mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 00:50:50 +07:00
locking/refcount: Consolidate implementations of refcount_t
The generic implementation of refcount_t should be good enough for everybody, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely, leaving the generic implementation enabled unconditionally. Signed-off-by: Will Deacon <will@kernel.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Tested-by: Hanjun Guo <guohanjun@huawei.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Elena Reshetova <elena.reshetova@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20191121115902.2551-9-will@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Will Deacon
Ingo Molnar
parent
65b0085524
commit
fb041bb7c0
21
arch/Kconfig
21
arch/Kconfig
@ -892,27 +892,6 @@ config STRICT_MODULE_RWX
|
||||
config ARCH_HAS_PHYS_TO_DMA
|
||||
bool
|
||||
|
||||
config ARCH_HAS_REFCOUNT
|
||||
bool
|
||||
help
|
||||
An architecture selects this when it has implemented refcount_t
|
||||
using open coded assembly primitives that provide an optimized
|
||||
refcount_t implementation, possibly at the expense of some full
|
||||
refcount state checks of CONFIG_REFCOUNT_FULL=y.
|
||||
|
||||
The refcount overflow check behavior, however, must be retained.
|
||||
Catching overflows is the primary security concern for protecting
|
||||
against bugs in reference counts.
|
||||
|
||||
config REFCOUNT_FULL
|
||||
bool "Perform full reference count validation at the expense of speed"
|
||||
help
|
||||
Enabling this switches the refcounting infrastructure from a fast
|
||||
unchecked atomic_t implementation to a fully state checked
|
||||
implementation, which can be (slightly) slower but provides protections
|
||||
against various use-after-free conditions that can be used in
|
||||
security flaw exploits.
|
||||
|
||||
config HAVE_ARCH_COMPILER_H
|
||||
bool
|
||||
help
|
||||
|
||||
@ -117,7 +117,6 @@ config ARM
|
||||
select OLD_SIGSUSPEND3
|
||||
select PCI_SYSCALL if PCI
|
||||
select PERF_USE_VMALLOC
|
||||
select REFCOUNT_FULL
|
||||
select RTC_LIB
|
||||
select SYS_SUPPORTS_APM_EMULATION
|
||||
# Above selects are sorted alphabetically; please add new ones
|
||||
|
||||
@ -181,7 +181,6 @@ config ARM64
|
||||
select PCI_SYSCALL if PCI
|
||||
select POWER_RESET
|
||||
select POWER_SUPPLY
|
||||
select REFCOUNT_FULL
|
||||
select SPARSE_IRQ
|
||||
select SWIOTLB
|
||||
select SYSCTL_EXCEPTION_TRACE
|
||||
|
||||
@ -62,7 +62,6 @@ CONFIG_OPROFILE=m
|
||||
CONFIG_KPROBES=y
|
||||
CONFIG_JUMP_LABEL=y
|
||||
CONFIG_STATIC_KEYS_SELFTEST=y
|
||||
CONFIG_REFCOUNT_FULL=y
|
||||
CONFIG_LOCK_EVENT_COUNTS=y
|
||||
CONFIG_MODULES=y
|
||||
CONFIG_MODULE_FORCE_LOAD=y
|
||||
|
||||
@ -73,7 +73,6 @@ config X86
|
||||
select ARCH_HAS_PMEM_API if X86_64
|
||||
select ARCH_HAS_PTE_DEVMAP if X86_64
|
||||
select ARCH_HAS_PTE_SPECIAL
|
||||
select ARCH_HAS_REFCOUNT
|
||||
select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
|
||||
select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
|
||||
select ARCH_HAS_SET_MEMORY
|
||||
|
||||
@ -139,9 +139,6 @@
|
||||
# define _ASM_EXTABLE_EX(from, to) \
|
||||
_ASM_EXTABLE_HANDLE(from, to, ex_handler_ext)
|
||||
|
||||
# define _ASM_EXTABLE_REFCOUNT(from, to) \
|
||||
_ASM_EXTABLE_HANDLE(from, to, ex_handler_refcount)
|
||||
|
||||
# define _ASM_NOKPROBE(entry) \
|
||||
.pushsection "_kprobe_blacklist","aw" ; \
|
||||
_ASM_ALIGN ; \
|
||||
@ -170,9 +167,6 @@
|
||||
# define _ASM_EXTABLE_EX(from, to) \
|
||||
_ASM_EXTABLE_HANDLE(from, to, ex_handler_ext)
|
||||
|
||||
# define _ASM_EXTABLE_REFCOUNT(from, to) \
|
||||
_ASM_EXTABLE_HANDLE(from, to, ex_handler_refcount)
|
||||
|
||||
/* For C file, we already have NOKPROBE_SYMBOL macro */
|
||||
#endif
|
||||
|
||||
|
||||
@ -1,126 +0,0 @@
|
||||
#ifndef __ASM_X86_REFCOUNT_H
|
||||
#define __ASM_X86_REFCOUNT_H
|
||||
/*
|
||||
* x86-specific implementation of refcount_t. Based on PAX_REFCOUNT from
|
||||
* PaX/grsecurity.
|
||||
*/
|
||||
#include <linux/refcount.h>
|
||||
#include <asm/bug.h>
|
||||
|
||||
/*
|
||||
* This is the first portion of the refcount error handling, which lives in
|
||||
* .text.unlikely, and is jumped to from the CPU flag check (in the
|
||||
* following macros). This saves the refcount value location into CX for
|
||||
* the exception handler to use (in mm/extable.c), and then triggers the
|
||||
* central refcount exception. The fixup address for the exception points
|
||||
* back to the regular execution flow in .text.
|
||||
*/
|
||||
#define _REFCOUNT_EXCEPTION \
|
||||
".pushsection .text..refcount\n" \
|
||||
"111:\tlea %[var], %%" _ASM_CX "\n" \
|
||||
"112:\t" ASM_UD2 "\n" \
|
||||
ASM_UNREACHABLE \
|
||||
".popsection\n" \
|
||||
"113:\n" \
|
||||
_ASM_EXTABLE_REFCOUNT(112b, 113b)
|
||||
|
||||
/* Trigger refcount exception if refcount result is negative. */
|
||||
#define REFCOUNT_CHECK_LT_ZERO \
|
||||
"js 111f\n\t" \
|
||||
_REFCOUNT_EXCEPTION
|
||||
|
||||
/* Trigger refcount exception if refcount result is zero or negative. */
|
||||
#define REFCOUNT_CHECK_LE_ZERO \
|
||||
"jz 111f\n\t" \
|
||||
REFCOUNT_CHECK_LT_ZERO
|
||||
|
||||
/* Trigger refcount exception unconditionally. */
|
||||
#define REFCOUNT_ERROR \
|
||||
"jmp 111f\n\t" \
|
||||
_REFCOUNT_EXCEPTION
|
||||
|
||||
static __always_inline void refcount_add(unsigned int i, refcount_t *r)
|
||||
{
|
||||
asm volatile(LOCK_PREFIX "addl %1,%0\n\t"
|
||||
REFCOUNT_CHECK_LT_ZERO
|
||||
: [var] "+m" (r->refs.counter)
|
||||
: "ir" (i)
|
||||
: "cc", "cx");
|
||||
}
|
||||
|
||||
static __always_inline void refcount_inc(refcount_t *r)
|
||||
{
|
||||
asm volatile(LOCK_PREFIX "incl %0\n\t"
|
||||
REFCOUNT_CHECK_LT_ZERO
|
||||
: [var] "+m" (r->refs.counter)
|
||||
: : "cc", "cx");
|
||||
}
|
||||
|
||||
static __always_inline void refcount_dec(refcount_t *r)
|
||||
{
|
||||
asm volatile(LOCK_PREFIX "decl %0\n\t"
|
||||
REFCOUNT_CHECK_LE_ZERO
|
||||
: [var] "+m" (r->refs.counter)
|
||||
: : "cc", "cx");
|
||||
}
|
||||
|
||||
static __always_inline __must_check
|
||||
bool refcount_sub_and_test(unsigned int i, refcount_t *r)
|
||||
{
|
||||
bool ret = GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl",
|
||||
REFCOUNT_CHECK_LT_ZERO,
|
||||
r->refs.counter, e, "er", i, "cx");
|
||||
|
||||
if (ret) {
|
||||
smp_acquire__after_ctrl_dep();
|
||||
return true;
|
||||
}
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
static __always_inline __must_check bool refcount_dec_and_test(refcount_t *r)
|
||||
{
|
||||
bool ret = GEN_UNARY_SUFFIXED_RMWcc(LOCK_PREFIX "decl",
|
||||
REFCOUNT_CHECK_LT_ZERO,
|
||||
r->refs.counter, e, "cx");
|
||||
|
||||
if (ret) {
|
||||
smp_acquire__after_ctrl_dep();
|
||||
return true;
|
||||
}
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
static __always_inline __must_check
|
||||
bool refcount_add_not_zero(unsigned int i, refcount_t *r)
|
||||
{
|
||||
int c, result;
|
||||
|
||||
c = atomic_read(&(r->refs));
|
||||
do {
|
||||
if (unlikely(c == 0))
|
||||
return false;
|
||||
|
||||
result = c + i;
|
||||
|
||||
/* Did we try to increment from/to an undesirable state? */
|
||||
if (unlikely(c < 0 || c == INT_MAX || result < c)) {
|
||||
asm volatile(REFCOUNT_ERROR
|
||||
: : [var] "m" (r->refs.counter)
|
||||
: "cc", "cx");
|
||||
break;
|
||||
}
|
||||
|
||||
} while (!atomic_try_cmpxchg(&(r->refs), &c, result));
|
||||
|
||||
return c != 0;
|
||||
}
|
||||
|
||||
static __always_inline __must_check bool refcount_inc_not_zero(refcount_t *r)
|
||||
{
|
||||
return refcount_add_not_zero(1, r);
|
||||
}
|
||||
|
||||
#endif
|
||||
@ -44,55 +44,6 @@ __visible bool ex_handler_fault(const struct exception_table_entry *fixup,
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(ex_handler_fault);
|
||||
|
||||
/*
|
||||
* Handler for UD0 exception following a failed test against the
|
||||
* result of a refcount inc/dec/add/sub.
|
||||
*/
|
||||
__visible bool ex_handler_refcount(const struct exception_table_entry *fixup,
|
||||
struct pt_regs *regs, int trapnr,
|
||||
unsigned long error_code,
|
||||
unsigned long fault_addr)
|
||||
{
|
||||
/* First unconditionally saturate the refcount. */
|
||||
*(int *)regs->cx = INT_MIN / 2;
|
||||
|
||||
/*
|
||||
* Strictly speaking, this reports the fixup destination, not
|
||||
* the fault location, and not the actually overflowing
|
||||
* instruction, which is the instruction before the "js", but
|
||||
* since that instruction could be a variety of lengths, just
|
||||
* report the location after the overflow, which should be close
|
||||
* enough for finding the overflow, as it's at least back in
|
||||
* the function, having returned from .text.unlikely.
|
||||
*/
|
||||
regs->ip = ex_fixup_addr(fixup);
|
||||
|
||||
/*
|
||||
* This function has been called because either a negative refcount
|
||||
* value was seen by any of the refcount functions, or a zero
|
||||
* refcount value was seen by refcount_dec().
|
||||
*
|
||||
* If we crossed from INT_MAX to INT_MIN, OF (Overflow Flag: result
|
||||
* wrapped around) will be set. Additionally, seeing the refcount
|
||||
* reach 0 will set ZF (Zero Flag: result was zero). In each of
|
||||
* these cases we want a report, since it's a boundary condition.
|
||||
* The SF case is not reported since it indicates post-boundary
|
||||
* manipulations below zero or above INT_MAX. And if none of the
|
||||
* flags are set, something has gone very wrong, so report it.
|
||||
*/
|
||||
if (regs->flags & (X86_EFLAGS_OF | X86_EFLAGS_ZF)) {
|
||||
bool zero = regs->flags & X86_EFLAGS_ZF;
|
||||
|
||||
refcount_error_report(regs, zero ? "hit zero" : "overflow");
|
||||
} else if ((regs->flags & X86_EFLAGS_SF) == 0) {
|
||||
/* Report if none of OF, ZF, nor SF are set. */
|
||||
refcount_error_report(regs, "unexpected saturation");
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
EXPORT_SYMBOL(ex_handler_refcount);
|
||||
|
||||
/*
|
||||
* Handler for when we fail to restore a task's FPU state. We should never get
|
||||
* here because the FPU state of a task using the FPU (task->thread.fpu.state)
|
||||
|
||||
@ -22,7 +22,6 @@ config DRM_I915_DEBUG
|
||||
depends on DRM_I915
|
||||
select DEBUG_FS
|
||||
select PREEMPT_COUNT
|
||||
select REFCOUNT_FULL
|
||||
select I2C_CHARDEV
|
||||
select STACKDEPOT
|
||||
select DRM_DP_AUX_CHARDEV
|
||||
|
||||
@ -1,64 +1,4 @@
|
||||
/* SPDX-License-Identifier: GPL-2.0 */
|
||||
#ifndef _LINUX_REFCOUNT_H
|
||||
#define _LINUX_REFCOUNT_H
|
||||
|
||||
#include <linux/atomic.h>
|
||||
#include <linux/compiler.h>
|
||||
#include <linux/limits.h>
|
||||
#include <linux/spinlock_types.h>
|
||||
|
||||
struct mutex;
|
||||
|
||||
/**
|
||||
* struct refcount_t - variant of atomic_t specialized for reference counts
|
||||
* @refs: atomic_t counter field
|
||||
*
|
||||
* The counter saturates at REFCOUNT_SATURATED and will not move once
|
||||
* there. This avoids wrapping the counter and causing 'spurious'
|
||||
* use-after-free bugs.
|
||||
*/
|
||||
typedef struct refcount_struct {
|
||||
atomic_t refs;
|
||||
} refcount_t;
|
||||
|
||||
#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
|
||||
#define REFCOUNT_MAX INT_MAX
|
||||
#define REFCOUNT_SATURATED (INT_MIN / 2)
|
||||
|
||||
enum refcount_saturation_type {
|
||||
REFCOUNT_ADD_NOT_ZERO_OVF,
|
||||
REFCOUNT_ADD_OVF,
|
||||
REFCOUNT_ADD_UAF,
|
||||
REFCOUNT_SUB_UAF,
|
||||
REFCOUNT_DEC_LEAK,
|
||||
};
|
||||
|
||||
void refcount_warn_saturate(refcount_t *r, enum refcount_saturation_type t);
|
||||
|
||||
/**
|
||||
* refcount_set - set a refcount's value
|
||||
* @r: the refcount
|
||||
* @n: value to which the refcount will be set
|
||||
*/
|
||||
static inline void refcount_set(refcount_t *r, int n)
|
||||
{
|
||||
atomic_set(&r->refs, n);
|
||||
}
|
||||
|
||||
/**
|
||||
* refcount_read - get a refcount's value
|
||||
* @r: the refcount
|
||||
*
|
||||
* Return: the refcount's value
|
||||
*/
|
||||
static inline unsigned int refcount_read(const refcount_t *r)
|
||||
{
|
||||
return atomic_read(&r->refs);
|
||||
}
|
||||
|
||||
#ifdef CONFIG_REFCOUNT_FULL
|
||||
#include <linux/bug.h>
|
||||
|
||||
/*
|
||||
* Variant of atomic_t specialized for reference counts.
|
||||
*
|
||||
@ -136,6 +76,64 @@ static inline unsigned int refcount_read(const refcount_t *r)
|
||||
*
|
||||
*/
|
||||
|
||||
#ifndef _LINUX_REFCOUNT_H
|
||||
#define _LINUX_REFCOUNT_H
|
||||
|
||||
#include <linux/atomic.h>
|
||||
#include <linux/bug.h>
|
||||
#include <linux/compiler.h>
|
||||
#include <linux/limits.h>
|
||||
#include <linux/spinlock_types.h>
|
||||
|
||||
struct mutex;
|
||||
|
||||
/**
|
||||
* struct refcount_t - variant of atomic_t specialized for reference counts
|
||||
* @refs: atomic_t counter field
|
||||
*
|
||||
* The counter saturates at REFCOUNT_SATURATED and will not move once
|
||||
* there. This avoids wrapping the counter and causing 'spurious'
|
||||
* use-after-free bugs.
|
||||
*/
|
||||
typedef struct refcount_struct {
|
||||
atomic_t refs;
|
||||
} refcount_t;
|
||||
|
||||
#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
|
||||
#define REFCOUNT_MAX INT_MAX
|
||||
#define REFCOUNT_SATURATED (INT_MIN / 2)
|
||||
|
||||
enum refcount_saturation_type {
|
||||
REFCOUNT_ADD_NOT_ZERO_OVF,
|
||||
REFCOUNT_ADD_OVF,
|
||||
REFCOUNT_ADD_UAF,
|
||||
REFCOUNT_SUB_UAF,
|
||||
REFCOUNT_DEC_LEAK,
|
||||
};
|
||||
|
||||
void refcount_warn_saturate(refcount_t *r, enum refcount_saturation_type t);
|
||||
|
||||
/**
|
||||
* refcount_set - set a refcount's value
|
||||
* @r: the refcount
|
||||
* @n: value to which the refcount will be set
|
||||
*/
|
||||
static inline void refcount_set(refcount_t *r, int n)
|
||||
{
|
||||
atomic_set(&r->refs, n);
|
||||
}
|
||||
|
||||
/**
|
||||
* refcount_read - get a refcount's value
|
||||
* @r: the refcount
|
||||
*
|
||||
* Return: the refcount's value
|
||||
*/
|
||||
static inline unsigned int refcount_read(const refcount_t *r)
|
||||
{
|
||||
return atomic_read(&r->refs);
|
||||
}
|
||||
|
||||
/**
|
||||
* refcount_add_not_zero - add a value to a refcount unless it is 0
|
||||
* @i: the value to add to the refcount
|
||||
@ -298,46 +296,6 @@ static inline void refcount_dec(refcount_t *r)
|
||||
if (unlikely(atomic_fetch_sub_release(1, &r->refs) <= 1))
|
||||
refcount_warn_saturate(r, REFCOUNT_DEC_LEAK);
|
||||
}
|
||||
#else /* CONFIG_REFCOUNT_FULL */
|
||||
# ifdef CONFIG_ARCH_HAS_REFCOUNT
|
||||
# include <asm/refcount.h>
|
||||
# else
|
||||
static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r)
|
||||
{
|
||||
return atomic_add_unless(&r->refs, i, 0);
|
||||
}
|
||||
|
||||
static inline void refcount_add(int i, refcount_t *r)
|
||||
{
|
||||
atomic_add(i, &r->refs);
|
||||
}
|
||||
|
||||
static inline __must_check bool refcount_inc_not_zero(refcount_t *r)
|
||||
{
|
||||
return atomic_add_unless(&r->refs, 1, 0);
|
||||
}
|
||||
|
||||
static inline void refcount_inc(refcount_t *r)
|
||||
{
|
||||
atomic_inc(&r->refs);
|
||||
}
|
||||
|
||||
static inline __must_check bool refcount_sub_and_test(int i, refcount_t *r)
|
||||
{
|
||||
return atomic_sub_and_test(i, &r->refs);
|
||||
}
|
||||
|
||||
static inline __must_check bool refcount_dec_and_test(refcount_t *r)
|
||||
{
|
||||
return atomic_dec_and_test(&r->refs);
|
||||
}
|
||||
|
||||
static inline void refcount_dec(refcount_t *r)
|
||||
{
|
||||
atomic_dec(&r->refs);
|
||||
}
|
||||
# endif /* !CONFIG_ARCH_HAS_REFCOUNT */
|
||||
#endif /* !CONFIG_REFCOUNT_FULL */
|
||||
|
||||
extern __must_check bool refcount_dec_if_one(refcount_t *r);
|
||||
extern __must_check bool refcount_dec_not_one(refcount_t *r);
|
||||
|
||||
@ -1,6 +1,6 @@
|
||||
// SPDX-License-Identifier: GPL-2.0
|
||||
/*
|
||||
* Out-of-line refcount functions common to all refcount implementations.
|
||||
* Out-of-line refcount functions.
|
||||
*/
|
||||
|
||||
#include <linux/mutex.h>
|
||||
|
||||
Loading…
Reference in New Issue
Block a user