Merge branch 'uprobes-v7' of git://git.linaro.org/people/dave.long/linux into devel-stable

This patch series adds basic uprobes support to ARM. It is based on
patches developed earlier by Rabin Vincent. That approach of adding
hooks into the kprobes instruction parsing code was not well received.
This approach separates the ARM instruction parsing code in kprobes out
into a separate set of functions which can be used by both kprobes and
uprobes. Both kprobes and uprobes then provide their own semantic action
tables to process the results of the parsing.

1 files changed, 30 insertions, 439 deletions

diff --git a/arch/arm/kernel/kprobes-common.c b/arch/arm/kernel/kprobes-common.c
index 18a76282970e..c311ed94ff1c 100644
--- a/arch/arm/kernel/kprobes-common.c
+++ b/arch/arm/kernel/kprobes-common.c
@@ -13,178 +13,14 @@
 
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
-#include <asm/system_info.h>
 
 #include "kprobes.h"
 
 
-#ifndef find_str_pc_offset
-
-/*
- * For STR and STM instructions, an ARM core may choose to use either
- * a +8 or a +12 displacement from the current instruction's address.
- * Whichever value is chosen for a given core, it must be the same for
- * both instructions and may not change.  This function measures it.
- */
-
-int str_pc_offset;
-
-void __init find_str_pc_offset(void)
-{
-	int addr, scratch, ret;
-
-	__asm__ (
-		"sub	%[ret], pc, #4		\n\t"
-		"str	pc, %[addr]		\n\t"
-		"ldr	%[scr], %[addr]		\n\t"
-		"sub	%[ret], %[scr], %[ret]	\n\t"
-		: [ret] "=r" (ret), [scr] "=r" (scratch), [addr] "+m" (addr));
-
-	str_pc_offset = ret;
-}
-
-#endif /* !find_str_pc_offset */
-
-
-#ifndef test_load_write_pc_interworking
-
-bool load_write_pc_interworks;
-
-void __init test_load_write_pc_interworking(void)
-{
-	int arch = cpu_architecture();
-	BUG_ON(arch == CPU_ARCH_UNKNOWN);
-	load_write_pc_interworks = arch >= CPU_ARCH_ARMv5T;
-}
-
-#endif /* !test_load_write_pc_interworking */
-
-
-#ifndef test_alu_write_pc_interworking
-
-bool alu_write_pc_interworks;
-
-void __init test_alu_write_pc_interworking(void)
-{
-	int arch = cpu_architecture();
-	BUG_ON(arch == CPU_ARCH_UNKNOWN);
-	alu_write_pc_interworks = arch >= CPU_ARCH_ARMv7;
-}
-
-#endif /* !test_alu_write_pc_interworking */
-
-
-void __init arm_kprobe_decode_init(void)
-{
-	find_str_pc_offset();
-	test_load_write_pc_interworking();
-	test_alu_write_pc_interworking();
-}
-
-
-static unsigned long __kprobes __check_eq(unsigned long cpsr)
-{
-	return cpsr & PSR_Z_BIT;
-}
-
-static unsigned long __kprobes __check_ne(unsigned long cpsr)
-{
-	return (~cpsr) & PSR_Z_BIT;
-}
-
-static unsigned long __kprobes __check_cs(unsigned long cpsr)
-{
-	return cpsr & PSR_C_BIT;
-}
-
-static unsigned long __kprobes __check_cc(unsigned long cpsr)
-{
-	return (~cpsr) & PSR_C_BIT;
-}
-
-static unsigned long __kprobes __check_mi(unsigned long cpsr)
-{
-	return cpsr & PSR_N_BIT;
-}
-
-static unsigned long __kprobes __check_pl(unsigned long cpsr)
-{
-	return (~cpsr) & PSR_N_BIT;
-}
-
-static unsigned long __kprobes __check_vs(unsigned long cpsr)
-{
-	return cpsr & PSR_V_BIT;
-}
-
-static unsigned long __kprobes __check_vc(unsigned long cpsr)
-{
-	return (~cpsr) & PSR_V_BIT;
-}
-
-static unsigned long __kprobes __check_hi(unsigned long cpsr)
-{
-	cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
-	return cpsr & PSR_C_BIT;
-}
-
-static unsigned long __kprobes __check_ls(unsigned long cpsr)
-{
-	cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
-	return (~cpsr) & PSR_C_BIT;
-}
-
-static unsigned long __kprobes __check_ge(unsigned long cpsr)
-{
-	cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
-	return (~cpsr) & PSR_N_BIT;
-}
-
-static unsigned long __kprobes __check_lt(unsigned long cpsr)
-{
-	cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
-	return cpsr & PSR_N_BIT;
-}
-
-static unsigned long __kprobes __check_gt(unsigned long cpsr)
-{
-	unsigned long temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
-	temp |= (cpsr << 1);			 /* PSR_N_BIT |= PSR_Z_BIT */
-	return (~temp) & PSR_N_BIT;
-}
-
-static unsigned long __kprobes __check_le(unsigned long cpsr)
-{
-	unsigned long temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
-	temp |= (cpsr << 1);			 /* PSR_N_BIT |= PSR_Z_BIT */
-	return temp & PSR_N_BIT;
-}
-
-static unsigned long __kprobes __check_al(unsigned long cpsr)
-{
-	return true;
-}
-
-kprobe_check_cc * const kprobe_condition_checks[16] = {
-	&__check_eq, &__check_ne, &__check_cs, &__check_cc,
-	&__check_mi, &__check_pl, &__check_vs, &__check_vc,
-	&__check_hi, &__check_ls, &__check_ge, &__check_lt,
-	&__check_gt, &__check_le, &__check_al, &__check_al
-};
-
-
-void __kprobes kprobe_simulate_nop(struct kprobe *p, struct pt_regs *regs)
-{
-}
-
-void __kprobes kprobe_emulate_none(struct kprobe *p, struct pt_regs *regs)
-{
-	p->ainsn.insn_fn();
-}
-
-static void __kprobes simulate_ldm1stm1(struct kprobe *p, struct pt_regs *regs)
+static void __kprobes simulate_ldm1stm1(probes_opcode_t insn,
+		struct arch_probes_insn *asi,
+		struct pt_regs *regs)
 {
-	kprobe_opcode_t insn = p->opcode;
 	int rn = (insn >> 16) & 0xf;
 	int lbit = insn & (1 << 20);
 	int wbit = insn & (1 << 21);
@@ -223,24 +59,31 @@ static void __kprobes simulate_ldm1stm1(struct kprobe *p, struct pt_regs *regs)
 	}
 }
 
-static void __kprobes simulate_stm1_pc(struct kprobe *p, struct pt_regs *regs)
+static void __kprobes simulate_stm1_pc(probes_opcode_t insn,
+	struct arch_probes_insn *asi,
+	struct pt_regs *regs)
 {
-	regs->ARM_pc = (long)p->addr + str_pc_offset;
-	simulate_ldm1stm1(p, regs);
-	regs->ARM_pc = (long)p->addr + 4;
+	unsigned long addr = regs->ARM_pc - 4;
+
+	regs->ARM_pc = (long)addr + str_pc_offset;
+	simulate_ldm1stm1(insn, asi, regs);
+	regs->ARM_pc = (long)addr + 4;
 }
 
-static void __kprobes simulate_ldm1_pc(struct kprobe *p, struct pt_regs *regs)
+static void __kprobes simulate_ldm1_pc(probes_opcode_t insn,
+	struct arch_probes_insn *asi,
+	struct pt_regs *regs)
 {
-	simulate_ldm1stm1(p, regs);
+	simulate_ldm1stm1(insn, asi, regs);
 	load_write_pc(regs->ARM_pc, regs);
 }
 
 static void __kprobes
-emulate_generic_r0_12_noflags(struct kprobe *p, struct pt_regs *regs)
+emulate_generic_r0_12_noflags(probes_opcode_t insn,
+	struct arch_probes_insn *asi, struct pt_regs *regs)
 {
 	register void *rregs asm("r1") = regs;
-	register void *rfn asm("lr") = p->ainsn.insn_fn;
+	register void *rfn asm("lr") = asi->insn_fn;
 
 	__asm__ __volatile__ (
 		"stmdb	sp!, {%[regs], r11}	\n\t"
@@ -264,22 +107,27 @@ emulate_generic_r0_12_noflags(struct kprobe *p, struct pt_regs *regs)
 }
 
 static void __kprobes
-emulate_generic_r2_14_noflags(struct kprobe *p, struct pt_regs *regs)
+emulate_generic_r2_14_noflags(probes_opcode_t insn,
+	struct arch_probes_insn *asi, struct pt_regs *regs)
 {
-	emulate_generic_r0_12_noflags(p, (struct pt_regs *)(regs->uregs+2));
+	emulate_generic_r0_12_noflags(insn, asi,
+		(struct pt_regs *)(regs->uregs+2));
 }
 
 static void __kprobes
-emulate_ldm_r3_15(struct kprobe *p, struct pt_regs *regs)
+emulate_ldm_r3_15(probes_opcode_t insn,
+	struct arch_probes_insn *asi, struct pt_regs *regs)
 {
-	emulate_generic_r0_12_noflags(p, (struct pt_regs *)(regs->uregs+3));
+	emulate_generic_r0_12_noflags(insn, asi,
+		(struct pt_regs *)(regs->uregs+3));
 	load_write_pc(regs->ARM_pc, regs);
 }
 
-enum kprobe_insn __kprobes
-kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi)
+enum probes_insn __kprobes
+kprobe_decode_ldmstm(probes_opcode_t insn, struct arch_probes_insn *asi,
+		const struct decode_header *h)
 {
-	kprobe_insn_handler_t *handler = 0;
+	probes_insn_handler_t *handler = 0;
 	unsigned reglist = insn & 0xffff;
 	int is_ldm = insn & 0x100000;
 	int rn = (insn >> 16) & 0xf;
@@ -319,260 +167,3 @@ kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi)
 	return INSN_GOOD_NO_SLOT;
 }
 
-
-/*
- * Prepare an instruction slot to receive an instruction for emulating.
- * This is done by placing a subroutine return after the location where the
- * instruction will be placed. We also modify ARM instructions to be
- * unconditional as the condition code will already be checked before any
- * emulation handler is called.
- */
-static kprobe_opcode_t __kprobes
-prepare_emulated_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi,
-								bool thumb)
-{
-#ifdef CONFIG_THUMB2_KERNEL
-	if (thumb) {
-		u16 *thumb_insn = (u16 *)asi->insn;
-		thumb_insn[1] = 0x4770; /* Thumb bx lr */
-		thumb_insn[2] = 0x4770; /* Thumb bx lr */
-		return insn;
-	}
-	asi->insn[1] = 0xe12fff1e; /* ARM bx lr */
-#else
-	asi->insn[1] = 0xe1a0f00e; /* mov pc, lr */
-#endif
-	/* Make an ARM instruction unconditional */
-	if (insn < 0xe0000000)
-		insn = (insn | 0xe0000000) & ~0x10000000;
-	return insn;
-}
-
-/*
- * Write a (probably modified) instruction into the slot previously prepared by
- * prepare_emulated_insn
- */
-static void  __kprobes
-set_emulated_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi,
-								bool thumb)
-{
-#ifdef CONFIG_THUMB2_KERNEL
-	if (thumb) {
-		u16 *ip = (u16 *)asi->insn;
-		if (is_wide_instruction(insn))
-			*ip++ = insn >> 16;
-		*ip++ = insn;
-		return;
-	}
-#endif
-	asi->insn[0] = insn;
-}
-
-/*
- * When we modify the register numbers encoded in an instruction to be emulated,
- * the new values come from this define. For ARM and 32-bit Thumb instructions
- * this gives...
- *
- *	bit position	  16  12   8   4   0
- *	---------------+---+---+---+---+---+
- *	register	 r2  r0  r1  --  r3
- */
-#define INSN_NEW_BITS		0x00020103
-
-/* Each nibble has same value as that at INSN_NEW_BITS bit 16 */
-#define INSN_SAMEAS16_BITS	0x22222222
-
-/*
- * Validate and modify each of the registers encoded in an instruction.
- *
- * Each nibble in regs contains a value from enum decode_reg_type. For each
- * non-zero value, the corresponding nibble in pinsn is validated and modified
- * according to the type.
- */
-static bool __kprobes decode_regs(kprobe_opcode_t* pinsn, u32 regs)
-{
-	kprobe_opcode_t insn = *pinsn;
-	kprobe_opcode_t mask = 0xf; /* Start at least significant nibble */
-
-	for (; regs != 0; regs >>= 4, mask <<= 4) {
-
-		kprobe_opcode_t new_bits = INSN_NEW_BITS;
-
-		switch (regs & 0xf) {
-
-		case REG_TYPE_NONE:
-			/* Nibble not a register, skip to next */
-			continue;
-
-		case REG_TYPE_ANY:
-			/* Any register is allowed */
-			break;
-
-		case REG_TYPE_SAMEAS16:
-			/* Replace register with same as at bit position 16 */
-			new_bits = INSN_SAMEAS16_BITS;
-			break;
-
-		case REG_TYPE_SP:
-			/* Only allow SP (R13) */
-			if ((insn ^ 0xdddddddd) & mask)
-				goto reject;
-			break;
-
-		case REG_TYPE_PC:
-			/* Only allow PC (R15) */
-			if ((insn ^ 0xffffffff) & mask)
-				goto reject;
-			break;
-
-		case REG_TYPE_NOSP:
-			/* Reject SP (R13) */
-			if (((insn ^ 0xdddddddd) & mask) == 0)
-				goto reject;
-			break;
-
-		case REG_TYPE_NOSPPC:
-		case REG_TYPE_NOSPPCX:
-			/* Reject SP and PC (R13 and R15) */
-			if (((insn ^ 0xdddddddd) & 0xdddddddd & mask) == 0)
-				goto reject;
-			break;
-
-		case REG_TYPE_NOPCWB:
-			if (!is_writeback(insn))
-				break; /* No writeback, so any register is OK */
-			/* fall through... */
-		case REG_TYPE_NOPC:
-		case REG_TYPE_NOPCX:
-			/* Reject PC (R15) */
-			if (((insn ^ 0xffffffff) & mask) == 0)
-				goto reject;
-			break;
-		}
-
-		/* Replace value of nibble with new register number... */
-		insn &= ~mask;
-		insn |= new_bits & mask;
-	}
-
-	*pinsn = insn;
-	return true;
-
-reject:
-	return false;
-}
-
-static const int decode_struct_sizes[NUM_DECODE_TYPES] = {
-	[DECODE_TYPE_TABLE]	= sizeof(struct decode_table),
-	[DECODE_TYPE_CUSTOM]	= sizeof(struct decode_custom),
-	[DECODE_TYPE_SIMULATE]	= sizeof(struct decode_simulate),
-	[DECODE_TYPE_EMULATE]	= sizeof(struct decode_emulate),
-	[DECODE_TYPE_OR]	= sizeof(struct decode_or),
-	[DECODE_TYPE_REJECT]	= sizeof(struct decode_reject)
-};
-
-/*
- * kprobe_decode_insn operates on data tables in order to decode an ARM
- * architecture instruction onto which a kprobe has been placed.
- *
- * These instruction decoding tables are a concatenation of entries each
- * of which consist of one of the following structs:
- *
- *	decode_table
- *	decode_custom
- *	decode_simulate
- *	decode_emulate
- *	decode_or
- *	decode_reject
- *
- * Each of these starts with a struct decode_header which has the following
- * fields:
- *
- *	type_regs
- *	mask
- *	value
- *
- * The least significant DECODE_TYPE_BITS of type_regs contains a value
- * from enum decode_type, this indicates which of the decode_* structs
- * the entry contains. The value DECODE_TYPE_END indicates the end of the
- * table.
- *
- * When the table is parsed, each entry is checked in turn to see if it
- * matches the instruction to be decoded using the test:
- *
- *	(insn & mask) == value
- *
- * If no match is found before the end of the table is reached then decoding
- * fails with INSN_REJECTED.
- *
- * When a match is found, decode_regs() is called to validate and modify each
- * of the registers encoded in the instruction; the data it uses to do this
- * is (type_regs >> DECODE_TYPE_BITS). A validation failure will cause decoding
- * to fail with INSN_REJECTED.
- *
- * Once the instruction has passed the above tests, further processing
- * depends on the type of the table entry's decode struct.
- *
- */
-int __kprobes
-kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi,
-				const union decode_item *table, bool thumb)
-{
-	const struct decode_header *h = (struct decode_header *)table;
-	const struct decode_header *next;
-	bool matched = false;
-
-	insn = prepare_emulated_insn(insn, asi, thumb);
-
-	for (;; h = next) {
-		enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
-		u32 regs = h->type_regs.bits >> DECODE_TYPE_BITS;
-
-		if (type == DECODE_TYPE_END)
-			return INSN_REJECTED;
-
-		next = (struct decode_header *)
-				((uintptr_t)h + decode_struct_sizes[type]);
-
-		if (!matched && (insn & h->mask.bits) != h->value.bits)
-			continue;
-
-		if (!decode_regs(&insn, regs))
-			return INSN_REJECTED;
-
-		switch (type) {
-
-		case DECODE_TYPE_TABLE: {
-			struct decode_table *d = (struct decode_table *)h;
-			next = (struct decode_header *)d->table.table;
-			break;
-		}
-
-		case DECODE_TYPE_CUSTOM: {
-			struct decode_custom *d = (struct decode_custom *)h;
-			return (*d->decoder.decoder)(insn, asi);
-		}
-
-		case DECODE_TYPE_SIMULATE: {
-			struct decode_simulate *d = (struct decode_simulate *)h;
-			asi->insn_handler = d->handler.handler;
-			return INSN_GOOD_NO_SLOT;
-		}
-
-		case DECODE_TYPE_EMULATE: {
-			struct decode_emulate *d = (struct decode_emulate *)h;
-			asi->insn_handler = d->handler.handler;
-			set_emulated_insn(insn, asi, thumb);
-			return INSN_GOOD;
-		}
-
-		case DECODE_TYPE_OR:
-			matched = true;
-			break;
-
-		case DECODE_TYPE_REJECT:
-		default:
-			return INSN_REJECTED;
-		}
-		}
-	}