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Merge branch 'perf/uprobes' into perf/core

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These bits from Oleg are fully cooked, ship them to Linus.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2014-06-05 11:18:03 +02:00
commit c56d34064b
8 changed files with 417 additions and 332 deletions
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1
arch/x86/include/asm/traps.h
View file

@ -98,7 +98,6 @@ static inline int get_si_code(unsigned long condition)
extern int panic_on_unrecovered_nmi;
void math_error(struct pt_regs *, int, int);
void math_emulate(struct math_emu_info *);
#ifndef CONFIG_X86_32
asmlinkage void smp_thermal_interrupt(void);

10
arch/x86/include/asm/uprobes.h
View file

@ -41,18 +41,18 @@ struct arch_uprobe {
u8 ixol[MAX_UINSN_BYTES];
};
u16 fixups;
const struct uprobe_xol_ops *ops;
union {
#ifdef CONFIG_X86_64
unsigned long rip_rela_target_address;
#endif
struct {
s32 offs;
u8 ilen;
u8 opc1;
} branch;
} branch;
struct {
u8 fixups;
u8 ilen;
} def;
};
};

7
arch/x86/kernel/process_64.c
View file

@ -413,12 +413,11 @@ void set_personality_ia32(bool x32)
set_thread_flag(TIF_ADDR32);
/* Mark the associated mm as containing 32-bit tasks. */
if (current->mm)
current->mm->context.ia32_compat = 1;
if (x32) {
clear_thread_flag(TIF_IA32);
set_thread_flag(TIF_X32);
if (current->mm)
current->mm->context.ia32_compat = TIF_X32;
current->personality &= ~READ_IMPLIES_EXEC;
/* is_compat_task() uses the presence of the x32
syscall bit flag to determine compat status */
@ -426,6 +425,8 @@ void set_personality_ia32(bool x32)
} else {
set_thread_flag(TIF_IA32);
clear_thread_flag(TIF_X32);
if (current->mm)
current->mm->context.ia32_compat = TIF_IA32;
current->personality |= force_personality32;
/* Prepare the first "return" to user space */
current_thread_info()->status |= TS_COMPAT;

112
arch/x86/kernel/traps.c
View file

@ -23,6 +23,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/uprobes.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/errno.h>
@ -136,6 +137,37 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
return -1;
}
static siginfo_t *fill_trap_info(struct pt_regs *regs, int signr, int trapnr,
siginfo_t *info)
{
unsigned long siaddr;
int sicode;
switch (trapnr) {
default:
return SEND_SIG_PRIV;
case X86_TRAP_DE:
sicode = FPE_INTDIV;
siaddr = uprobe_get_trap_addr(regs);
break;
case X86_TRAP_UD:
sicode = ILL_ILLOPN;
siaddr = uprobe_get_trap_addr(regs);
break;
case X86_TRAP_AC:
sicode = BUS_ADRALN;
siaddr = 0;
break;
}
info->si_signo = signr;
info->si_errno = 0;
info->si_code = sicode;
info->si_addr = (void __user *)siaddr;
return info;
}
static void __kprobes
do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
long error_code, siginfo_t *info)
@ -168,60 +200,42 @@ do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
}
#endif
if (info)
force_sig_info(signr, info, tsk);
else
force_sig(signr, tsk);
force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk);
}
static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
unsigned long trapnr, int signr)
{
enum ctx_state prev_state = exception_enter();
siginfo_t info;
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
NOTIFY_STOP) {
conditional_sti(regs);
do_trap(trapnr, signr, str, regs, error_code,
fill_trap_info(regs, signr, trapnr, &info));
}
exception_exit(prev_state);
}
#define DO_ERROR(trapnr, signr, str, name) \
dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
{ \
enum ctx_state prev_state; \
\
prev_state = exception_enter(); \
if (notify_die(DIE_TRAP, str, regs, error_code, \
trapnr, signr) == NOTIFY_STOP) { \
exception_exit(prev_state); \
return; \
} \
conditional_sti(regs); \
do_trap(trapnr, signr, str, regs, error_code, NULL); \
exception_exit(prev_state); \
do_error_trap(regs, error_code, str, trapnr, signr); \
}
#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
{ \
siginfo_t info; \
enum ctx_state prev_state; \
\
info.si_signo = signr; \
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
prev_state = exception_enter(); \
if (notify_die(DIE_TRAP, str, regs, error_code, \
trapnr, signr) == NOTIFY_STOP) { \
exception_exit(prev_state); \
return; \
} \
conditional_sti(regs); \
do_trap(trapnr, signr, str, regs, error_code, &info); \
exception_exit(prev_state); \
}
DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip )
DO_ERROR (X86_TRAP_OF, SIGSEGV, "overflow", overflow )
DO_ERROR (X86_TRAP_BR, SIGSEGV, "bounds", bounds )
DO_ERROR_INFO(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip )
DO_ERROR (X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun )
DO_ERROR (X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS )
DO_ERROR (X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present )
DO_ERROR(X86_TRAP_DE, SIGFPE, "divide error", divide_error)
DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow)
DO_ERROR(X86_TRAP_BR, SIGSEGV, "bounds", bounds)
DO_ERROR(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op)
DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",coprocessor_segment_overrun)
DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
#ifdef CONFIG_X86_32
DO_ERROR (X86_TRAP_SS, SIGBUS, "stack segment", stack_segment )
DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
#endif
DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0 )
DO_ERROR(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check)
#ifdef CONFIG_X86_64
/* Runs on IST stack */
@ -305,7 +319,7 @@ do_general_protection(struct pt_regs *regs, long error_code)
pr_cont("\n");
}
force_sig(SIGSEGV, tsk);
force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
exit:
exception_exit(prev_state);
}
@ -488,7 +502,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
* the correct behaviour even in the presence of the asynchronous
* IRQ13 behaviour
*/
void math_error(struct pt_regs *regs, int error_code, int trapnr)
static void math_error(struct pt_regs *regs, int error_code, int trapnr)
{
struct task_struct *task = current;
siginfo_t info;
@ -518,7 +532,7 @@ void math_error(struct pt_regs *regs, int error_code, int trapnr)
task->thread.error_code = error_code;
info.si_signo = SIGFPE;
info.si_errno = 0;
info.si_addr = (void __user *)regs->ip;
info.si_addr = (void __user *)uprobe_get_trap_addr(regs);
if (trapnr == X86_TRAP_MF) {
unsigned short cwd, swd;
/*
@ -645,7 +659,7 @@ void math_state_restore(void)
*/
if (unlikely(restore_fpu_checking(tsk))) {
drop_init_fpu(tsk);
force_sig(SIGSEGV, tsk);
force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
return;
}

526
arch/x86/kernel/uprobes.c
View file

@ -32,20 +32,20 @@
/* Post-execution fixups. */
/* No fixup needed */
#define UPROBE_FIX_NONE 0x0
/* Adjust IP back to vicinity of actual insn */
#define UPROBE_FIX_IP 0x1
#define UPROBE_FIX_IP 0x01
/* Adjust the return address of a call insn */
#define UPROBE_FIX_CALL 0x2
#define UPROBE_FIX_CALL 0x02
/* Instruction will modify TF, don't change it */
#define UPROBE_FIX_SETF 0x4
#define UPROBE_FIX_SETF 0x04
#define UPROBE_FIX_RIP_AX 0x8000
#define UPROBE_FIX_RIP_CX 0x4000
#define UPROBE_FIX_RIP_SI 0x08
#define UPROBE_FIX_RIP_DI 0x10
#define UPROBE_FIX_RIP_BX 0x20
#define UPROBE_FIX_RIP_MASK \
(UPROBE_FIX_RIP_SI | UPROBE_FIX_RIP_DI | UPROBE_FIX_RIP_BX)
#define UPROBE_TRAP_NR UINT_MAX
@ -67,6 +67,7 @@
* to keep gcc from statically optimizing it out, as variable_test_bit makes
* some versions of gcc to think only *(unsigned long*) is used.
*/
#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
static volatile u32 good_insns_32[256 / 32] = {
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/* ---------------------------------------------- */
@ -89,6 +90,37 @@ static volatile u32 good_insns_32[256 / 32] = {
/* ---------------------------------------------- */
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
};
#else
#define good_insns_32 NULL
#endif
/* Good-instruction tables for 64-bit apps */
#if defined(CONFIG_X86_64)
static volatile u32 good_insns_64[256 / 32] = {
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/* ---------------------------------------------- */
W(0x00, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 00 */
W(0x10, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 10 */
W(0x20, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 20 */
W(0x30, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 30 */
W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */
W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
W(0x60, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */
W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */
W(0x80, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */
W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
W(0xc0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */
W(0xd0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */
W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */
/* ---------------------------------------------- */
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
};
#else
#define good_insns_64 NULL
#endif
/* Using this for both 64-bit and 32-bit apps */
static volatile u32 good_2byte_insns[256 / 32] = {
@ -113,32 +145,6 @@ static volatile u32 good_2byte_insns[256 / 32] = {
/* ---------------------------------------------- */
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
};
#ifdef CONFIG_X86_64
/* Good-instruction tables for 64-bit apps */
static volatile u32 good_insns_64[256 / 32] = {
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/* ---------------------------------------------- */
W(0x00, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 00 */
W(0x10, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 10 */
W(0x20, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 20 */
W(0x30, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 30 */
W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */
W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
W(0x60, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */
W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */
W(0x80, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */
W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
W(0xc0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */
W(0xd0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */
W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */
/* ---------------------------------------------- */
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
};
#endif
#undef W
/*
@ -209,16 +215,25 @@ static bool is_prefix_bad(struct insn *insn)
return false;
}
static int validate_insn_32bits(struct arch_uprobe *auprobe, struct insn *insn)
static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool x86_64)
{
insn_init(insn, auprobe->insn, false);
u32 volatile *good_insns;
insn_init(insn, auprobe->insn, x86_64);
/* has the side-effect of processing the entire instruction */
insn_get_length(insn);
if (WARN_ON_ONCE(!insn_complete(insn)))
return -ENOEXEC;
/* Skip good instruction prefixes; reject "bad" ones. */
insn_get_opcode(insn);
if (is_prefix_bad(insn))
return -ENOTSUPP;
if (test_bit(OPCODE1(insn), (unsigned long *)good_insns_32))
if (x86_64)
good_insns = good_insns_64;
else
good_insns = good_insns_32;
if (test_bit(OPCODE1(insn), (unsigned long *)good_insns))
return 0;
if (insn->opcode.nbytes == 2) {
@ -230,14 +245,18 @@ static int validate_insn_32bits(struct arch_uprobe *auprobe, struct insn *insn)
}
#ifdef CONFIG_X86_64
static inline bool is_64bit_mm(struct mm_struct *mm)
{
return !config_enabled(CONFIG_IA32_EMULATION) ||
!(mm->context.ia32_compat == TIF_IA32);
}
/*
* If arch_uprobe->insn doesn't use rip-relative addressing, return
* immediately. Otherwise, rewrite the instruction so that it accesses
* its memory operand indirectly through a scratch register. Set
* arch_uprobe->fixups and arch_uprobe->rip_rela_target_address
* accordingly. (The contents of the scratch register will be saved
* before we single-step the modified instruction, and restored
* afterward.)
* def->fixups accordingly. (The contents of the scratch register
* will be saved before we single-step the modified instruction,
* and restored afterward).
*
* We do this because a rip-relative instruction can access only a
* relatively small area (+/- 2 GB from the instruction), and the XOL
@ -248,164 +267,192 @@ static int validate_insn_32bits(struct arch_uprobe *auprobe, struct insn *insn)
*
* Some useful facts about rip-relative instructions:
*
* - There's always a modrm byte.
* - There's always a modrm byte with bit layout "00 reg 101".
* - There's never a SIB byte.
* - The displacement is always 4 bytes.
* - REX.B=1 bit in REX prefix, which normally extends r/m field,
* has no effect on rip-relative mode. It doesn't make modrm byte
* with r/m=101 refer to register 1101 = R13.
*/
static void
handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn)
static void riprel_analyze(struct arch_uprobe *auprobe, struct insn *insn)
{
u8 *cursor;
u8 reg;
u8 reg2;
if (!insn_rip_relative(insn))
return;
/*
* insn_rip_relative() would have decoded rex_prefix, modrm.
* insn_rip_relative() would have decoded rex_prefix, vex_prefix, modrm.
* Clear REX.b bit (extension of MODRM.rm field):
* we want to encode rax/rcx, not r8/r9.
* we want to encode low numbered reg, not r8+.
*/
if (insn->rex_prefix.nbytes) {
cursor = auprobe->insn + insn_offset_rex_prefix(insn);
*cursor &= 0xfe; /* Clearing REX.B bit */
/* REX byte has 0100wrxb layout, clearing REX.b bit */
*cursor &= 0xfe;
}
/*
* Similar treatment for VEX3 prefix.
* TODO: add XOP/EVEX treatment when insn decoder supports them
*/
if (insn->vex_prefix.nbytes == 3) {
/*
* vex2: c5 rvvvvLpp (has no b bit)
* vex3/xop: c4/8f rxbmmmmm wvvvvLpp
* evex: 62 rxbR00mm wvvvv1pp zllBVaaa
* (evex will need setting of both b and x since
* in non-sib encoding evex.x is 4th bit of MODRM.rm)
* Setting VEX3.b (setting because it has inverted meaning):
*/
cursor = auprobe->insn + insn_offset_vex_prefix(insn) + 1;
*cursor |= 0x20;
}
/*
* Convert from rip-relative addressing to register-relative addressing
* via a scratch register.
*
* This is tricky since there are insns with modrm byte
* which also use registers not encoded in modrm byte:
* [i]div/[i]mul: implicitly use dx:ax
* shift ops: implicitly use cx
* cmpxchg: implicitly uses ax
* cmpxchg8/16b: implicitly uses dx:ax and bx:cx
* Encoding: 0f c7/1 modrm
* The code below thinks that reg=1 (cx), chooses si as scratch.
* mulx: implicitly uses dx: mulx r/m,r1,r2 does r1:r2 = dx * r/m.
* First appeared in Haswell (BMI2 insn). It is vex-encoded.
* Example where none of bx,cx,dx can be used as scratch reg:
* c4 e2 63 f6 0d disp32 mulx disp32(%rip),%ebx,%ecx
* [v]pcmpistri: implicitly uses cx, xmm0
* [v]pcmpistrm: implicitly uses xmm0
* [v]pcmpestri: implicitly uses ax, dx, cx, xmm0
* [v]pcmpestrm: implicitly uses ax, dx, xmm0
* Evil SSE4.2 string comparison ops from hell.
* maskmovq/[v]maskmovdqu: implicitly uses (ds:rdi) as destination.
* Encoding: 0f f7 modrm, 66 0f f7 modrm, vex-encoded: c5 f9 f7 modrm.
* Store op1, byte-masked by op2 msb's in each byte, to (ds:rdi).
* AMD says it has no 3-operand form (vex.vvvv must be 1111)
* and that it can have only register operands, not mem
* (its modrm byte must have mode=11).
* If these restrictions will ever be lifted,
* we'll need code to prevent selection of di as scratch reg!
*
* Summary: I don't know any insns with modrm byte which
* use SI register implicitly. DI register is used only
* by one insn (maskmovq) and BX register is used
* only by one too (cmpxchg8b).
* BP is stack-segment based (may be a problem?).
* AX, DX, CX are off-limits (many implicit users).
* SP is unusable (it's stack pointer - think about "pop mem";
* also, rsp+disp32 needs sib encoding -> insn length change).
*/
reg = MODRM_REG(insn); /* Fetch modrm.reg */
reg2 = 0xff; /* Fetch vex.vvvv */
if (insn->vex_prefix.nbytes == 2)
reg2 = insn->vex_prefix.bytes[1];
else if (insn->vex_prefix.nbytes == 3)
reg2 = insn->vex_prefix.bytes[2];
/*
* TODO: add XOP, EXEV vvvv reading.
*
* vex.vvvv field is in bits 6-3, bits are inverted.
* But in 32-bit mode, high-order bit may be ignored.
* Therefore, let's consider only 3 low-order bits.
*/
reg2 = ((reg2 >> 3) & 0x7) ^ 0x7;
/*
* Register numbering is ax,cx,dx,bx, sp,bp,si,di, r8..r15.
*
* Choose scratch reg. Order is important: must not select bx
* if we can use si (cmpxchg8b case!)
*/
if (reg != 6 && reg2 != 6) {
reg2 = 6;
auprobe->def.fixups |= UPROBE_FIX_RIP_SI;
} else if (reg != 7 && reg2 != 7) {
reg2 = 7;
auprobe->def.fixups |= UPROBE_FIX_RIP_DI;
/* TODO (paranoia): force maskmovq to not use di */
} else {
reg2 = 3;
auprobe->def.fixups |= UPROBE_FIX_RIP_BX;
}
/*
* Point cursor at the modrm byte. The next 4 bytes are the
* displacement. Beyond the displacement, for some instructions,
* is the immediate operand.
*/
cursor = auprobe->insn + insn_offset_modrm(insn);
insn_get_length(insn);
/*
* Convert from rip-relative addressing to indirect addressing
* via a scratch register. Change the r/m field from 0x5 (%rip)
* to 0x0 (%rax) or 0x1 (%rcx), and squeeze out the offset field.
* Change modrm from "00 reg 101" to "10 reg reg2". Example:
* 89 05 disp32 mov %eax,disp32(%rip) becomes
* 89 86 disp32 mov %eax,disp32(%rsi)
*/
reg = MODRM_REG(insn);
if (reg == 0) {
/*
* The register operand (if any) is either the A register
* (%rax, %eax, etc.) or (if the 0x4 bit is set in the
* REX prefix) %r8. In any case, we know the C register
* is NOT the register operand, so we use %rcx (register
* #1) for the scratch register.
*/
auprobe->fixups = UPROBE_FIX_RIP_CX;
/* Change modrm from 00 000 101 to 00 000 001. */
*cursor = 0x1;
} else {
/* Use %rax (register #0) for the scratch register. */
auprobe->fixups = UPROBE_FIX_RIP_AX;
/* Change modrm from 00 xxx 101 to 00 xxx 000 */
*cursor = (reg << 3);
}
*cursor = 0x80 | (reg << 3) | reg2;
}
/* Target address = address of next instruction + (signed) offset */
auprobe->rip_rela_target_address = (long)insn->length + insn->displacement.value;
/* Displacement field is gone; slide immediate field (if any) over. */
if (insn->immediate.nbytes) {
cursor++;
memmove(cursor, cursor + insn->displacement.nbytes, insn->immediate.nbytes);
}
static inline unsigned long *
scratch_reg(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
if (auprobe->def.fixups & UPROBE_FIX_RIP_SI)
return &regs->si;
if (auprobe->def.fixups & UPROBE_FIX_RIP_DI)
return &regs->di;
return &regs->bx;
}
/*
* If we're emulating a rip-relative instruction, save the contents
* of the scratch register and store the target address in that register.
*/
static void
pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
struct arch_uprobe_task *autask)
static void riprel_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
if (auprobe->fixups & UPROBE_FIX_RIP_AX) {
autask->saved_scratch_register = regs->ax;
regs->ax = current->utask->vaddr;
regs->ax += auprobe->rip_rela_target_address;
} else if (auprobe->fixups & UPROBE_FIX_RIP_CX) {
autask->saved_scratch_register = regs->cx;
regs->cx = current->utask->vaddr;
regs->cx += auprobe->rip_rela_target_address;
if (auprobe->def.fixups & UPROBE_FIX_RIP_MASK) {
struct uprobe_task *utask = current->utask;
unsigned long *sr = scratch_reg(auprobe, regs);
utask->autask.saved_scratch_register = *sr;
*sr = utask->vaddr + auprobe->def.ilen;
}
}
static void
handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
static void riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
if (auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {
struct arch_uprobe_task *autask;
if (auprobe->def.fixups & UPROBE_FIX_RIP_MASK) {
struct uprobe_task *utask = current->utask;
unsigned long *sr = scratch_reg(auprobe, regs);
autask = &current->utask->autask;
if (auprobe->fixups & UPROBE_FIX_RIP_AX)
regs->ax = autask->saved_scratch_register;
else
regs->cx = autask->saved_scratch_register;
/*
* The original instruction includes a displacement, and so
* is 4 bytes longer than what we've just single-stepped.
* Caller may need to apply other fixups to handle stuff
* like "jmpq *...(%rip)" and "callq *...(%rip)".
*/
if (correction)
*correction += 4;
*sr = utask->autask.saved_scratch_register;
}
}
static int validate_insn_64bits(struct arch_uprobe *auprobe, struct insn *insn)
{
insn_init(insn, auprobe->insn, true);
/* Skip good instruction prefixes; reject "bad" ones. */
insn_get_opcode(insn);
if (is_prefix_bad(insn))
return -ENOTSUPP;
if (test_bit(OPCODE1(insn), (unsigned long *)good_insns_64))
return 0;
if (insn->opcode.nbytes == 2) {
if (test_bit(OPCODE2(insn), (unsigned long *)good_2byte_insns))
return 0;
}
return -ENOTSUPP;
}
static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn)
{
if (mm->context.ia32_compat)
return validate_insn_32bits(auprobe, insn);
return validate_insn_64bits(auprobe, insn);
}
#else /* 32-bit: */
static inline bool is_64bit_mm(struct mm_struct *mm)
{
return false;
}
/*
* No RIP-relative addressing on 32-bit
*/
static void handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn)
static void riprel_analyze(struct arch_uprobe *auprobe, struct insn *insn)
{
}
static void pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
struct arch_uprobe_task *autask)
static void riprel_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
}
static void handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs,
long *correction)
static void riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
}
static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn)
{
return validate_insn_32bits(auprobe, insn);
}
#endif /* CONFIG_X86_64 */
struct uprobe_xol_ops {
bool (*emulate)(struct arch_uprobe *, struct pt_regs *);
int (*pre_xol)(struct arch_uprobe *, struct pt_regs *);
int (*post_xol)(struct arch_uprobe *, struct pt_regs *);
void (*abort)(struct arch_uprobe *, struct pt_regs *);
};
static inline int sizeof_long(void)
@ -415,50 +462,67 @@ static inline int sizeof_long(void)
static int default_pre_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
pre_xol_rip_insn(auprobe, regs, &current->utask->autask);
riprel_pre_xol(auprobe, regs);
return 0;
}
static int push_ret_address(struct pt_regs *regs, unsigned long ip)
{
unsigned long new_sp = regs->sp - sizeof_long();
if (copy_to_user((void __user *)new_sp, &ip, sizeof_long()))
return -EFAULT;
regs->sp = new_sp;
return 0;
}
/*
* Adjust the return address pushed by a call insn executed out of line.
* We have to fix things up as follows:
*
* Typically, the new ip is relative to the copied instruction. We need
* to make it relative to the original instruction (FIX_IP). Exceptions
* are return instructions and absolute or indirect jump or call instructions.
*
* If the single-stepped instruction was a call, the return address that
* is atop the stack is the address following the copied instruction. We
* need to make it the address following the original instruction (FIX_CALL).
*
* If the original instruction was a rip-relative instruction such as
* "movl %edx,0xnnnn(%rip)", we have instead executed an equivalent
* instruction using a scratch register -- e.g., "movl %edx,0xnnnn(%rsi)".
* We need to restore the contents of the scratch register
* (FIX_RIP_reg).
*/
static int adjust_ret_addr(unsigned long sp, long correction)
static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
int rasize = sizeof_long();
long ra;
struct uprobe_task *utask = current->utask;
if (copy_from_user(&ra, (void __user *)sp, rasize))
return -EFAULT;
ra += correction;
if (copy_to_user((void __user *)sp, &ra, rasize))
return -EFAULT;
riprel_post_xol(auprobe, regs);
if (auprobe->def.fixups & UPROBE_FIX_IP) {
long correction = utask->vaddr - utask->xol_vaddr;
regs->ip += correction;
} else if (auprobe->def.fixups & UPROBE_FIX_CALL) {
regs->sp += sizeof_long();
if (push_ret_address(regs, utask->vaddr + auprobe->def.ilen))
return -ERESTART;
}
/* popf; tell the caller to not touch TF */
if (auprobe->def.fixups & UPROBE_FIX_SETF)
utask->autask.saved_tf = true;
return 0;
}
static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
static void default_abort_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
long correction = (long)(utask->vaddr - utask->xol_vaddr);
handle_riprel_post_xol(auprobe, regs, &correction);
if (auprobe->fixups & UPROBE_FIX_IP)
regs->ip += correction;
if (auprobe->fixups & UPROBE_FIX_CALL) {
if (adjust_ret_addr(regs->sp, correction)) {
regs->sp += sizeof_long();
return -ERESTART;
}
}
return 0;
riprel_post_xol(auprobe, regs);
}
static struct uprobe_xol_ops default_xol_ops = {
.pre_xol = default_pre_xol_op,
.post_xol = default_post_xol_op,
.abort = default_abort_op,
};
static bool branch_is_call(struct arch_uprobe *auprobe)
@ -520,7 +584,6 @@ static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
unsigned long offs = (long)auprobe->branch.offs;
if (branch_is_call(auprobe)) {
unsigned long new_sp = regs->sp - sizeof_long();
/*
* If it fails we execute this (mangled, see the comment in
* branch_clear_offset) insn out-of-line. In the likely case
@ -530,9 +593,8 @@ static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
*
* But there is corner case, see the comment in ->post_xol().
*/
if (copy_to_user((void __user *)new_sp, &new_ip, sizeof_long()))
if (push_ret_address(regs, new_ip))
return false;
regs->sp = new_sp;
} else if (!check_jmp_cond(auprobe, regs)) {
offs = 0;
}
@ -583,11 +645,7 @@ static struct uprobe_xol_ops branch_xol_ops = {
static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
{
u8 opc1 = OPCODE1(insn);
/* has the side-effect of processing the entire instruction */
insn_get_length(insn);
if (WARN_ON_ONCE(!insn_complete(insn)))
return -ENOEXEC;
int i;
switch (opc1) {
case 0xeb: /* jmp 8 */
@ -612,6 +670,16 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
return -ENOSYS;
}
/*
* 16-bit overrides such as CALLW (66 e8 nn nn) are not supported.
* Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix.
* No one uses these insns, reject any branch insns with such prefix.
*/
for (i = 0; i < insn->prefixes.nbytes; i++) {
if (insn->prefixes.bytes[i] == 0x66)
return -ENOTSUPP;
}
auprobe->branch.opc1 = opc1;
auprobe->branch.ilen = insn->length;
auprobe->branch.offs = insn->immediate.value;
@ -630,10 +698,10 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long addr)
{
struct insn insn;
bool fix_ip = true, fix_call = false;
u8 fix_ip_or_call = UPROBE_FIX_IP;
int ret;
ret = validate_insn_bits(auprobe, mm, &insn);
ret = uprobe_init_insn(auprobe, &insn, is_64bit_mm(mm));
if (ret)
return ret;
@ -642,44 +710,40 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
return ret;
/*
* Figure out which fixups arch_uprobe_post_xol() will need to perform,
* and annotate arch_uprobe->fixups accordingly. To start with, ->fixups
* is either zero or it reflects rip-related fixups.
* Figure out which fixups default_post_xol_op() will need to perform,
* and annotate def->fixups accordingly. To start with, ->fixups is
* either zero or it reflects rip-related fixups.
*/
switch (OPCODE1(&insn)) {
case 0x9d: /* popf */
auprobe->fixups |= UPROBE_FIX_SETF;
auprobe->def.fixups |= UPROBE_FIX_SETF;
break;
case 0xc3: /* ret or lret -- ip is correct */
case 0xcb:
case 0xc2:
case 0xca:
fix_ip = false;
case 0xea: /* jmp absolute -- ip is correct */
fix_ip_or_call = 0;
break;
case 0x9a: /* call absolute - Fix return addr, not ip */
fix_call = true;
fix_ip = false;
break;
case 0xea: /* jmp absolute -- ip is correct */
fix_ip = false;
fix_ip_or_call = UPROBE_FIX_CALL;
break;
case 0xff:
insn_get_modrm(&insn);
switch (MODRM_REG(&insn)) {
case 2: case 3: /* call or lcall, indirect */
fix_call = true;
fix_ip_or_call = UPROBE_FIX_CALL;
break;
case 4: case 5: /* jmp or ljmp, indirect */
fix_ip = false;
fix_ip_or_call = 0;
break;
}
/* fall through */
default:
handle_riprel_insn(auprobe, &insn);
riprel_analyze(auprobe, &insn);
}
if (fix_ip)
auprobe->fixups |= UPROBE_FIX_IP;
if (fix_call)
auprobe->fixups |= UPROBE_FIX_CALL;
auprobe->def.ilen = insn.length;
auprobe->def.fixups |= fix_ip_or_call;
auprobe->ops = &default_xol_ops;
return 0;
@ -694,6 +758,12 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
if (auprobe->ops->pre_xol) {
int err = auprobe->ops->pre_xol(auprobe, regs);
if (err)
return err;
}
regs->ip = utask->xol_vaddr;
utask->autask.saved_trap_nr = current->thread.trap_nr;
current->thread.trap_nr = UPROBE_TRAP_NR;
@ -703,8 +773,6 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
if (test_tsk_thread_flag(current, TIF_BLOCKSTEP))
set_task_blockstep(current, false);
if (auprobe->ops->pre_xol)
return auprobe->ops->pre_xol(auprobe, regs);
return 0;
}
@ -732,56 +800,42 @@ bool arch_uprobe_xol_was_trapped(struct task_struct *t)
* single-step, we single-stepped a copy of the instruction.
*
* This function prepares to resume execution after the single-step.
* We have to fix things up as follows:
*
* Typically, the new ip is relative to the copied instruction. We need
* to make it relative to the original instruction (FIX_IP). Exceptions
* are return instructions and absolute or indirect jump or call instructions.
*
* If the single-stepped instruction was a call, the return address that
* is atop the stack is the address following the copied instruction. We
* need to make it the address following the original instruction (FIX_CALL).
*
* If the original instruction was a rip-relative instruction such as
* "movl %edx,0xnnnn(%rip)", we have instead executed an equivalent
* instruction using a scratch register -- e.g., "movl %edx,(%rax)".
* We need to restore the contents of the scratch register and adjust
* the ip, keeping in mind that the instruction we executed is 4 bytes
* shorter than the original instruction (since we squeezed out the offset
* field). (FIX_RIP_AX or FIX_RIP_CX)
*/
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
bool send_sigtrap = utask->autask.saved_tf;
int err = 0;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
current->thread.trap_nr = utask->autask.saved_trap_nr;
if (auprobe->ops->post_xol) {
int err = auprobe->ops->post_xol(auprobe, regs);
err = auprobe->ops->post_xol(auprobe, regs);
if (err) {
arch_uprobe_abort_xol(auprobe, regs);
/*
* Restart the probed insn. ->post_xol() must ensure
* this is really possible if it returns -ERESTART.
* Restore ->ip for restart or post mortem analysis.
* ->post_xol() must not return -ERESTART unless this
* is really possible.
*/
regs->ip = utask->vaddr;
if (err == -ERESTART)
return 0;
return err;
err = 0;
send_sigtrap = false;
}
}
current->thread.trap_nr = utask->autask.saved_trap_nr;
/*
* arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
* so we can get an extra SIGTRAP if we do not clear TF. We need
* to examine the opcode to make it right.
*/
if (utask->autask.saved_tf)
if (send_sigtrap)
send_sig(SIGTRAP, current, 0);
else if (!(auprobe->fixups & UPROBE_FIX_SETF))
if (!utask->autask.saved_tf)
regs->flags &= ~X86_EFLAGS_TF;
return 0;
return err;
}
/* callback routine for handling exceptions. */
@ -815,18 +869,18 @@ int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val,
/*
* This function gets called when XOL instruction either gets trapped or
* the thread has a fatal signal, or if arch_uprobe_post_xol() failed.
* Reset the instruction pointer to its probed address for the potential
* restart or for post mortem analysis.
* the thread has a fatal signal. Reset the instruction pointer to its
* probed address for the potential restart or for post mortem analysis.
*/
void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
current->thread.trap_nr = utask->autask.saved_trap_nr;
handle_riprel_post_xol(auprobe, regs, NULL);
instruction_pointer_set(regs, utask->vaddr);
if (auprobe->ops->abort)
auprobe->ops->abort(auprobe, regs);
current->thread.trap_nr = utask->autask.saved_trap_nr;
regs->ip = utask->vaddr;
/* clear TF if it was set by us in arch_uprobe_pre_xol() */
if (!utask->autask.saved_tf)
regs->flags &= ~X86_EFLAGS_TF;

4
include/linux/uprobes.h
View file

@ -102,6 +102,7 @@ extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, u
extern bool __weak is_swbp_insn(uprobe_opcode_t *insn);
extern bool __weak is_trap_insn(uprobe_opcode_t *insn);
extern unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs);
extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
extern int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t);
extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
extern int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool);
@ -130,6 +131,9 @@ extern bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *r
#else /* !CONFIG_UPROBES */
struct uprobes_state {
};
#define uprobe_get_trap_addr(regs) instruction_pointer(regs)
static inline int
uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
{

35
kernel/events/uprobes.c
View file

@ -127,7 +127,7 @@ struct xol_area {
*/
static bool valid_vma(struct vm_area_struct *vma, bool is_register)
{
vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED;
vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE;
if (is_register)
flags |= VM_WRITE;
@ -279,18 +279,13 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t
* supported by that architecture then we need to modify is_trap_at_addr and
* uprobe_write_opcode accordingly. This would never be a problem for archs
* that have fixed length instructions.
*/
/*
*
* uprobe_write_opcode - write the opcode at a given virtual address.
* @mm: the probed process address space.
* @vaddr: the virtual address to store the opcode.
* @opcode: opcode to be written at @vaddr.
*
* Called with mm->mmap_sem held (for read and with a reference to
* mm).
*
* For mm @mm, write the opcode at @vaddr.
* Called with mm->mmap_sem held for write.
* Return 0 (success) or a negative errno.
*/
int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
@ -310,21 +305,25 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
if (ret <= 0)
goto put_old;
ret = anon_vma_prepare(vma);
if (ret)
goto put_old;
ret = -ENOMEM;
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
if (!new_page)
goto put_old;
__SetPageUptodate(new_page);
if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))
goto put_new;
__SetPageUptodate(new_page);
copy_highpage(new_page, old_page);
copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
ret = anon_vma_prepare(vma);
if (ret)
goto put_new;
ret = __replace_page(vma, vaddr, old_page, new_page);
if (ret)
mem_cgroup_uncharge_page(new_page);
put_new:
page_cache_release(new_page);
@ -1352,6 +1351,16 @@ unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs)
return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE;
}
unsigned long uprobe_get_trap_addr(struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
if (unlikely(utask && utask->active_uprobe))
return utask->vaddr;
return instruction_pointer(regs);
}
/*
* Called with no locks held.
* Called in context of a exiting or a exec-ing thread.

54
kernel/trace/trace_uprobe.c
View file

@ -1009,9 +1009,32 @@ uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm);
}
static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
{
bool done;
write_lock(&tu->filter.rwlock);
if (event->hw.tp_target) {
list_del(&event->hw.tp_list);
done = tu->filter.nr_systemwide ||
(event->hw.tp_target->flags & PF_EXITING) ||
uprobe_filter_event(tu, event);
} else {
tu->filter.nr_systemwide--;
done = tu->filter.nr_systemwide;
}
write_unlock(&tu->filter.rwlock);
if (!done)
return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
return 0;
}
static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
{
bool done;
int err;
write_lock(&tu->filter.rwlock);
if (event->hw.tp_target) {
@ -1033,32 +1056,13 @@ static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
}
write_unlock(&tu->filter.rwlock);
if (!done)
uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
return 0;
}
static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
{
bool done;
write_lock(&tu->filter.rwlock);
if (event->hw.tp_target) {
list_del(&event->hw.tp_list);
done = tu->filter.nr_systemwide ||
(event->hw.tp_target->flags & PF_EXITING) ||
uprobe_filter_event(tu, event);
} else {
tu->filter.nr_systemwide--;
done = tu->filter.nr_systemwide;
err = 0;
if (!done) {
err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
if (err)
uprobe_perf_close(tu, event);
}
write_unlock(&tu->filter.rwlock);
if (!done)
uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
return 0;
return err;
}
static bool uprobe_perf_filter(struct uprobe_consumer *uc,