| Message ID | 1474970326-10271-2-git-send-email-pl@kamp.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Am 27.09.2016 um 11:58 hat Peter Lieven geschrieben: > the allocated stack will be adjusted to the minimum supported stack size > by the OS and rounded up to be a multiple of the system pagesize. > Additionally an architecture dependent guard page is added to the stack > to catch stack overflows. > > Signed-off-by: Peter Lieven <pl@kamp.de> > --- > include/sysemu/os-posix.h | 27 +++++++++++++++++++++++++++ > util/oslib-posix.c | 42 ++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 69 insertions(+) > > diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h > index 9c7dfdf..3cfedbc 100644 > --- a/include/sysemu/os-posix.h > +++ b/include/sysemu/os-posix.h > @@ -60,4 +60,31 @@ int qemu_utimens(const char *path, const qemu_timespec *times); > > bool is_daemonized(void); > > +/** > + * qemu_alloc_stack: > + * @sz: pointer to a size_t holding the requested usable stack size > + * > + * Allocate memory that can be used as a stack, for instance for > + * coroutines. If the memory cannot be allocated, this function > + * will abort (like g_malloc()). This function also inserts an > + * additional guard page to catch a potential stack overflow. > + * Note that the memory required for the guard page and alignment > + * and minimal stack size restrictions will increase the value of sz. > + * > + * The allocated stack must be freed with qemu_free_stack(). > + * > + * Returns: pointer to (the lowest address of) the stack memory. > + */ > +void *qemu_alloc_stack(size_t *sz); > + > +/** > + * qemu_free_stack: > + * @stack: stack to free > + * @sz: size of stack in bytes > + * > + * Free a stack allocated via qemu_alloc_stack(). Note that sz must > + * be exactly the adjusted stack size returned by qemu_alloc_stack. > + */ > +void qemu_free_stack(void *stack, size_t sz); > + > #endif > diff --git a/util/oslib-posix.c b/util/oslib-posix.c > index f2d4e9e..5745229 100644 > --- a/util/oslib-posix.c > +++ b/util/oslib-posix.c > @@ -499,3 +499,45 @@ pid_t qemu_fork(Error **errp) > } > return pid; > } > + > +void *qemu_alloc_stack(size_t *sz) > +{ > + void *ptr, *guardpage; > + size_t pagesz = getpagesize(); > +#ifdef _SC_THREAD_STACK_MIN > + /* avoid stacks smaller than _SC_THREAD_STACK_MIN */ > + long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN); > + *sz = MAX(MAX(min_stack_sz, 0), *sz); > +#endif > + /* adjust stack size to a multiple of the page size */ > + *sz = ROUND_UP(*sz, pagesz); > + /* allocate one extra page for the guard page */ > + *sz += pagesz; > + > + ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, > + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); > + if (ptr == MAP_FAILED) { > + abort(); > + } > + > +#if defined(HOST_IA64) > + /* separate register stack */ > + guardpage = ptr + (((sz - pagesz) / 2) & ~pagesz); s/sz/*sz/ > +#elif defined(HOST_HPPA) > + /* stack grows up */ > + guardpage = ptr + sz - pagesz; Here too. I can fix both while applying the series. > +#else > + /* stack grows down */ > + guardpage = ptr; > +#endif > + if (mprotect(guardpage, pagesz, PROT_NONE) != 0) { > + abort(); > + } > + > + return ptr; > +} Kevin
Am 27.09.2016 um 13:59 schrieb Kevin Wolf: > Am 27.09.2016 um 11:58 hat Peter Lieven geschrieben: >> the allocated stack will be adjusted to the minimum supported stack size >> by the OS and rounded up to be a multiple of the system pagesize. >> Additionally an architecture dependent guard page is added to the stack >> to catch stack overflows. >> >> Signed-off-by: Peter Lieven <pl@kamp.de> >> --- >> include/sysemu/os-posix.h | 27 +++++++++++++++++++++++++++ >> util/oslib-posix.c | 42 ++++++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 69 insertions(+) >> >> diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h >> index 9c7dfdf..3cfedbc 100644 >> --- a/include/sysemu/os-posix.h >> +++ b/include/sysemu/os-posix.h >> @@ -60,4 +60,31 @@ int qemu_utimens(const char *path, const qemu_timespec *times); >> >> bool is_daemonized(void); >> >> +/** >> + * qemu_alloc_stack: >> + * @sz: pointer to a size_t holding the requested usable stack size >> + * >> + * Allocate memory that can be used as a stack, for instance for >> + * coroutines. If the memory cannot be allocated, this function >> + * will abort (like g_malloc()). This function also inserts an >> + * additional guard page to catch a potential stack overflow. >> + * Note that the memory required for the guard page and alignment >> + * and minimal stack size restrictions will increase the value of sz. >> + * >> + * The allocated stack must be freed with qemu_free_stack(). >> + * >> + * Returns: pointer to (the lowest address of) the stack memory. >> + */ >> +void *qemu_alloc_stack(size_t *sz); >> + >> +/** >> + * qemu_free_stack: >> + * @stack: stack to free >> + * @sz: size of stack in bytes >> + * >> + * Free a stack allocated via qemu_alloc_stack(). Note that sz must >> + * be exactly the adjusted stack size returned by qemu_alloc_stack. >> + */ >> +void qemu_free_stack(void *stack, size_t sz); >> + >> #endif >> diff --git a/util/oslib-posix.c b/util/oslib-posix.c >> index f2d4e9e..5745229 100644 >> --- a/util/oslib-posix.c >> +++ b/util/oslib-posix.c >> @@ -499,3 +499,45 @@ pid_t qemu_fork(Error **errp) >> } >> return pid; >> } >> + >> +void *qemu_alloc_stack(size_t *sz) >> +{ >> + void *ptr, *guardpage; >> + size_t pagesz = getpagesize(); >> +#ifdef _SC_THREAD_STACK_MIN >> + /* avoid stacks smaller than _SC_THREAD_STACK_MIN */ >> + long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN); >> + *sz = MAX(MAX(min_stack_sz, 0), *sz); >> +#endif >> + /* adjust stack size to a multiple of the page size */ >> + *sz = ROUND_UP(*sz, pagesz); >> + /* allocate one extra page for the guard page */ >> + *sz += pagesz; >> + >> + ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, >> + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); >> + if (ptr == MAP_FAILED) { >> + abort(); >> + } >> + >> +#if defined(HOST_IA64) >> + /* separate register stack */ >> + guardpage = ptr + (((sz - pagesz) / 2) & ~pagesz); > s/sz/*sz/ > >> +#elif defined(HOST_HPPA) >> + /* stack grows up */ >> + guardpage = ptr + sz - pagesz; > Here too. I can fix both while applying the series. That would be nice, thank you. Peter
diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h index 9c7dfdf..3cfedbc 100644 --- a/include/sysemu/os-posix.h +++ b/include/sysemu/os-posix.h @@ -60,4 +60,31 @@ int qemu_utimens(const char *path, const qemu_timespec *times); bool is_daemonized(void); +/** + * qemu_alloc_stack: + * @sz: pointer to a size_t holding the requested usable stack size + * + * Allocate memory that can be used as a stack, for instance for + * coroutines. If the memory cannot be allocated, this function + * will abort (like g_malloc()). This function also inserts an + * additional guard page to catch a potential stack overflow. + * Note that the memory required for the guard page and alignment + * and minimal stack size restrictions will increase the value of sz. + * + * The allocated stack must be freed with qemu_free_stack(). + * + * Returns: pointer to (the lowest address of) the stack memory. + */ +void *qemu_alloc_stack(size_t *sz); + +/** + * qemu_free_stack: + * @stack: stack to free + * @sz: size of stack in bytes + * + * Free a stack allocated via qemu_alloc_stack(). Note that sz must + * be exactly the adjusted stack size returned by qemu_alloc_stack. + */ +void qemu_free_stack(void *stack, size_t sz); + #endif diff --git a/util/oslib-posix.c b/util/oslib-posix.c index f2d4e9e..5745229 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -499,3 +499,45 @@ pid_t qemu_fork(Error **errp) } return pid; } + +void *qemu_alloc_stack(size_t *sz) +{ + void *ptr, *guardpage; + size_t pagesz = getpagesize(); +#ifdef _SC_THREAD_STACK_MIN + /* avoid stacks smaller than _SC_THREAD_STACK_MIN */ + long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN); + *sz = MAX(MAX(min_stack_sz, 0), *sz); +#endif + /* adjust stack size to a multiple of the page size */ + *sz = ROUND_UP(*sz, pagesz); + /* allocate one extra page for the guard page */ + *sz += pagesz; + + ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (ptr == MAP_FAILED) { + abort(); + } + +#if defined(HOST_IA64) + /* separate register stack */ + guardpage = ptr + (((sz - pagesz) / 2) & ~pagesz); +#elif defined(HOST_HPPA) + /* stack grows up */ + guardpage = ptr + sz - pagesz; +#else + /* stack grows down */ + guardpage = ptr; +#endif + if (mprotect(guardpage, pagesz, PROT_NONE) != 0) { + abort(); + } + + return ptr; +} + +void qemu_free_stack(void *stack, size_t sz) +{ + munmap(stack, sz); +}
the allocated stack will be adjusted to the minimum supported stack size by the OS and rounded up to be a multiple of the system pagesize. Additionally an architecture dependent guard page is added to the stack to catch stack overflows. Signed-off-by: Peter Lieven <pl@kamp.de> --- include/sysemu/os-posix.h | 27 +++++++++++++++++++++++++++ util/oslib-posix.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 69 insertions(+)