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newlib: fix heap user mode access for MPU devices

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MPU devices that enforce power-of-two alignment now
specify the size of the buffer used for the newlib heap.
This buffer will be properly aligned and a pointer
exposed in a kernel header, such that it can be added
to a user thread's memory domain configuration if
necessary.

MPU devices that don't have these restrictions allocate
the heap as normal.

In all cases, if an MPU/MMU region needs to be programmed,
the z_newlib_get_heap_bounds() API will return the necessary
information.

Given how precious MPU regions are, no automatic programming
of the MPU is done; applications will need to do this as
needed in their memory domain configurations.

On x86, the x86 MMU-specific code has been moved to arch/x86
using the new z_newlib_get_heap_bounds() API.

Fixes: #6814

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2018-05-09 16:36:44 -07:00 • committed by Andrew Boie
commit 42a2c96422
4 changed files with 71 additions and 20 deletions
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32
lib/libc/newlib/libc-hooks.c
View file

@ -10,10 +10,17 @@
#include <sys/stat.h>
#include <linker/linker-defs.h>
#include <misc/util.h>
#include <init.h>
#include <kernel_internal.h>
#define USED_RAM_END_ADDR POINTER_TO_UINT(&_end)
#if CONFIG_NEWLIB_LIBC_ALIGNED_HEAP_SIZE
/* Compiler will throw an error if the provided value isn't a power of two */
static unsigned char __kernel __aligned(CONFIG_NEWLIB_LIBC_ALIGNED_HEAP_SIZE)
heap_base[CONFIG_NEWLIB_LIBC_ALIGNED_HEAP_SIZE];
#define MAX_HEAP_SIZE CONFIG_NEWLIB_LIBC_ALIGNED_HEAP_SIZE
#else
#if CONFIG_X86
#define USED_RAM_SIZE (USED_RAM_END_ADDR - CONFIG_PHYS_RAM_ADDR)
#define MAX_HEAP_SIZE ((KB(CONFIG_RAM_SIZE)) - USED_RAM_SIZE)
@ -38,6 +45,8 @@ extern void *_heap_sentry;
#endif
static unsigned char *heap_base = UINT_TO_POINTER(USED_RAM_END_ADDR);
#endif /* CONFIG_NEWLIB_LIBC_ALIGNED_HEAP_SIZE */
static unsigned int heap_sz;
static int _stdout_hook_default(int c)
@ -159,23 +168,8 @@ void *_sbrk(int count)
}
FUNC_ALIAS(_sbrk, sbrk, void *);
#ifdef CONFIG_X86_MMU
static int newlib_mmu_prepare(struct device *unused)
void z_newlib_get_heap_bounds(void **base, size_t *size)
{
ARG_UNUSED(unused);
/* Set up the newlib heap area as a globally user-writable region.
* We can't do this at build time with MMU_BOOT_REGION() as the _end
* pointer shifts significantly between build phases due to the
* introduction of page tables.
*/
_x86_mmu_set_flags(UINT_TO_POINTER(USED_RAM_END_ADDR), MAX_HEAP_SIZE,
MMU_ENTRY_PRESENT | MMU_ENTRY_WRITE |
MMU_ENTRY_USER,
MMU_PTE_P_MASK | MMU_PTE_RW_MASK | MMU_PTE_US_MASK);
return 0;
*base = heap_base;
*size = MAX_HEAP_SIZE;
}
SYS_INIT(newlib_mmu_prepare, APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
#endif /* CONFIG_X86_MMU */