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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-10-13 11:49:00 +0200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-10-17 14:04:11 +0200 |
| commit | 8bb4e76704c4ec1c923ae75f806478360d51b403 (patch) | |
| tree | 387406b17a7265e78f682ff2678a6ec14cc47c13 | |
| parent | 435f231ac94ccf5bc0fc343dc00b617bdd7519c5 (diff) | |
| download | man-pages-8bb4e76704c4ec1c923ae75f806478360d51b403.tar.gz | |
pkeys.7: Cosmetic changes to example program
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
| -rw-r--r-- | man7/pkeys.7 | 87 |
1 files changed, 55 insertions, 32 deletions
diff --git a/man7/pkeys.7 b/man7/pkeys.7 index b35d16cbf0..142423c631 100644 --- a/man7/pkeys.7 +++ b/man7/pkeys.7 @@ -165,81 +165,104 @@ Segmentation fault (core dumped) #include <stdio.h> #include <sys/mman.h> -static inline void wrpkru(unsigned int pkru) +static inline void +wrpkru(unsigned int pkru) { - unsigned int eax = pkru; - unsigned int ecx = 0; - unsigned int edx = 0; + unsigned int eax = pkru; + unsigned int ecx = 0; + unsigned int edx = 0; - asm volatile(".byte 0x0f,0x01,0xef\n\t" - : : "a" (eax), "c" (ecx), "d" (edx)); + asm volatile(".byte 0x0f,0x01,0xef\\n\\t" + : : "a" (eax), "c" (ecx), "d" (edx)); } -int pkey_set(int pkey, unsigned long rights, unsigned long flags) +int +pkey_set(int pkey, unsigned long rights, unsigned long flags) { - unsigned int pkru = (rights << (2*pkey)); + unsigned int pkru = (rights << (2 * pkey)); return wrpkru(pkru); } -int pkey_mprotect(void *ptr, size_t size, unsigned long orig_prot, unsigned long pkey) +int +pkey_mprotect(void *ptr, size_t size, unsigned long orig_prot, + unsigned long pkey) { return syscall(SYS_pkey_mprotect, ptr, size, orig_prot, pkey); } -int pkey_alloc(void) +int +pkey_alloc(void) { return syscall(SYS_pkey_alloc, 0, 0); } -int pkey_free(unsigned long pkey) +int +pkey_free(unsigned long pkey) { return syscall(SYS_pkey_free, pkey); } -int main(void) +#define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \\ + } while (0) + +int +main(void) { int status; int pkey; int *buffer; - /* Allocate one page of memory: */ - buffer = mmap(NULL, getpagesize(), PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); + /* + *Allocate one page of memory + */ + buffer = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE, \-1, 0); if (buffer == MAP_FAILED) - return -ENOMEM; + errExit("mmap"); - /* Put some random data in to the page (still OK to touch): */ - (*buffer) = __LINE__; + /* + * Put some random data into the page (still OK to touch) + */ + *buffer = __LINE__; printf("buffer contains: %d\\n", *buffer); - /* Allocate a protection key: */ + /* + * Allocate a protection key: + */ pkey = pkey_alloc(); - if (pkey < 0) - return pkey; + if (pkey == \-1) + errExit("pkey_alloc"); - /* Disable access to any memory with "pkey" set, - * even though there is none right now. */ + /* + * Disable access to any memory with "pkey" set, + * even though there is none right now + */ status = pkey_set(pkey, PKEY_DISABLE_ACCESS, 0); if (status) - return status; + errExit("pkey_set"); /* - * set the protection key on "buffer": - * Note that it is still read/write as far as mprotect() is, + * Set the protection key on "buffer". + * Note that it is still read/write as far as mprotect() is * concerned and the previous pkey_set() overrides it. */ - status = pkey_mprotect(buffer, getpagesize(), PROT_READ|PROT_WRITE, pkey); - if (status) - return status; + status = pkey_mprotect(buffer, getpagesize(), + PROT_READ | PROT_WRITE, pkey); + if (status == -1) + errExit("pkey_mprotect"); printf("about to read buffer again...\\n"); - /* this will crash, because we have disallowed access: */ + + /* + * This will crash, because we have disallowed access + */ printf("buffer contains: %d\\n", *buffer); status = pkey_free(pkey); - if (status) - return status; + if (status == -1) + errExit("pkey_free"); - return 0; + exit(EXIT_SUCCESS); } .SH SEE ALSO .BR pkey_alloc (2), |