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um: Rework syscall handling

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Rework syscall handling to be platform independent. Also create a clean
split between queueing of syscalls and flushing them out, removing the
need to keep state in the code that triggers the syscalls.

The code adds syscall_data_len to the global mm_id structure. This will
be used later to allow surrounding code to track whether syscalls still
need to run and if errors occurred.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Link: https://patch.msgid.link/20240703134536.1161108-5-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Benjamin Berg 2024-07-03 15:45:28 +02:00 committed by Johannes Berg
parent 542dc79f6e
commit 76ed9158e1
16 changed files with 271 additions and 294 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
arch/um/include/shared/os.h
View File

@ -272,19 +272,15 @@ extern long long os_persistent_clock_emulation(void);
extern long long os_nsecs(void);
/* skas/mem.c */
extern long run_syscall_stub(struct mm_id * mm_idp,
int syscall, unsigned long *args, long expected,
void **addr, int done);
extern long syscall_stub_data(struct mm_id * mm_idp,
unsigned long *data, int data_count,
void **addr, void **stub_addr);
extern int map(struct mm_id * mm_idp, unsigned long virt,
unsigned long len, int prot, int phys_fd,
unsigned long long offset, int done, void **data);
extern int unmap(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
int done, void **data);
extern int protect(struct mm_id * mm_idp, unsigned long addr,
unsigned long len, unsigned int prot, int done, void **data);
int syscall_stub_flush(struct mm_id *mm_idp);
struct stub_syscall *syscall_stub_alloc(struct mm_id *mm_idp);
void map(struct mm_id *mm_idp, unsigned long virt,
unsigned long len, int prot, int phys_fd,
unsigned long long offset);
void unmap(struct mm_id *mm_idp, unsigned long addr, unsigned long len);
void protect(struct mm_id *mm_idp, unsigned long addr,
unsigned long len, unsigned int prot);
/* skas/process.c */
extern int is_skas_winch(int pid, int fd, void *data);

1
arch/um/include/shared/skas/mm_id.h
View File

@ -13,6 +13,7 @@ struct mm_id {
} u;
unsigned long stack;
int kill;
int syscall_data_len;
};
void __switch_mm(struct mm_id *mm_idp);

35
arch/um/include/shared/skas/stub-data.h
View File

@ -10,14 +10,45 @@
#include <linux/compiler_types.h>
#include <as-layout.h>
#include <sysdep/tls.h>
#define STUB_NEXT_SYSCALL(s) \
((struct stub_syscall *) (((unsigned long) s) + (s)->cmd_len))
enum stub_syscall_type {
STUB_SYSCALL_UNSET = 0,
STUB_SYSCALL_MMAP,
STUB_SYSCALL_MUNMAP,
STUB_SYSCALL_MPROTECT,
STUB_SYSCALL_LDT,
};
struct stub_syscall {
union {
struct {
unsigned long addr;
unsigned long length;
unsigned long offset;
int fd;
int prot;
} mem;
struct {
user_desc_t desc;
int func;
} ldt;
};
enum stub_syscall_type syscall;
};
struct stub_data {
unsigned long offset;
int fd;
long parent_err, child_err;
long err, child_err;
int syscall_data_len;
/* 128 leaves enough room for additional fields in the struct */
unsigned char syscall_data[UM_KERN_PAGE_SIZE - 128] __aligned(16);
struct stub_syscall syscall_data[(UM_KERN_PAGE_SIZE - 128) / sizeof(struct stub_syscall)] __aligned(16);
/* Stack for our signal handlers and for calling into . */
unsigned char sigstack[UM_KERN_PAGE_SIZE] __aligned(UM_KERN_PAGE_SIZE);

8
arch/um/include/shared/user.h
View File

@ -42,11 +42,19 @@ extern void panic(const char *fmt, ...)
#define printk(...) _printk(__VA_ARGS__)
extern int _printk(const char *fmt, ...)
__attribute__ ((format (printf, 1, 2)));
extern void print_hex_dump(const char *level, const char *prefix_str,
int prefix_type, int rowsize, int groupsize,
const void *buf, size_t len, _Bool ascii);
#else
static inline int printk(const char *fmt, ...)
{
return 0;
}
static inline void print_hex_dump(const char *level, const char *prefix_str,
int prefix_type, int rowsize, int groupsize,
const void *buf, size_t len, _Bool ascii)
{
}
#endif
extern int in_aton(char *str);

10
arch/um/kernel/exec.c
View File

@ -22,15 +22,11 @@
void flush_thread(void)
{
void *data = NULL;
int ret;
arch_flush_thread(&current->thread.arch);
ret = unmap(&current->mm->context.id, 0, TASK_SIZE, 1, &data);
if (ret) {
printk(KERN_ERR "%s - clearing address space failed, err = %d\n",
__func__, ret);
unmap(&current->mm->context.id, 0, TASK_SIZE);
if (syscall_stub_flush(&current->mm->context.id) < 0) {
printk(KERN_ERR "%s - clearing address space failed", __func__);
force_sig(SIGKILL);
}
get_safe_registers(current_pt_regs()->regs.gp,

7
arch/um/kernel/skas/Makefile
View File

@ -3,14 +3,15 @@
# Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
#
obj-y := clone.o mmu.o process.o syscall.o uaccess.o
obj-y := clone.o stub.o mmu.o process.o syscall.o uaccess.o
# clone.o is in the stub, so it can't be built with profiling
# clone.o and stub.o are in the stub, so it can't be built with profiling
# GCC hardened also auto-enables -fpic, but we need %ebx so it can't work ->
# disable it
CFLAGS_clone.o := $(CFLAGS_NO_HARDENING)
UNPROFILE_OBJS := clone.o
CFLAGS_stub.o := $(CFLAGS_NO_HARDENING)
UNPROFILE_OBJS := clone.o stub.o
KCOV_INSTRUMENT := n

2
arch/um/kernel/skas/clone.c
View File

@ -33,7 +33,7 @@ stub_clone_handler(void)
sizeof(data->syscall_data) / 2 -
sizeof(void *));
if (err) {
data->parent_err = err;
data->err = err;
goto done;
}

80
arch/um/kernel/skas/stub.c Normal file
View File

@ -0,0 +1,80 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2021 Benjamin Berg <benjamin@sipsolutions.net>
*/
#include <sysdep/stub.h>
static __always_inline int syscall_handler(struct stub_data *d)
{
int i;
unsigned long res;
for (i = 0; i < d->syscall_data_len; i++) {
struct stub_syscall *sc = &d->syscall_data[i];
switch (sc->syscall) {
case STUB_SYSCALL_MMAP:
res = stub_syscall6(STUB_MMAP_NR,
sc->mem.addr, sc->mem.length,
sc->mem.prot,
MAP_SHARED | MAP_FIXED,
sc->mem.fd, sc->mem.offset);
if (res != sc->mem.addr) {
d->err = res;
d->syscall_data_len = i;
return -1;
}
break;
case STUB_SYSCALL_MUNMAP:
res = stub_syscall2(__NR_munmap,
sc->mem.addr, sc->mem.length);
if (res) {
d->err = res;
d->syscall_data_len = i;
return -1;
}
break;
case STUB_SYSCALL_MPROTECT:
res = stub_syscall3(__NR_mprotect,
sc->mem.addr, sc->mem.length,
sc->mem.prot);
if (res) {
d->err = res;
d->syscall_data_len = i;
return -1;
}
break;
case STUB_SYSCALL_LDT:
res = stub_syscall3(__NR_modify_ldt, sc->ldt.func,
(unsigned long) &sc->ldt.desc,
sizeof(sc->ldt.desc));
/* We only write, so the expected result is zero */
if (res) {
d->err = res;
d->syscall_data_len = i;
return -1;
}
break;
default:
d->err = -95; /* EOPNOTSUPP */
d->syscall_data_len = i;
return -1;
}
}
d->err = 0;
d->syscall_data_len = 0;
return 0;
}
void __section(".__syscall_stub")
stub_syscall_handler(void)
{
struct stub_data *d = get_stub_data();
syscall_handler(d);
trap_myself();
}

42
arch/um/kernel/tlb.c
View File

@ -71,21 +71,19 @@ static int do_ops(struct host_vm_change *hvc, int end,
switch (op->type) {
case MMAP:
if (hvc->userspace)
ret = map(&hvc->mm->context.id, op->u.mmap.addr,
op->u.mmap.len, op->u.mmap.prot,
op->u.mmap.fd,
op->u.mmap.offset, finished,
&hvc->data);
map(&hvc->mm->context.id, op->u.mmap.addr,
op->u.mmap.len, op->u.mmap.prot,
op->u.mmap.fd,
op->u.mmap.offset);
else
map_memory(op->u.mmap.addr, op->u.mmap.offset,
op->u.mmap.len, 1, 1, 1);
break;
case MUNMAP:
if (hvc->userspace)
ret = unmap(&hvc->mm->context.id,
op->u.munmap.addr,
op->u.munmap.len, finished,
&hvc->data);
unmap(&hvc->mm->context.id,
op->u.munmap.addr,
op->u.munmap.len);
else
ret = os_unmap_memory(
(void *) op->u.munmap.addr,
@ -94,11 +92,10 @@ static int do_ops(struct host_vm_change *hvc, int end,
break;
case MPROTECT:
if (hvc->userspace)
ret = protect(&hvc->mm->context.id,
op->u.mprotect.addr,
op->u.mprotect.len,
op->u.mprotect.prot,
finished, &hvc->data);
protect(&hvc->mm->context.id,
op->u.mprotect.addr,
op->u.mprotect.len,
op->u.mprotect.prot);
else
ret = os_protect_memory(
(void *) op->u.mprotect.addr,
@ -113,6 +110,9 @@ static int do_ops(struct host_vm_change *hvc, int end,
}
}
if (hvc->userspace && finished)
ret = syscall_stub_flush(&hvc->mm->context.id);
if (ret == -ENOMEM)
report_enomem();
@ -461,7 +461,6 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
pmd_t *pmd;
pte_t *pte;
struct mm_struct *mm = vma->vm_mm;
void *flush = NULL;
int r, w, x, prot, err = 0;
struct mm_id *mm_id;
@ -504,14 +503,13 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
int fd;
fd = phys_mapping(pte_val(*pte) & PAGE_MASK, &offset);
err = map(mm_id, address, PAGE_SIZE, prot, fd, offset,
1, &flush);
}
else err = unmap(mm_id, address, PAGE_SIZE, 1, &flush);
}
else if (pte_newprot(*pte))
err = protect(mm_id, address, PAGE_SIZE, prot, 1, &flush);
map(mm_id, address, PAGE_SIZE, prot, fd, offset);
} else
unmap(mm_id, address, PAGE_SIZE);
} else if (pte_newprot(*pte))
protect(mm_id, address, PAGE_SIZE, prot);
err = syscall_stub_flush(mm_id);
if (err) {
if (err == -ENOMEM)
report_enomem();

204
arch/um/os-Linux/skas/mem.c
View File

@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2021 Benjamin Berg <benjamin@sipsolutions.net>
* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
*/
@ -19,7 +20,7 @@
#include <sysdep/stub.h>
#include "../internal.h"
extern char batch_syscall_stub[], __syscall_stub_start[];
extern char __syscall_stub_start[];
static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
unsigned long *stack)
@ -36,22 +37,24 @@ static unsigned long syscall_regs[MAX_REG_NR];
static int __init init_syscall_regs(void)
{
get_safe_registers(syscall_regs, NULL);
syscall_regs[REGS_IP_INDEX] = STUB_CODE +
((unsigned long) batch_syscall_stub -
((unsigned long) stub_syscall_handler -
(unsigned long) __syscall_stub_start);
syscall_regs[REGS_SP_INDEX] = STUB_DATA;
syscall_regs[REGS_SP_INDEX] = STUB_DATA +
offsetof(struct stub_data, sigstack) +
sizeof(((struct stub_data *) 0)->sigstack) -
sizeof(void *);
return 0;
}
__initcall(init_syscall_regs);
static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
static inline long do_syscall_stub(struct mm_id *mm_idp)
{
struct stub_data *proc_data = (void *)mm_idp->stack;
int n, i;
long ret, offset;
unsigned long * data;
unsigned long * syscall;
int err, pid = mm_idp->u.pid;
n = ptrace_setregs(pid, syscall_regs);
@ -63,6 +66,9 @@ static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
__func__, -n);
}
/* Inform process how much we have filled in. */
proc_data->syscall_data_len = mm_idp->syscall_data_len;
err = ptrace(PTRACE_CONT, pid, 0, 0);
if (err)
panic("Failed to continue stub, pid = %d, errno = %d\n", pid,
@ -71,135 +77,113 @@ static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
wait_stub_done(pid);
/*
* When the stub stops, we find the following values on the
* beginning of the stack:
* (long )return_value
* (long )offset to failed sycall-data (0, if no error)
* proc_data->err will be non-zero if there was an (unexpected) error.
* In that case, syscall_data_len points to the last executed syscall,
* otherwise it will be zero (but we do not need to rely on that).
*/
ret = *((unsigned long *) mm_idp->stack);
offset = *((unsigned long *) mm_idp->stack + 1);
if (offset) {
data = (unsigned long *)(mm_idp->stack + offset - STUB_DATA);
printk(UM_KERN_ERR "%s : ret = %ld, offset = %ld, data = %p\n",
__func__, ret, offset, data);
syscall = (unsigned long *)((unsigned long)data + data[0]);
printk(UM_KERN_ERR "%s: syscall %ld failed, return value = 0x%lx, expected return value = 0x%lx\n",
__func__, syscall[0], ret, syscall[7]);
printk(UM_KERN_ERR " syscall parameters: 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
syscall[1], syscall[2], syscall[3],
syscall[4], syscall[5], syscall[6]);
for (n = 1; n < data[0]/sizeof(long); n++) {
if (n == 1)
printk(UM_KERN_ERR " additional syscall data:");
if (n % 4 == 1)
printk("\n" UM_KERN_ERR " ");
printk(" 0x%lx", data[n]);
}
if (n > 1)
printk("\n");
if (proc_data->err < 0) {
struct stub_syscall *sc;
if (proc_data->syscall_data_len < 0 ||
proc_data->syscall_data_len >= ARRAY_SIZE(proc_data->syscall_data))
panic("Syscall data was corrupted by stub (len is: %d, expected maximum: %d)!",
proc_data->syscall_data_len,
mm_idp->syscall_data_len);
sc = &proc_data->syscall_data[proc_data->syscall_data_len];
printk(UM_KERN_ERR "%s : length = %d, last offset = %d",
__func__, mm_idp->syscall_data_len,
proc_data->syscall_data_len);
printk(UM_KERN_ERR "%s : stub syscall type %d failed, return value = 0x%lx\n",
__func__, sc->syscall, proc_data->err);
print_hex_dump(UM_KERN_ERR,
" syscall data: ", 0,
16, 4, sc, sizeof(*sc), 0);
mm_idp->syscall_data_len = proc_data->err;
} else {
mm_idp->syscall_data_len = 0;
}
else ret = 0;
*addr = check_init_stack(mm_idp, NULL);
return ret;
return mm_idp->syscall_data_len;
}
long run_syscall_stub(struct mm_id * mm_idp, int syscall,
unsigned long *args, long expected, void **addr,
int done)
int syscall_stub_flush(struct mm_id *mm_idp)
{
unsigned long *stack = check_init_stack(mm_idp, *addr);
int res;
*stack += sizeof(long);
stack += *stack / sizeof(long);
*stack++ = syscall;
*stack++ = args[0];
*stack++ = args[1];
*stack++ = args[2];
*stack++ = args[3];
*stack++ = args[4];
*stack++ = args[5];
*stack++ = expected;
*stack = 0;
if (!done && ((((unsigned long) stack) & ~UM_KERN_PAGE_MASK) <
UM_KERN_PAGE_SIZE - 10 * sizeof(long))) {
*addr = stack;
if (mm_idp->syscall_data_len == 0)
return 0;
/* If an error happened already, report it and reset the state. */
if (mm_idp->syscall_data_len < 0) {
res = mm_idp->syscall_data_len;
mm_idp->syscall_data_len = 0;
return res;
}
return do_syscall_stub(mm_idp, addr);
res = do_syscall_stub(mm_idp);
mm_idp->syscall_data_len = 0;
return res;
}
long syscall_stub_data(struct mm_id * mm_idp,
unsigned long *data, int data_count,
void **addr, void **stub_addr)
struct stub_syscall *syscall_stub_alloc(struct mm_id *mm_idp)
{
unsigned long *stack;
int ret = 0;
struct stub_syscall *sc;
struct stub_data *proc_data = (struct stub_data *) mm_idp->stack;
/*
* If *addr still is uninitialized, it *must* contain NULL.
* Thus in this case do_syscall_stub correctly won't be called.
*/
if ((((unsigned long) *addr) & ~UM_KERN_PAGE_MASK) >=
UM_KERN_PAGE_SIZE - (10 + data_count) * sizeof(long)) {
ret = do_syscall_stub(mm_idp, addr);
/* in case of error, don't overwrite data on stack */
if (ret)
return ret;
if (mm_idp->syscall_data_len > 0 &&
mm_idp->syscall_data_len == ARRAY_SIZE(proc_data->syscall_data))
do_syscall_stub(mm_idp);
if (mm_idp->syscall_data_len < 0) {
/* Return dummy to retain error state. */
sc = &proc_data->syscall_data[0];
} else {
sc = &proc_data->syscall_data[mm_idp->syscall_data_len];
mm_idp->syscall_data_len += 1;
}
memset(sc, 0, sizeof(*sc));
stack = check_init_stack(mm_idp, *addr);
*addr = stack;
*stack = data_count * sizeof(long);
memcpy(stack + 1, data, data_count * sizeof(long));
*stub_addr = (void *)(((unsigned long)(stack + 1) &
~UM_KERN_PAGE_MASK) + STUB_DATA);
return 0;
return sc;
}
int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len, int prot,
int phys_fd, unsigned long long offset, int done, void **data)
void map(struct mm_id *mm_idp, unsigned long virt, unsigned long len, int prot,
int phys_fd, unsigned long long offset)
{
int ret;
unsigned long args[] = { virt, len, prot,
MAP_SHARED | MAP_FIXED, phys_fd,
MMAP_OFFSET(offset) };
struct stub_syscall *sc;
ret = run_syscall_stub(mm_idp, STUB_MMAP_NR, args, virt,
data, done);
return ret;
sc = syscall_stub_alloc(mm_idp);
sc->syscall = STUB_SYSCALL_MMAP;
sc->mem.addr = virt;
sc->mem.length = len;
sc->mem.prot = prot;
sc->mem.fd = phys_fd;
sc->mem.offset = MMAP_OFFSET(offset);
}
int unmap(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
int done, void **data)
void unmap(struct mm_id *mm_idp, unsigned long addr, unsigned long len)
{
int ret;
unsigned long args[] = { (unsigned long) addr, len, 0, 0, 0,
0 };
struct stub_syscall *sc;
ret = run_syscall_stub(mm_idp, __NR_munmap, args, 0,
data, done);
return ret;
sc = syscall_stub_alloc(mm_idp);
sc->syscall = STUB_SYSCALL_MUNMAP;
sc->mem.addr = addr;
sc->mem.length = len;
}
int protect(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
unsigned int prot, int done, void **data)
void protect(struct mm_id *mm_idp, unsigned long addr, unsigned long len,
unsigned int prot)
{
int ret;
unsigned long args[] = { addr, len, prot, 0, 0, 0 };
struct stub_syscall *sc;
ret = run_syscall_stub(mm_idp, __NR_mprotect, args, 0,
data, done);
return ret;
sc = syscall_stub_alloc(mm_idp);
sc->syscall = STUB_SYSCALL_MPROTECT;
sc->mem.addr = addr;
sc->mem.length = len;
sc->mem.prot = prot;
}

4
arch/um/os-Linux/skas/process.c
View File

@ -501,7 +501,7 @@ int copy_context_skas0(unsigned long new_stack, int pid)
*data = ((struct stub_data) {
.offset = MMAP_OFFSET(new_offset),
.fd = new_fd,
.parent_err = -ESRCH,
.err = -ESRCH,
.child_err = 0,
});
@ -538,7 +538,7 @@ int copy_context_skas0(unsigned long new_stack, int pid)
wait_stub_done(pid);
pid = data->parent_err;
pid = data->err;
if (pid < 0) {
printk(UM_KERN_ERR "%s - stub-parent reports error %d\n",
__func__, -pid);

2
arch/x86/um/Makefile
View File

@ -11,7 +11,7 @@ endif
obj-y = bugs_$(BITS).o delay.o fault.o ldt.o \
ptrace_$(BITS).o ptrace_user.o setjmp_$(BITS).o signal.o \
stub_$(BITS).o stub_segv.o \
stub_segv.o \
sys_call_table_$(BITS).o sysrq_$(BITS).o tls_$(BITS).o \
mem_$(BITS).o subarch.o os-Linux/

41
arch/x86/um/ldt.c
View File

@ -12,33 +12,22 @@
#include <os.h>
#include <skas.h>
#include <sysdep/tls.h>
#include <stub-data.h>
static inline int modify_ldt (int func, void *ptr, unsigned long bytecount)
{
return syscall(__NR_modify_ldt, func, ptr, bytecount);
}
static long write_ldt_entry(struct mm_id *mm_idp, int func,
struct user_desc *desc, void **addr, int done)
static void write_ldt_entry(struct mm_id *mm_idp, int func,
struct user_desc *desc)
{
long res;
void *stub_addr;
struct stub_syscall *sc;
BUILD_BUG_ON(sizeof(*desc) % sizeof(long));
res = syscall_stub_data(mm_idp, (unsigned long *)desc,
sizeof(*desc) / sizeof(long),
addr, &stub_addr);
if (!res) {
unsigned long args[] = { func,
(unsigned long)stub_addr,
sizeof(*desc),
0, 0, 0 };
res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
0, addr, done);
}
return res;
sc = syscall_stub_alloc(mm_idp);
sc->syscall = STUB_SYSCALL_LDT;
sc->ldt.func = func;
memcpy(&sc->ldt.desc, desc, sizeof(*desc));
}
/*
@ -127,7 +116,6 @@ static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
int i, err;
struct user_desc ldt_info;
struct ldt_entry entry0, *ldt_p;
void *addr = NULL;
err = -EINVAL;
if (bytecount != sizeof(ldt_info))
@ -148,7 +136,8 @@ static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
mutex_lock(&ldt->lock);
err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
write_ldt_entry(mm_idp, func, &ldt_info);
err = syscall_stub_flush(mm_idp);
if (err)
goto out_unlock;
@ -166,7 +155,8 @@ static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
err = -ENOMEM;
/* Undo the change in host */
memset(&ldt_info, 0, sizeof(ldt_info));
write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
write_ldt_entry(mm_idp, 1, &ldt_info);
err = syscall_stub_flush(mm_idp);
goto out_unlock;
}
if (i == 0) {
@ -303,7 +293,6 @@ long init_new_ldt(struct mm_context *new_mm, struct mm_context *from_mm)
short * num_p;
int i;
long page, err=0;
void *addr = NULL;
mutex_init(&new_mm->arch.ldt.lock);
@ -318,11 +307,9 @@ long init_new_ldt(struct mm_context *new_mm, struct mm_context *from_mm)
ldt_get_host_info();
for (num_p=host_ldt_entries; *num_p != -1; num_p++) {
desc.entry_number = *num_p;
err = write_ldt_entry(&new_mm->id, 1, &desc,
&addr, *(num_p + 1) == -1);
if (err)
break;
write_ldt_entry(&new_mm->id, 1, &desc);
}
err = syscall_stub_flush(&new_mm->id);
new_mm->arch.ldt.entry_count = 0;
goto out;

1
arch/x86/um/shared/sysdep/stub.h
View File

@ -12,4 +12,5 @@
#endif
extern void stub_segv_handler(int, siginfo_t *, void *);
extern void stub_syscall_handler(void);
extern void stub_clone_handler(void);

56
arch/x86/um/stub_32.S
View File

@ -1,56 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
#include <as-layout.h>
.section .__syscall_stub, "ax"
.globl batch_syscall_stub
batch_syscall_stub:
/* %esp comes in as "top of page" */
mov %esp, %ecx
/* %esp has pointer to first operation */
add $8, %esp
again:
/* load length of additional data */
mov 0x0(%esp), %eax
/* if(length == 0) : end of list */
/* write possible 0 to header */
mov %eax, 0x4(%ecx)
cmpl $0, %eax
jz done
/* save current pointer */
mov %esp, 0x4(%ecx)
/* skip additional data */
add %eax, %esp
/* load syscall-# */
pop %eax
/* load syscall params */
pop %ebx
pop %ecx
pop %edx
pop %esi
pop %edi
pop %ebp
/* execute syscall */
int $0x80
/* restore top of page pointer in %ecx */
mov %esp, %ecx
andl $(~UM_KERN_PAGE_SIZE) + 1, %ecx
/* check return value */
pop %ebx
cmp %ebx, %eax
je again
done:
/* save return value */
mov %eax, (%ecx)
/* stop */
int3

50
arch/x86/um/stub_64.S
View File

@ -1,50 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
#include <as-layout.h>
.section .__syscall_stub, "ax"
.globl batch_syscall_stub
batch_syscall_stub:
/* %rsp has the pointer to first operation */
mov %rsp, %rbx
add $0x10, %rsp
again:
/* load length of additional data */
mov 0x0(%rsp), %rax
/* if(length == 0) : end of list */
/* write possible 0 to header */
mov %rax, 8(%rbx)
cmp $0, %rax
jz done
/* save current pointer */
mov %rsp, 8(%rbx)
/* skip additional data */
add %rax, %rsp
/* load syscall-# */
pop %rax
/* load syscall params */
pop %rdi
pop %rsi
pop %rdx
pop %r10
pop %r8
pop %r9
/* execute syscall */
syscall
/* check return value */
pop %rcx
cmp %rcx, %rax
je again
done:
/* save return value */
mov %rax, (%rbx)
/* stop */
int3