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Tue, 29 Apr 2025 21:27:44 -0700 (PDT) Received: by ikb-h07-29-noble.in.iijlab.net (Postfix, from userid 1010) id 2BA51E94818; Wed, 30 Apr 2025 13:27:42 +0900 (JST) From: Hajime Tazaki To: linux-um@lists.infradead.org Cc: thehajime@gmail.com, ricarkol@google.com, Liam.Howlett@oracle.com, linux-kernel@vger.kernel.org Subject: [PATCH v8 03/12] um: nommu: memory handling Date: Wed, 30 Apr 2025 13:27:09 +0900 Message-ID: <2598e5207a53e4ec1f2077b5c5a9f03fc3782506.1745980082.git.thehajime@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Signed-off-by: Ricardo Koller --- 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 :=3D -I$(srctree)/$(SHARED_HEADERS) ARCH_INCLUDE +=3D -I$(srctree)/$(HOST_DIR)/um/shared KBUILD_CPPFLAGS +=3D -I$(srctree)/$(HOST_DIR)/um =20 +ifneq ($(CONFIG_MMU),y) +core-y +=3D $(ARCH_DIR)/nommu/ +endif + # -Dvmap=3Dkernel_vmap prevents anything from referencing the libpcap.o sy= mbol so # named - it's a common symbol in libpcap, so we get a binary which crashe= s. # 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 =20 =20 +#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 +#endif =20 #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; =20 +#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; =20 #endif diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_co= ntext.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, st= ruct mm_struct *next, } } =20 +#ifdef CONFIG_MMU #define init_new_context init_new_context extern int init_new_context(struct task_struct *task, struct mm_struct *mm= ); =20 #define destroy_context destroy_context extern void destroy_context(struct mm_struct *mm); +#endif =20 #include =20 diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h index 3a08f9029a3f..eb9b7d577062 100644 --- a/arch/um/include/asm/uaccess.h +++ b/arch/um/include/asm/uaccess.h @@ -23,6 +23,7 @@ #define __addr_range_nowrap(addr, size) \ ((unsigned long) (addr) <=3D ((unsigned long) (addr) + (size))) =20 +#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, u= nsigned long n); extern unsigned long __clear_user(void __user *mem, unsigned long len); @@ -34,9 +35,6 @@ static inline int __access_ok(const void __user *ptr, uns= igned long size); =20 #define INLINE_COPY_FROM_USER #define INLINE_COPY_TO_USER - -#include - static inline int __access_ok(const void __user *ptr, unsigned long size) { unsigned long addr =3D (unsigned long)ptr; @@ -68,5 +66,8 @@ do { \ put_unaligned(*((type *)src), (type *)(dst)); \ current->thread.segv_continue =3D NULL; \ } while (0) +#endif + +#include =20 #endif diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c index cbe8b9d03d8c..1e18384381e2 100644 --- a/arch/um/kernel/mem.c +++ b/arch/um/kernel/mem.c @@ -64,7 +64,8 @@ void __init mem_init(void) * to be turned on. */ brk_end =3D (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 =3D brk_end; min_low_pfn =3D PFN_UP(__pa(uml_reserved)); 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; =20 + /* NOMMU kernel uses -1 as a fd for further use (e.g., mmap) */ + if (!IS_ENABLED(CONFIG_MMU)) + return -1; + fd =3D create_tmp_file(len); =20 err =3D os_set_exec_close(fd); diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c index 2331e32c4898..8a615875d1a1 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 =3D (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) | (x ? PROT_EXEC : 0); =20 - loc =3D mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED, - fd, off); + loc =3D mmap64((void *) virt, len, prot, MAP_SHARED | MAP_FIXED | + (!IS_ENABLED(CONFIG_MMU) ? MAP_ANONYMOUS : 0), fd, off); if (loc =3D=3D MAP_FAILED) return -errno; return 0; --=20 2.43.0