[tip: x86/iopl] x86/ioperm: Move iobitmap data into a struct

From: tip-bot2 for Thomas Gleixner
Date: Fri Nov 15 2019 - 16:13:25 EST

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The following commit has been merged into the x86/iopl branch of tip:

Commit-ID: a975eef7788ec94ee548a4f182592b425759b7db
Gitweb: https://git.kernel.org/tip/a975eef7788ec94ee548a4f182592b425759b7db
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Wed, 13 Nov 2019 21:42:50 +01:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 14 Nov 2019 20:15:03 +01:00

x86/ioperm: Move iobitmap data into a struct

No point in having all the data in thread_struct, especially as upcoming
changes add more.

Make the bitmap in the new struct accessible as array of longs and as array
of characters via a union, so both the bitmap functions and the update
logic can avoid type casts.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20191113210104.683535229@xxxxxxxxxxxxx

---
arch/x86/include/asm/io_bitmap.h | 13 +++++++++++-
arch/x86/include/asm/processor.h | 6 +----
arch/x86/kernel/ioport.c | 27 +++++++++++-----------
arch/x86/kernel/process.c | 38 ++++++++++++++++---------------
arch/x86/kernel/ptrace.c | 12 ++++++----
5 files changed, 57 insertions(+), 39 deletions(-)
create mode 100644 arch/x86/include/asm/io_bitmap.h

diff --git a/arch/x86/include/asm/io_bitmap.h b/arch/x86/include/asm/io_bitmap.h
new file mode 100644
index 0000000..1a12b9f
--- /dev/null
+++ b/arch/x86/include/asm/io_bitmap.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_IOBITMAP_H
+#define _ASM_X86_IOBITMAP_H
+
+#include <asm/processor.h>
+
+struct io_bitmap {
+ /* The maximum number of bytes to copy so all zero bits are covered */
+ unsigned int max;
+ unsigned long bitmap[IO_BITMAP_LONGS];
+};
+
+#endif
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index cd7cd7d..c949e0e 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -7,6 +7,7 @@
/* Forward declaration, a strange C thing */
struct task_struct;
struct mm_struct;
+struct io_bitmap;
struct vm86;

#include <asm/math_emu.h>
@@ -501,10 +502,8 @@ struct thread_struct {
struct vm86 *vm86;
#endif
/* IO permissions: */
- unsigned long *io_bitmap_ptr;
+ struct io_bitmap *io_bitmap;
unsigned long iopl;
- /* Max allowed port in the bitmap, in bytes: */
- unsigned io_bitmap_max;

mm_segment_t addr_limit;

@@ -862,7 +861,6 @@ static inline void spin_lock_prefetch(const void *x)
#define INIT_THREAD { \
.sp0 = TOP_OF_INIT_STACK, \
.sysenter_cs = __KERNEL_CS, \
- .io_bitmap_ptr = NULL, \
.addr_limit = KERNEL_DS, \
}

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 80d99bb..05f77f3 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -11,6 +11,7 @@
#include <linux/sched.h>
#include <linux/slab.h>

+#include <asm/io_bitmap.h>
#include <asm/desc.h>

/*
@@ -21,7 +22,7 @@ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
unsigned int i, max_long, bytes, bytes_updated;
struct thread_struct *t = &current->thread;
struct tss_struct *tss;
- unsigned long *bitmap;
+ struct io_bitmap *iobm;

if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
return -EINVAL;
@@ -34,16 +35,16 @@ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
* IO bitmap up. ioperm() is much less timing critical than clone(),
* this is why we delay this operation until now:
*/
- bitmap = t->io_bitmap_ptr;
- if (!bitmap) {
+ iobm = t->io_bitmap;
+ if (!iobm) {
/* No point to allocate a bitmap just to clear permissions */
if (!turn_on)
return 0;
- bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
- if (!bitmap)
+ iobm = kmalloc(sizeof(*iobm), GFP_KERNEL);
+ if (!iobm)
return -ENOMEM;

- memset(bitmap, 0xff, IO_BITMAP_BYTES);
+ memset(iobm->bitmap, 0xff, sizeof(iobm->bitmap));
}

/*
@@ -52,9 +53,9 @@ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
*/
preempt_disable();
if (turn_on)
- bitmap_clear(bitmap, from, num);
+ bitmap_clear(iobm->bitmap, from, num);
else
- bitmap_set(bitmap, from, num);
+ bitmap_set(iobm->bitmap, from, num);

/*
* Search for a (possibly new) maximum. This is simple and stupid,
@@ -62,26 +63,26 @@ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
*/
max_long = 0;
for (i = 0; i < IO_BITMAP_LONGS; i++) {
- if (bitmap[i] != ~0UL)
+ if (iobm->bitmap[i] != ~0UL)
max_long = i;
}

bytes = (max_long + 1) * sizeof(unsigned long);
- bytes_updated = max(bytes, t->io_bitmap_max);
+ bytes_updated = max(bytes, t->io_bitmap->max);

/* Update the thread data */
- t->io_bitmap_max = bytes;
+ iobm->max = bytes;
/*
* Store the bitmap pointer (might be the same if the task already
* head one). Set the TIF flag, just in case this is the first
* invocation.
*/
- t->io_bitmap_ptr = bitmap;
+ t->io_bitmap = iobm;
set_thread_flag(TIF_IO_BITMAP);

/* Update the TSS */
tss = this_cpu_ptr(&cpu_tss_rw);
- memcpy(tss->io_bitmap.bitmap, t->io_bitmap_ptr, bytes_updated);
+ memcpy(tss->io_bitmap.bitmap, iobm->bitmap, bytes_updated);
/* Store the new end of the zero bits */
tss->io_bitmap.prev_max = bytes;
/* Make the bitmap base in the TSS valid */
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 3e2f1aa..39c495d 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -41,6 +41,7 @@
#include <asm/desc.h>
#include <asm/prctl.h>
#include <asm/spec-ctrl.h>
+#include <asm/io_bitmap.h>
#include <asm/proto.h>

#include "process.h"
@@ -101,21 +102,20 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
void exit_thread(struct task_struct *tsk)
{
struct thread_struct *t = &tsk->thread;
- unsigned long *bp = t->io_bitmap_ptr;
+ struct io_bitmap *iobm = t->io_bitmap;
struct fpu *fpu = &t->fpu;
struct tss_struct *tss;

- if (bp) {
+ if (iobm) {
preempt_disable();
tss = this_cpu_ptr(&cpu_tss_rw);

- t->io_bitmap_ptr = NULL;
- t->io_bitmap_max = 0;
+ t->io_bitmap = NULL;
clear_thread_flag(TIF_IO_BITMAP);
/* Invalidate the io bitmap base in the TSS */
tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET_INVALID;
preempt_enable();
- kfree(bp);
+ kfree(iobm);
}

free_vm86(t);
@@ -135,25 +135,25 @@ static int set_new_tls(struct task_struct *p, unsigned long tls)

static inline int copy_io_bitmap(struct task_struct *tsk)
{
+ struct io_bitmap *iobm = current->thread.io_bitmap;
+
if (likely(!test_tsk_thread_flag(current, TIF_IO_BITMAP)))
return 0;

- tsk->thread.io_bitmap_ptr = kmemdup(current->thread.io_bitmap_ptr,
- IO_BITMAP_BYTES, GFP_KERNEL);
- if (!tsk->thread.io_bitmap_ptr) {
- tsk->thread.io_bitmap_max = 0;
+ tsk->thread.io_bitmap = kmemdup(iobm, sizeof(*iobm), GFP_KERNEL);
+
+ if (!tsk->thread.io_bitmap)
return -ENOMEM;
- }
+
set_tsk_thread_flag(tsk, TIF_IO_BITMAP);
return 0;
}

static inline void free_io_bitmap(struct task_struct *tsk)
{
- if (tsk->thread.io_bitmap_ptr) {
- kfree(tsk->thread.io_bitmap_ptr);
- tsk->thread.io_bitmap_ptr = NULL;
- tsk->thread.io_bitmap_max = 0;
+ if (tsk->thread.io_bitmap) {
+ kfree(tsk->thread.io_bitmap);
+ tsk->thread.io_bitmap = NULL;
}
}

@@ -172,7 +172,7 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
frame->bp = 0;
frame->ret_addr = (unsigned long) ret_from_fork;
p->thread.sp = (unsigned long) fork_frame;
- p->thread.io_bitmap_ptr = NULL;
+ p->thread.io_bitmap = NULL;
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));

#ifdef CONFIG_X86_64
@@ -360,6 +360,8 @@ static inline void switch_to_bitmap(struct thread_struct *next,
struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw);

if (tifn & _TIF_IO_BITMAP) {
+ struct io_bitmap *iobm = next->io_bitmap;
+
/*
* Copy at least the size of the incoming tasks bitmap
* which covers the last permitted I/O port.
@@ -368,11 +370,11 @@ static inline void switch_to_bitmap(struct thread_struct *next,
* bits permitted, then the copy needs to cover those as
* well so they get turned off.
*/
- memcpy(tss->io_bitmap.bitmap, next->io_bitmap_ptr,
- max(tss->io_bitmap.prev_max, next->io_bitmap_max));
+ memcpy(tss->io_bitmap.bitmap, next->io_bitmap->bitmap,
+ max(tss->io_bitmap.prev_max, next->io_bitmap->max));

/* Store the new max and set io_bitmap_base valid */
- tss->io_bitmap.prev_max = next->io_bitmap_max;
+ tss->io_bitmap.prev_max = next->io_bitmap->max;
tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET_VALID;

/*
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7c52674..066e5b0 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -42,6 +42,7 @@
#include <asm/traps.h>
#include <asm/syscall.h>
#include <asm/fsgsbase.h>
+#include <asm/io_bitmap.h>

#include "tls.h"

@@ -697,7 +698,9 @@ static int ptrace_set_debugreg(struct task_struct *tsk, int n,
static int ioperm_active(struct task_struct *target,
const struct user_regset *regset)
{
- return DIV_ROUND_UP(target->thread.io_bitmap_max, regset->size);
+ struct io_bitmap *iobm = target->thread.io_bitmap;
+
+ return iobm ? DIV_ROUND_UP(iobm->max, regset->size) : 0;
}

static int ioperm_get(struct task_struct *target,
@@ -705,12 +708,13 @@ static int ioperm_get(struct task_struct *target,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
- if (!target->thread.io_bitmap_ptr)
+ struct io_bitmap *iobm = target->thread.io_bitmap;
+
+ if (!iobm)
return -ENXIO;

return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
- target->thread.io_bitmap_ptr,
- 0, IO_BITMAP_BYTES);
+ iobm->bitmap, 0, IO_BITMAP_BYTES);
}

/*

Next message: Joe Perches: "Re: [PATCH] iommu/iova: silence warnings under memory pressure"
Previous message: tip-bot2 for Thomas Gleixner: "[tip: x86/iopl] x86/ptrace: Prevent truncation of bitmap size"
In reply to: Thomas Gleixner: "[patch V3 10/20] x86/ioperm: Move iobitmap data into a struct"
Next in thread: Thomas Gleixner: "[patch V3 13/20] x86/ioperm: Remove bitmap if all permissions dropped"
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