[PATCH v5 04/13] um: nommu: memory handling
Hajime Tazaki
thehajime at gmail.com
Thu Dec 12 02:12:11 PST 2024
This commit adds memory operations on UML under !MMU environment.
Some part of the original UML code relying on CONFIG_MMU are excluded
from compilation when !CONFIG_MMU. Additionally, generic functions such as
uaccess, futex, memcpy/strnlen/strncpy can be used as user- and
kernel-space share the address space in !CONFIG_MMU mode.
Signed-off-by: Hajime Tazaki <thehajime at gmail.com>
Signed-off-by: Ricardo Koller <ricarkol at google.com>
---
arch/um/Makefile | 4 ++++
arch/um/include/asm/futex.h | 4 ++++
arch/um/include/asm/mmu.h | 3 +++
arch/um/include/asm/mmu_context.h | 2 ++
arch/um/include/asm/uaccess.h | 7 ++++---
arch/um/kernel/mem.c | 3 ++-
arch/um/os-Linux/mem.c | 4 ++++
arch/um/os-Linux/process.c | 4 ++--
8 files changed, 25 insertions(+), 6 deletions(-)
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 1d36a613aad8..fcf4bb915a31 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -46,6 +46,10 @@ ARCH_INCLUDE := -I$(srctree)/$(SHARED_HEADERS)
ARCH_INCLUDE += -I$(srctree)/$(HOST_DIR)/um/shared
KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/um
+ifneq ($(CONFIG_MMU),y)
+core-y += $(ARCH_DIR)/nommu/
+endif
+
# -Dvmap=kernel_vmap prevents anything from referencing the libpcap.o symbol so
# named - it's a common symbol in libpcap, so we get a binary which crashes.
#
diff --git a/arch/um/include/asm/futex.h b/arch/um/include/asm/futex.h
index 780aa6bfc050..785fd6649aa2 100644
--- a/arch/um/include/asm/futex.h
+++ b/arch/um/include/asm/futex.h
@@ -7,8 +7,12 @@
#include <asm/errno.h>
+#ifdef CONFIG_MMU
int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr);
int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval);
+#else
+#include <asm-generic/futex.h>
+#endif
#endif
diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index 01422b761aa0..d4087f9499e2 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -15,10 +15,13 @@ typedef struct mm_context {
unsigned long sync_tlb_range_from;
unsigned long sync_tlb_range_to;
+#ifndef CONFIG_MMU
+ unsigned long end_brk;
#ifdef CONFIG_BINFMT_ELF_FDPIC
unsigned long exec_fdpic_loadmap;
unsigned long interp_fdpic_loadmap;
#endif
+#endif /* !CONFIG_MMU */
} mm_context_t;
#endif
diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
index 23dcc914d44e..033a70166066 100644
--- a/arch/um/include/asm/mmu_context.h
+++ b/arch/um/include/asm/mmu_context.h
@@ -36,11 +36,13 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
}
}
+#ifdef CONFIG_MMU
#define init_new_context init_new_context
extern int init_new_context(struct task_struct *task, struct mm_struct *mm);
#define destroy_context destroy_context
extern void destroy_context(struct mm_struct *mm);
+#endif
#include <asm-generic/mmu_context.h>
diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h
index 1d4b6bbc1b65..9bfee12cb6b7 100644
--- a/arch/um/include/asm/uaccess.h
+++ b/arch/um/include/asm/uaccess.h
@@ -22,6 +22,7 @@
#define __addr_range_nowrap(addr, size) \
((unsigned long) (addr) <= ((unsigned long) (addr) + (size)))
+#ifdef CONFIG_MMU
extern unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n);
extern unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n);
extern unsigned long __clear_user(void __user *mem, unsigned long len);
@@ -33,9 +34,6 @@ static inline int __access_ok(const void __user *ptr, unsigned long size);
#define INLINE_COPY_FROM_USER
#define INLINE_COPY_TO_USER
-
-#include <asm-generic/uaccess.h>
-
static inline int __access_ok(const void __user *ptr, unsigned long size)
{
unsigned long addr = (unsigned long)ptr;
@@ -43,6 +41,9 @@ static inline int __access_ok(const void __user *ptr, unsigned long size)
(__under_task_size(addr, size) ||
__access_ok_vsyscall(addr, size));
}
+#endif
+
+#include <asm-generic/uaccess.h>
/* no pagefaults for kernel addresses in um */
#define __get_kernel_nofault(dst, src, type, err_label) \
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index e3a7ec32d6c7..f82f54bc6920 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -63,7 +63,8 @@ void __init mem_init(void)
* to be turned on.
*/
brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
- map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
+ map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1,
+ !IS_ENABLED(CONFIG_MMU));
memblock_free((void *)brk_end, uml_reserved - brk_end);
uml_reserved = brk_end;
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 72f302f4d197..4f5d9a94f8e2 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -213,6 +213,10 @@ int __init create_mem_file(unsigned long long len)
{
int err, fd;
+ /* NOMMU kernel uses -1 as a fd for further use (e.g., mmap) */
+ if (!IS_ENABLED(CONFIG_MMU))
+ return -1;
+
fd = create_tmp_file(len);
err = os_set_exec_close(fd);
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index 6df378639880..e2dc00fc84c0 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -70,8 +70,8 @@ int os_map_memory(void *virt, int fd, unsigned long long off, unsigned long len,
prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
(x ? PROT_EXEC : 0);
- loc = mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED,
- fd, off);
+ loc = mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED |
+ (!IS_ENABLED(CONFIG_MMU) ? MAP_ANONYMOUS : 0), fd, off);
if (loc == MAP_FAILED)
return -errno;
return 0;
--
2.43.0
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