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um: remove copy_from_kernel_nofault_allowed

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[ Upstream commit 84a6fc378471fbeaf48f8604566a5a33a3d63c18 ]

There is no need to override the default version of this function
anymore as UML now has proper _nofault memory access functions.

Doing this also fixes the fact that the implementation was incorrect as
using mincore() will incorrectly flag pages as inaccessible if they were
swapped out by the host.

Fixes: f75b1b1bed ("um: Implement probe_kernel_read()")
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20250210160926.420133-3-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Benjamin Berg 2025-02-10 17:09:26 +01:00 committed by Greg Kroah-Hartman
parent 142f89201e
commit b0686d0d76
4 changed files with 1 additions and 72 deletions
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1
arch/um/include/shared/os.h
View File

@ -211,7 +211,6 @@ extern int os_protect_memory(void *addr, unsigned long len,
extern int os_unmap_memory(void *addr, int len);
extern int os_drop_memory(void *addr, int length);
extern int can_drop_memory(void);
extern int os_mincore(void *addr, unsigned long len);
/* execvp.c */
extern int execvp_noalloc(char *buf, const char *file, char *const argv[]);

2
arch/um/kernel/Makefile
View File

@ -17,7 +17,7 @@ extra-y := vmlinux.lds
obj-y = config.o exec.o exitcode.o irq.o ksyms.o mem.o \
physmem.o process.o ptrace.o reboot.o sigio.o \
signal.o sysrq.o time.o tlb.o trap.o \
um_arch.o umid.o maccess.o kmsg_dump.o capflags.o skas/
um_arch.o umid.o kmsg_dump.o capflags.o skas/
obj-y += load_file.o
obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o

19
arch/um/kernel/maccess.c
View File

@ -1,19 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2013 Richard Weinberger <richrd@nod.at>
*/
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <os.h>
bool copy_from_kernel_nofault_allowed(const void *src, size_t size)
{
void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
if ((unsigned long)src < PAGE_SIZE || size <= 0)
return false;
if (os_mincore(psrc, size + src - psrc) <= 0)
return false;
return true;
}

51
arch/um/os-Linux/process.c
View File

@ -223,57 +223,6 @@ out:
return ok;
}
static int os_page_mincore(void *addr)
{
char vec[2];
int ret;
ret = mincore(addr, UM_KERN_PAGE_SIZE, vec);
if (ret < 0) {
if (errno == ENOMEM || errno == EINVAL)
return 0;
else
return -errno;
}
return vec[0] & 1;
}
int os_mincore(void *addr, unsigned long len)
{
char *vec;
int ret, i;
if (len <= UM_KERN_PAGE_SIZE)
return os_page_mincore(addr);
vec = calloc(1, (len + UM_KERN_PAGE_SIZE - 1) / UM_KERN_PAGE_SIZE);
if (!vec)
return -ENOMEM;
ret = mincore(addr, UM_KERN_PAGE_SIZE, vec);
if (ret < 0) {
if (errno == ENOMEM || errno == EINVAL)
ret = 0;
else
ret = -errno;
goto out;
}
for (i = 0; i < ((len + UM_KERN_PAGE_SIZE - 1) / UM_KERN_PAGE_SIZE); i++) {
if (!(vec[i] & 1)) {
ret = 0;
goto out;
}
}
ret = 1;
out:
free(vec);
return ret;
}
void init_new_thread_signals(void)
{
set_handler(SIGSEGV);