mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-25 02:40:54 +07:00
c576eddf1c
Right now several architectures allow their set_memory_*() family of
functions to fail, but callers may not be checking the return values.
If set_memory_*() returns with an error, call-site assumptions may be
infact wrong to assume that it would either succeed or not succeed at
all. Ideally, the failure of set_memory_*() should be passed up the call
stack, and callers should examine the failure and deal with it.
Need to fix the callers and add the __must_check attribute. They also
may not provide any level of atomicity, in the sense that the memory
protections may be left incomplete on failure. This issue likely has a
few steps on effects architectures:
1) Have all callers of set_memory_*() helpers check the return value.
2) Add __must_check to all set_memory_*() helpers so that new uses do
not ignore the return value.
3) Add atomicity to the calls so that the memory protections aren't
left in a partial state.
This series is part of step 1. Make sram driver check the return value
of set_memory_*().
Signed-off-by: Tianlin Li <tli@digitalocean.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20191217194528.16461-1-tli@digitalocean.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
133 lines
3.8 KiB
C
133 lines
3.8 KiB
C
/*
|
|
* SRAM protect-exec region helper functions
|
|
*
|
|
* Copyright (C) 2017 Texas Instruments Incorporated - http://www.ti.com/
|
|
* Dave Gerlach
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
|
|
* kind, whether express or implied; without even the implied warranty
|
|
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*/
|
|
|
|
#include <linux/device.h>
|
|
#include <linux/genalloc.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/sram.h>
|
|
|
|
#include <asm/fncpy.h>
|
|
#include <asm/set_memory.h>
|
|
|
|
#include "sram.h"
|
|
|
|
static DEFINE_MUTEX(exec_pool_list_mutex);
|
|
static LIST_HEAD(exec_pool_list);
|
|
|
|
int sram_check_protect_exec(struct sram_dev *sram, struct sram_reserve *block,
|
|
struct sram_partition *part)
|
|
{
|
|
unsigned long base = (unsigned long)part->base;
|
|
unsigned long end = base + block->size;
|
|
|
|
if (!PAGE_ALIGNED(base) || !PAGE_ALIGNED(end)) {
|
|
dev_err(sram->dev,
|
|
"SRAM pool marked with 'protect-exec' is not page aligned and will not be created.\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int sram_add_protect_exec(struct sram_partition *part)
|
|
{
|
|
mutex_lock(&exec_pool_list_mutex);
|
|
list_add_tail(&part->list, &exec_pool_list);
|
|
mutex_unlock(&exec_pool_list_mutex);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* sram_exec_copy - copy data to a protected executable region of sram
|
|
*
|
|
* @pool: struct gen_pool retrieved that is part of this sram
|
|
* @dst: Destination address for the copy, that must be inside pool
|
|
* @src: Source address for the data to copy
|
|
* @size: Size of copy to perform, which starting from dst, must reside in pool
|
|
*
|
|
* Return: Address for copied data that can safely be called through function
|
|
* pointer, or NULL if problem.
|
|
*
|
|
* This helper function allows sram driver to act as central control location
|
|
* of 'protect-exec' pools which are normal sram pools but are always set
|
|
* read-only and executable except when copying data to them, at which point
|
|
* they are set to read-write non-executable, to make sure no memory is
|
|
* writeable and executable at the same time. This region must be page-aligned
|
|
* and is checked during probe, otherwise page attribute manipulation would
|
|
* not be possible. Care must be taken to only call the returned address as
|
|
* dst address is not guaranteed to be safely callable.
|
|
*
|
|
* NOTE: This function uses the fncpy macro to move code to the executable
|
|
* region. Some architectures have strict requirements for relocating
|
|
* executable code, so fncpy is a macro that must be defined by any arch
|
|
* making use of this functionality that guarantees a safe copy of exec
|
|
* data and returns a safe address that can be called as a C function
|
|
* pointer.
|
|
*/
|
|
void *sram_exec_copy(struct gen_pool *pool, void *dst, void *src,
|
|
size_t size)
|
|
{
|
|
struct sram_partition *part = NULL, *p;
|
|
unsigned long base;
|
|
int pages;
|
|
void *dst_cpy;
|
|
int ret;
|
|
|
|
mutex_lock(&exec_pool_list_mutex);
|
|
list_for_each_entry(p, &exec_pool_list, list) {
|
|
if (p->pool == pool)
|
|
part = p;
|
|
}
|
|
mutex_unlock(&exec_pool_list_mutex);
|
|
|
|
if (!part)
|
|
return NULL;
|
|
|
|
if (!gen_pool_has_addr(pool, (unsigned long)dst, size))
|
|
return NULL;
|
|
|
|
base = (unsigned long)part->base;
|
|
pages = PAGE_ALIGN(size) / PAGE_SIZE;
|
|
|
|
mutex_lock(&part->lock);
|
|
|
|
ret = set_memory_nx((unsigned long)base, pages);
|
|
if (ret)
|
|
goto error_out;
|
|
ret = set_memory_rw((unsigned long)base, pages);
|
|
if (ret)
|
|
goto error_out;
|
|
|
|
dst_cpy = fncpy(dst, src, size);
|
|
|
|
ret = set_memory_ro((unsigned long)base, pages);
|
|
if (ret)
|
|
goto error_out;
|
|
ret = set_memory_x((unsigned long)base, pages);
|
|
if (ret)
|
|
goto error_out;
|
|
|
|
mutex_unlock(&part->lock);
|
|
|
|
return dst_cpy;
|
|
|
|
error_out:
|
|
mutex_unlock(&part->lock);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sram_exec_copy);
|