From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas at arm.com (Catalin Marinas) Date: Wed, 22 May 2019 15:16:12 +0100 Subject: [PATCH v15 17/17] selftests, arm64: add a selftest for passing tagged pointers to kernel In-Reply-To: References: Message-ID: <20190522141612.GA28122@arrakis.emea.arm.com> On Mon, May 06, 2019 at 06:31:03PM +0200, Andrey Konovalov wrote: > This patch is a part of a series that extends arm64 kernel ABI to allow to > pass tagged user pointers (with the top byte set to something else other > than 0x00) as syscall arguments. > > This patch adds a simple test, that calls the uname syscall with a > tagged user pointer as an argument. Without the kernel accepting tagged > user pointers the test fails with EFAULT. That's probably sufficient for a simple example. Something we could add to Documentation maybe is a small library that can be LD_PRELOAD'ed so that you can run a lot more tests like LTP. We could add this to selftests but I think it's too glibc specific. --------------------8<------------------------------------ #include #define TAG_SHIFT (56) #define TAG_MASK (0xffUL << TAG_SHIFT) void *__libc_malloc(size_t size); void __libc_free(void *ptr); void *__libc_realloc(void *ptr, size_t size); void *__libc_calloc(size_t nmemb, size_t size); static void *tag_ptr(void *ptr) { unsigned long tag = rand() & 0xff; if (!ptr) return ptr; return (void *)((unsigned long)ptr | (tag << TAG_SHIFT)); } static void *untag_ptr(void *ptr) { return (void *)((unsigned long)ptr & ~TAG_MASK); } void *malloc(size_t size) { return tag_ptr(__libc_malloc(size)); } void free(void *ptr) { __libc_free(untag_ptr(ptr)); } void *realloc(void *ptr, size_t size) { return tag_ptr(__libc_realloc(untag_ptr(ptr), size)); } void *calloc(size_t nmemb, size_t size) { return tag_ptr(__libc_calloc(nmemb, size)); } From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Wed, 22 May 2019 15:16:12 +0100 Subject: [PATCH v15 17/17] selftests, arm64: add a selftest for passing tagged pointers to kernel In-Reply-To: References: Message-ID: <20190522141612.GA28122@arrakis.emea.arm.com> Content-Type: text/plain; charset="UTF-8" Message-ID: <20190522141612.p9Rb9qJgapiMpVTTZhGvNpsqcKEHBmCqjHSavnWExN0@z> On Mon, May 06, 2019@06:31:03PM +0200, Andrey Konovalov wrote: > This patch is a part of a series that extends arm64 kernel ABI to allow to > pass tagged user pointers (with the top byte set to something else other > than 0x00) as syscall arguments. > > This patch adds a simple test, that calls the uname syscall with a > tagged user pointer as an argument. Without the kernel accepting tagged > user pointers the test fails with EFAULT. That's probably sufficient for a simple example. Something we could add to Documentation maybe is a small library that can be LD_PRELOAD'ed so that you can run a lot more tests like LTP. We could add this to selftests but I think it's too glibc specific. --------------------8<------------------------------------ #include #define TAG_SHIFT (56) #define TAG_MASK (0xffUL << TAG_SHIFT) void *__libc_malloc(size_t size); void __libc_free(void *ptr); void *__libc_realloc(void *ptr, size_t size); void *__libc_calloc(size_t nmemb, size_t size); static void *tag_ptr(void *ptr) { unsigned long tag = rand() & 0xff; if (!ptr) return ptr; return (void *)((unsigned long)ptr | (tag << TAG_SHIFT)); } static void *untag_ptr(void *ptr) { return (void *)((unsigned long)ptr & ~TAG_MASK); } void *malloc(size_t size) { return tag_ptr(__libc_malloc(size)); } void free(void *ptr) { __libc_free(untag_ptr(ptr)); } void *realloc(void *ptr, size_t size) { return tag_ptr(__libc_realloc(untag_ptr(ptr), size)); } void *calloc(size_t nmemb, size_t size) { return tag_ptr(__libc_calloc(nmemb, size)); }