn & 0xf));
+ }
+
+ /* No PC, no problem */
+ if (free & (1 << 15))
+ return 15;
+
+ if (!free)
+ return -1;
+
+ /*
+ * fls instead of ffs ensures that for "ldrd r0, r1, [pc]" we would
+ * pick LR instead of R1.
+ */
+ freereg = free = fls(free) - 1;
+
+ temp = *pinsn;
+ insn = *pinsn;
+ regs = oregs;
+ mask = 0xf;
+
+ for (; regs; regs >>= 4, mask <<= 4, free <<= 4, temp >>= 4) {
+ if ((regs & 0xf) == REG_TYPE_NONE)
+ continue;
+
+ if ((temp & 0xf) != 15)
+ continue;
+
+ insn &= ~mask;
+ insn |= free & mask;
+ }
+
+ *pinsn = insn;
+ return freereg;
+}
+
+static void uprobe_set_pc(struct arch_uprobe *auprobe,
+ struct arch_uprobe_task *autask,
+ struct pt_regs *regs)
+{
+ u32 pcreg = auprobe->pcreg;
+
+ autask->backup = regs->uregs[pcreg];
+ regs->uregs[pcreg] = regs->ARM_pc + 8;
+}
+
+static void uprobe_unset_pc(struct arch_uprobe *auprobe,
+ struct arch_uprobe_task *autask,
+ struct pt_regs *regs)
+{
+ /* PC will be taken care of by common code */
+ regs->uregs[auprobe->pcreg] = autask->backup;
+}
+
+static void uprobe_aluwrite_pc(struct arch_uprobe *auprobe,
+ struct arch_uprobe_task *autask,
+ struct pt_regs *regs)
+{
+ u32 pcreg = auprobe->pcreg;
+
+ alu_write_pc(regs->uregs[pcreg], regs);
+ regs->uregs[pcreg] = autask->backup;
+}
+
+static void uprobe_write_pc(struct arch_uprobe *auprobe,
+ struct arch_uprobe_task *autask,
+ struct pt_regs *regs)
+{
+ u32 pcreg = auprobe->pcreg;
+
+ load_write_pc(regs->uregs[pcreg], regs);
+ regs->uregs[pcreg] = autask->backup;
+}
+
+enum probes_insn
+decode_pc_ro(probes_opcode_t insn, struct arch_specific_insn *asi,
+ struct decode_header *d)
+{
+ struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
+ asi);
+ struct decode_emulate *decode = (struct decode_emulate *) d;
+ u32 regs = decode->header.type_regs.bits >> DECODE_TYPE_BITS;
+ int reg;
+
+ reg = uprobes_substitute_pc(&auprobe->ixol[0], regs);
+ if (reg == 15)
+ return INSN_GOOD;
+
+ if (reg == -1)
+ return INSN_REJECTED;
+
+ auprobe->pcreg = reg;
+ auprobe->prehandler = uprobe_set_pc;
+ auprobe->posthandler = uprobe_unset_pc;
+
+ return INSN_GOOD;
+}
+
+enum probes_insn
+decode_wb_pc(probes_opcode_t insn, struct arch_specific_insn *asi,
+ struct decode_header *d, bool alu)
+{
+ struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
+ asi);
+ enum probes_insn ret = decode_pc_ro(insn, asi, d);
+
+ if (((insn >> 12) & 0xf) == 15)
+ auprobe->posthandler = alu ? uprobe_aluwrite_pc
+ : uprobe_write_pc;
+
+ return ret;
+}
+
+enum probes_insn
+decode_rd12rn16rm0rs8_rwflags(probes_opcode_t insn,
+ struct arch_specific_insn *asi,
+ struct decode_header *d)
+{
+ return decode_wb_pc(insn, asi, d, true);
+}
+
+enum probes_insn
+decode_ldr(probes_opcode_t insn, struct arch_specific_insn *asi,
+ struct decode_header *d)
+{
+ return decode_wb_pc(insn, asi, d, false);
+}
+
+enum probes_insn
+uprobe_decode_ldmstm(probes_opcode_t insn,
+ struct arch_specific_insn *asi, struct decode_header *d)
+{
+ struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe,
+ asi);
+ unsigned reglist = insn & 0xffff;
+ int rn = (insn >> 16) & 0xf;
+ int lbit = insn & (1 << 20);
+ unsigned used = reglist | (1 << rn);
+
+ if (rn == 15)
+ return INSN_REJECTED;
+
+ if (!(used & (1 << 15)))
+ return INSN_GOOD;
+
+ if (used & (1 << 14))
+ return INSN_REJECTED;
+
+ /* Use LR instead of PC */
+ insn ^= 0xc000;
+
+ auprobe->pcreg = 14;
+ auprobe->ixol[0] = insn;
+
+ auprobe->prehandler = uprobe_set_pc;
+ if (lbit)
+ auprobe->posthandler = uprobe_write_pc;
+ else
+ auprobe->posthandler = uprobe_unset_pc;
+
+ return INSN_GOOD;
+}
+
+const union decode_item uprobes_probes_actions[] = {
+ [PROBES_EMULATE_NONE] {.handler = probes_simulate_nop},
+ [PROBES_SIMULATE_NOP] = {.handler = probes_simulate_nop},
+ [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 = probes_simulate_nop},
+ [PROBES_SATURATING_ARITHMETIC] = {.handler = probes_simulate_nop},
+ [PROBES_MUL1] = {.handler = probes_simulate_nop},
+ [PROBES_MUL2] = {.handler = probes_simulate_nop},
+ [PROBES_SWP] = {.handler = probes_simulate_nop},
+ [PROBES_LDRSTRD] = {.decoder = decode_pc_ro},
+ [PROBES_LOAD_EXTRA] = {.decoder = decode_pc_ro},
+ [PROBES_LOAD] = {.decoder = decode_ldr},
+ [PROBES_STORE_EXTRA] = {.decoder = decode_pc_ro},
+ [PROBES_STORE] = {.decoder = decode_pc_ro},
+ [PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp},
+ [PROBES_DATA_PROCESSING_REG] = {
+ .decoder = decode_rd12rn16rm0rs8_rwflags},
+ [PROBES_DATA_PROCESSING_IMM] = {
+ .decoder = decode_rd12rn16rm0rs8_rwflags},
+ [PROBES_MOV_HALFWORD] = {.handler = probes_simulate_nop},
+ [PROBES_SEV] = {.handler = probes_simulate_nop},
+ [PROBES_WFE] = {.handler = probes_simulate_nop},
+ [PROBES_SATURATE] = {.handler = probes_simulate_nop},
+ [PROBES_REV] = {.handler = probes_simulate_nop},
+ [PROBES_MMI] = {.handler = probes_simulate_nop},
+ [PROBES_PACK] = {.handler = probes_simulate_nop},
+ [PROBES_EXTEND] = {.handler = probes_simulate_nop},
+ [PROBES_EXTEND_ADD] = {.handler = probes_simulate_nop},
+ [PROBES_MUL_ADD_LONG] = {.handler = probes_simulate_nop},
+ [PROBES_MUL_ADD] = {.handler = probes_simulate_nop},
+ [PROBES_BITFIELD] = {.handler = probes_simulate_nop},
+ [PROBES_BRANCH] = {.handler = simulate_bbl},
+ [PROBES_LDMSTM] = {.decoder = uprobe_decode_ldmstm}
+};
diff --git a/arch/arm/kernel/uprobes.c b/arch/arm/kernel/uprobes.c
new file mode 100644
index 0000000..d9873ef
--- /dev/null
+++ b/arch/arm/kernel/uprobes.c
@@ -0,0 +1,198 @@
+/*
+ * Copyright (C) 2012 Rabin Vincent <rabin at rab.in>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/highmem.h>
+#include <linux/sched.h>
+#include <linux/uprobes.h>
+#include <linux/notifier.h>
+
+#include <asm/opcodes.h>
+#include <asm/traps.h>
+
+#include "probes.h"
+#include "probes-arm.h"
+#include "uprobes.h"
+
+bool is_swbp_insn(uprobe_opcode_t *insn)
+{
+ return (__mem_to_opcode_arm(*insn) & 0x0fffffff) ==
+ (UPROBE_SWBP_INSN & 0x0fffffff);
+}
+
+int set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm,
+ unsigned long vaddr)
+{
+ return uprobe_write_opcode(mm, vaddr,
+ __opcode_to_mem_arm(auprobe->bpinsn));
+}
+
+bool arch_uprobe_ignore(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ if (!auprobe->asi.insn_check_cc(regs->ARM_cpsr)) {
+ regs->ARM_pc += 4;
+ return true;
+ }
+
+ return false;
+}
+
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ void *addr;
+ probes_opcode_t opcode;
+
+ if (!auprobe->simulate)
+ return false;
+
+ addr = (void *) regs->ARM_pc;
+ opcode = __mem_to_opcode_arm(*(unsigned int *) auprobe->insn);
+
+ auprobe->asi.insn_singlestep(opcode, &auprobe->asi, regs);
+
+ return true;
+}
+
+unsigned long
+arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
+ struct pt_regs *regs)
+{
+ unsigned long orig_ret_vaddr;
+
+ orig_ret_vaddr = regs->ARM_lr;
+ /* Replace the return addr with trampoline addr */
+ regs->ARM_lr = trampoline_vaddr;
+ return orig_ret_vaddr;
+}
+
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
+ unsigned long addr)
+{
+ unsigned int insn;
+ unsigned int bpinsn;
+ enum probes_insn ret;
+
+ /* Thumb not yet support */
+ if (addr & 0x3)
+ return -EINVAL;
+
+ insn = __mem_to_opcode_arm(*(unsigned int *)auprobe->insn);
+ auprobe->ixol[0] = __opcode_to_mem_arm(insn);
+ auprobe->ixol[1] = __opcode_to_mem_arm(UPROBE_SS_INSN);
+
+ ret = arm_probes_decode_insn(insn, &auprobe->asi, false,
+ uprobes_probes_actions);
+ switch (ret) {
+ case INSN_REJECTED:
+ return -EINVAL;
+
+ case INSN_GOOD_NO_SLOT:
+ auprobe->simulate = true;
+ break;
+
+ case INSN_GOOD:
+ default:
+ break;
+ }
+
+ bpinsn = UPROBE_SWBP_INSN & 0x0fffffff;
+ if (insn >= 0xe0000000)
+ bpinsn |= 0xe0000000; /* Unconditional instruction */
+ else
+ bpinsn |= insn & 0xf0000000; /* Copy condition from insn */
+
+ auprobe->bpinsn = bpinsn;
+
+ return 0;
+}
+
+int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ if (auprobe->prehandler)
+ auprobe->prehandler(auprobe, &utask->autask, regs);
+
+ regs->ARM_pc = utask->xol_vaddr;
+
+ return 0;
+}
+
+int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ regs->ARM_pc = utask->vaddr + 4;
+
+ if (auprobe->posthandler)
+ auprobe->posthandler(auprobe, &utask->autask, regs);
+
+ return 0;
+}
+
+bool arch_uprobe_xol_was_trapped(struct task_struct *t)
+{
+ /* TODO: implement */
+ return false;
+}
+
+void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ /* TODO: implement */
+}
+
+int arch_uprobe_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ return NOTIFY_DONE;
+}
+
+static int uprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ instr &= 0x0fffffff;
+ if (instr == (UPROBE_SWBP_INSN & 0x0fffffff))
+ uprobe_pre_sstep_notifier(regs);
+ else if (instr == (UPROBE_SS_INSN & 0x0fffffff))
+ uprobe_post_sstep_notifier(regs);
+ local_irq_restore(flags);
+
+ return 0;
+}
+
+unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+static struct undef_hook uprobes_arm_break_hook = {
+ .instr_mask = 0x0fffffff,
+ .instr_val = (UPROBE_SWBP_INSN & 0x0fffffff),
+ .cpsr_mask = MODE_MASK,
+ .cpsr_val = USR_MODE,
+ .fn = uprobe_trap_handler,
+};
+
+static struct undef_hook uprobes_arm_ss_hook = {
+ .instr_mask = 0x0fffffff,
+ .instr_val = (UPROBE_SS_INSN & 0x0fffffff),
+ .cpsr_mask = MODE_MASK,
+ .cpsr_val = USR_MODE,
+ .fn = uprobe_trap_handler,
+};
+
+static int arch_uprobes_init(void)
+{
+ register_undef_hook(&uprobes_arm_break_hook);
+ register_undef_hook(&uprobes_arm_ss_hook);
+
+ return 0;
+}
+device_initcall(arch_uprobes_init);
diff --git a/arch/arm/kernel/uprobes.h b/arch/arm/kernel/uprobes.h
new file mode 100644
index 0000000..993af0d
--- /dev/null
+++ b/arch/arm/kernel/uprobes.h
@@ -0,0 +1,27 @@
+#ifndef __ARM_KERNEL_UPROBES_H
+#define __ARM_KERNEL_UPROBES_H
+
+enum probes_insn uprobe_decode_ldmstm(probes_opcode_t insn,
+ struct arch_specific_insn *asi,
+ struct decode_header *d);
+
+enum probes_insn decode_ldr(probes_opcode_t insn,
+ struct arch_specific_insn *asi,
+ struct decode_header *d);
+
+enum probes_insn
+decode_rd12rn16rm0rs8_rwflags(probes_opcode_t insn,
+ struct arch_specific_insn *asi,
+ struct decode_header *d);
+
+enum probes_insn
+decode_wb_pc(probes_opcode_t insn, struct arch_specific_insn *asi,
+ struct decode_header *d, bool alu);
+
+enum probes_insn
+decode_pc_ro(probes_opcode_t insn, struct arch_specific_insn *asi,
+ struct decode_header *d);
+
+extern const union decode_item uprobes_probes_actions[];
+
+#endif
--
1.8.1.2
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