[PATCH v3] elf: early conversion of elf p_flags to mprotect flags
Adhemerval Zanella Netto
adhemerval.zanella@linaro.org
Wed Jul 30 13:17:57 GMT 2025
On 07/07/25 13:01, Cupertino Miranda wrote:
> Hi everyone,
>
> New version after Andreas review.
> Looking forward to your reviews.
>
> Best regards,
> Cupertino
>
> Changes from v2:
> - Cleaned style and over 80 chars lines in changed comments.
> - Removed original definition of PF_TO_PROT, it is now defined in
> stackinfo.h
> Changes from v1:
> - Changed implementation structure following Adhmerval suggestion:
> Mostly pf_to_prot function location, header includes and removed
> spurious declarations.
>
>
> This patch replaces _dl_stack_flags global variable by
> _dl_stack_prot_flags.
> The advantage is that any convertion from p_flags to final used mprotect
> flags occurs at loading of p_flags. It avoids repeated spurious
> convertions of _dl_stack_flags, for example in allocate_thread_stack.
>
> This modification was suggested in:
> https://sourceware.org/pipermail/libc-alpha/2025-March/165537.html
It broke Hurd build somehow, most likely it reorganized some includes
that implicit added stdint.h:
In file included from catgets.c:26:
catgetsinfo.h:23:3: error: unknown type name ‘uint32_t’
23 | uint32_t magic;
| ^~~~~~~~
catgetsinfo.h:19:1: note: ‘uint32_t’ is defined in header ‘<stdint.h>’; this is probably fixable by adding ‘#include <stdint.h>’
18 | #include <sys/types.h>
+++ |+#include <stdint.h>
19 |
catgetsinfo.h:24:3: error: unknown type name ‘uint32_t’
24 | uint32_t plane_size;
| ^~~~~~~~
catgetsinfo.h:24:3: note: ‘uint32_t’ is defined in header ‘<stdint.h>’; this is probably fixable by adding ‘#include <stdint.h>’
catgetsinfo.h:25:3: error: unknown type name ‘uint32_t’
25 | uint32_t plane_depth;
| ^~~~~~~~
catgetsinfo.h:25:3: note: ‘uint32_t’ is defined in header ‘<stdint.h>’; this is probably fixable by adding ‘#include <stdint.h>’
catgetsinfo.h:28:3: error: unknown type name ‘uint32_t’
28 | uint32_t name_ptr[0];
| ^~~~~~~~
catgetsinfo.h:28:3: note: ‘uint32_t’ is defined in header ‘<stdint.h>’; this is probably fixable by adding ‘#include <stdint.h>’
catgetsinfo.h:39:3: error: unknown type name ‘uint32_t’
39 | uint32_t *name_ptr;
| ^~~~~~~~
but it should easy to fix. The rest looks ok.
> ---
> elf/Makefile | 2 +-
> elf/dl-execstack-tunable.c | 2 +-
> elf/dl-load.c | 19 +++-----------
> elf/dl-support.c | 7 +++---
> elf/rtld.c | 12 ++++-----
> include/alloca.h | 2 --
> include/stackinfo.h | 34 ++++++++++++++++++++++++++
> nptl/allocatestack.c | 12 +++------
> support/support_stack_alloc.c | 9 +++----
> sysdeps/alpha/stackinfo.h | 6 ++---
> sysdeps/arm/stackinfo.h | 6 ++---
> sysdeps/generic/ldsodefs.h | 15 +-----------
> sysdeps/generic/stackinfo.h | 2 +-
> sysdeps/hppa/stackinfo.h | 6 ++---
> sysdeps/i386/stackinfo.h | 6 ++---
> sysdeps/m68k/stackinfo.h | 4 +--
> sysdeps/mach/htl/pt-stack-alloc.c | 2 +-
> sysdeps/mach/hurd/dl-execstack.c | 2 +-
> sysdeps/microblaze/stackinfo.h | 6 ++---
> sysdeps/mips/stackinfo.h | 6 ++---
> sysdeps/or1k/stackinfo.h | 6 ++---
> sysdeps/powerpc/powerpc32/stackinfo.h | 5 ++--
> sysdeps/s390/stackinfo.h | 6 ++---
> sysdeps/sh/stackinfo.h | 6 ++---
> sysdeps/sparc/stackinfo.h | 6 ++---
> sysdeps/unix/sysv/linux/dl-execstack.c | 3 ++-
> sysdeps/unix/sysv/linux/machine-sp.h | 2 ++
> sysdeps/unix/sysv/linux/spawni.c | 5 +---
> sysdeps/x86_64/stackinfo.h | 6 ++---
> 29 files changed, 102 insertions(+), 103 deletions(-)
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 44b9f192f2..23294a62c3 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -2160,7 +2160,7 @@ $(objpfx)execstack-default: $(first-word $(wildcard $(sysdirs:%=%/stackinfo.h)))
> $(make-target-directory)
> { echo '#include <elf.h>'; \
> echo '#include <stackinfo.h>'; \
> - echo '#if (DEFAULT_STACK_PERMS & PF_X) == 0'; \
> + echo '#if (DEFAULT_STACK_PROT_PERMS & PROT_EXEC) == 0'; \
> echo '@@@execstack-no@@@'; \
> echo '#else'; \
> echo '@@@execstack-yes@@@'; \
> diff --git a/elf/dl-execstack-tunable.c b/elf/dl-execstack-tunable.c
> index e3b638aeaa..b2511ea031 100644
> --- a/elf/dl-execstack-tunable.c
> +++ b/elf/dl-execstack-tunable.c
> @@ -25,7 +25,7 @@ _dl_handle_execstack_tunable (void)
> switch (TUNABLE_GET (glibc, rtld, execstack, int32_t, NULL))
> {
> case stack_tunable_mode_disable:
> - if ((__glibc_unlikely (GL(dl_stack_flags)) & PF_X))
> + if ((__glibc_unlikely (GL(dl_stack_prot_flags)) & PROT_EXEC))
> _dl_fatal_printf (
> "Fatal glibc error: executable stack is not allowed\n");
> break;
> diff --git a/elf/dl-load.c b/elf/dl-load.c
> index 00b9da9ec7..891b44966c 100644
> --- a/elf/dl-load.c
> +++ b/elf/dl-load.c
> @@ -1095,7 +1095,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
> /* On most platforms presume that PT_GNU_STACK is absent and the stack is
> * executable. Other platforms default to a nonexecutable stack and don't
> * need PT_GNU_STACK to do so. */
> - unsigned int stack_flags = DEFAULT_STACK_PERMS;
> + unsigned int stack_flags = DEFAULT_STACK_PROT_PERMS;
>
> {
> /* Scan the program header table, collecting its load commands. */
> @@ -1170,18 +1170,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
> DIAG_POP_NEEDS_COMMENT;
>
> /* Optimize a common case. */
> -#if (PF_R | PF_W | PF_X) == 7 && (PROT_READ | PROT_WRITE | PROT_EXEC) == 7
> - c->prot = (PF_TO_PROT
> - >> ((ph->p_flags & (PF_R | PF_W | PF_X)) * 4)) & 0xf;
> -#else
> - c->prot = 0;
> - if (ph->p_flags & PF_R)
> - c->prot |= PROT_READ;
> - if (ph->p_flags & PF_W)
> - c->prot |= PROT_WRITE;
> - if (ph->p_flags & PF_X)
> - c->prot |= PROT_EXEC;
> -#endif
> + c->prot = pf_to_prot (ph->p_flags);
> break;
>
> case PT_TLS:
> @@ -1218,7 +1207,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
> break;
>
> case PT_GNU_STACK:
> - stack_flags = ph->p_flags;
> + stack_flags = pf_to_prot (ph->p_flags);
> break;
>
> case PT_GNU_RELRO:
> @@ -1318,7 +1307,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
> /* Adjust the PT_PHDR value by the runtime load address. */
> l->l_phdr = (ElfW(Phdr) *) ((ElfW(Addr)) l->l_phdr + l->l_addr);
>
> - if (__glibc_unlikely ((stack_flags &~ GL(dl_stack_flags)) & PF_X))
> + if (__glibc_unlikely ((stack_flags &~ GL(dl_stack_prot_flags)) & PROT_EXEC))
> {
> /* The stack is presently not executable, but this module
> requires that it be executable. Only tries to change the
> diff --git a/elf/dl-support.c b/elf/dl-support.c
> index 7b2a1c35d5..bbef3ab6b6 100644
> --- a/elf/dl-support.c
> +++ b/elf/dl-support.c
> @@ -166,9 +166,8 @@ enum dso_sort_algorithm _dl_dso_sort_algo;
> /* The value of the FPU control word the kernel will preset in hardware. */
> fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
>
> -/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
> - * executable but this isn't true for all platforms. */
> -ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
> +/* Required flags used for stack allocation. */
> +int _dl_stack_prot_flags = DEFAULT_STACK_PROT_PERMS;
>
> #if PTHREAD_IN_LIBC
> list_t _dl_stack_used;
> @@ -322,7 +321,7 @@ _dl_non_dynamic_init (void)
> {
> /* Check if the stack is nonexecutable. */
> case PT_GNU_STACK:
> - _dl_stack_flags = ph->p_flags;
> + _dl_stack_prot_flags = pf_to_prot (ph->p_flags);
> break;
>
> case PT_GNU_RELRO:
> diff --git a/elf/rtld.c b/elf/rtld.c
> index f889f01b4a..2e2c1f3bd0 100644
> --- a/elf/rtld.c
> +++ b/elf/rtld.c
> @@ -322,7 +322,7 @@ struct rtld_global _rtld_global =
> #include <dl-procruntime.c>
> /* Generally the default presumption without further information is an
> * executable stack but this is not true for all platforms. */
> - ._dl_stack_flags = DEFAULT_STACK_PERMS,
> + ._dl_stack_prot_flags = DEFAULT_STACK_PROT_PERMS,
> #ifdef _LIBC_REENTRANT
> ._dl_load_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER,
> ._dl_load_write_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER,
> @@ -1197,7 +1197,7 @@ rtld_setup_main_map (struct link_map *main_map)
> break;
>
> case PT_GNU_STACK:
> - GL(dl_stack_flags) = ph->p_flags;
> + GL(dl_stack_prot_flags) = pf_to_prot (ph->p_flags);
> break;
>
> case PT_GNU_RELRO:
> @@ -1487,12 +1487,12 @@ dl_main (const ElfW(Phdr) *phdr,
> --_dl_argc;
> ++_dl_argv;
>
> - /* The initialization of _dl_stack_flags done below assumes the
> + /* The initialization of dl_stack_prot_flags done below assumes the
> executable's PT_GNU_STACK may have been honored by the kernel, and
> so a PT_GNU_STACK with PF_X set means the stack started out with
> execute permission. However, this is not really true if the
> dynamic linker is the executable the kernel loaded. For this
> - case, we must reinitialize _dl_stack_flags to match the dynamic
> + case, we must reinitialize dl_stack_prot_flags to match the dynamic
> linker itself. If the dynamic linker was built with a
> PT_GNU_STACK, then the kernel may have loaded us with a
> nonexecutable stack that we will have to make executable when we
> @@ -1502,7 +1502,7 @@ dl_main (const ElfW(Phdr) *phdr,
> for (const ElfW(Phdr) *ph = phdr; ph < &phdr[phnum]; ++ph)
> if (ph->p_type == PT_GNU_STACK)
> {
> - GL(dl_stack_flags) = ph->p_flags;
> + GL(dl_stack_prot_flags) = pf_to_prot (ph->p_flags);
> break;
> }
>
> @@ -1623,8 +1623,6 @@ dl_main (const ElfW(Phdr) *phdr,
>
> bool has_interp = rtld_setup_main_map (main_map);
>
> - /* Handle this after PT_GNU_STACK parse, because it updates dl_stack_flags
> - if required. */
> _dl_handle_execstack_tunable ();
>
> /* If the current libname is different from the SONAME, add the
> diff --git a/include/alloca.h b/include/alloca.h
> index c0b8395443..1bd3af3e27 100644
> --- a/include/alloca.h
> +++ b/include/alloca.h
> @@ -4,8 +4,6 @@
>
> # ifndef _ISOMAC
>
> -#include <stackinfo.h>
> -
> #undef __alloca
>
> /* Now define the internal interfaces. */
> diff --git a/include/stackinfo.h b/include/stackinfo.h
> index 3c1541b42d..3cf36c9b1d 100644
> --- a/include/stackinfo.h
> +++ b/include/stackinfo.h
> @@ -39,4 +39,38 @@
> # error "stackinfo.h must define _STACK_GROWS_UP or _STACK_GROWS_DOWN!"
> #endif
>
> +#include <sys/mman.h>
> +#include <link.h>
> +
> +/* ELF uses the PF_x macros to specify the segment permissions, mmap
> + uses PROT_xxx. In most cases the three macros have the values 1, 2,
> + and 4 but not in a matching order. The following macros allows
> + converting from the PF_x values to PROT_xxx values. */
> +#define PF_TO_PROT \
> + ((PROT_READ << (PF_R * 4)) \
> + | (PROT_WRITE << (PF_W * 4)) \
> + | (PROT_EXEC << (PF_X * 4)) \
> + | ((PROT_READ | PROT_WRITE) << ((PF_R | PF_W) * 4)) \
> + | ((PROT_READ | PROT_EXEC) << ((PF_R | PF_X) * 4)) \
> + | ((PROT_WRITE | PROT_EXEC) << (PF_W | PF_X) * 4) \
> + | ((PROT_READ | PROT_WRITE | PROT_EXEC) << ((PF_R | PF_W | PF_X) * 4)))
> +
> +static inline int
> +pf_to_prot (ElfW(Word) value)
> +{
> +#if (PF_R | PF_W | PF_X) == 7 && (PROT_READ | PROT_WRITE | PROT_EXEC) == 7
> + return (PF_TO_PROT >> ((value & (PF_R | PF_W | PF_X)) * 4)) & 0xf;
> +#else
> + ElfW(Word) ret = 0;
> + if (value & PF_R)
> + ret |= PROT_READ;
> + if (value & PF_W)
> + ret |= PROT_WRITE;
> + if (value & PF_X)
> + ret |= PROT_EXEC;
> + return ret;
> +#endif
> +
> +}
> +
> #endif /* include/stackinfo.h */
> diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
> index 800ca89720..4c2aacdd10 100644
> --- a/nptl/allocatestack.c
> +++ b/nptl/allocatestack.c
> @@ -150,17 +150,11 @@ get_cached_stack (size_t *sizep, void **memp)
> and fallback to ALLOCATE_GUARD_PROT_NONE if the madvise call fails. */
> static int allocate_stack_mode = ALLOCATE_GUARD_MADV_GUARD;
>
> -static inline int stack_prot (void)
> -{
> - return (PROT_READ | PROT_WRITE
> - | ((GL(dl_stack_flags) & PF_X) ? PROT_EXEC : 0));
> -}
> -
> static void *
> allocate_thread_stack (size_t size, size_t guardsize)
> {
> /* MADV_ADVISE_GUARD does not require an additional PROT_NONE mapping. */
> - int prot = stack_prot ();
> + int prot = GL(dl_stack_prot_flags);
>
> if (atomic_load_relaxed (&allocate_stack_mode) == ALLOCATE_GUARD_PROT_NONE)
> /* If a guard page is required, avoid committing memory by first allocate
> @@ -216,7 +210,7 @@ setup_stack_prot (char *mem, size_t size, struct pthread *pd,
> }
> else
> {
> - const int prot = stack_prot ();
> + const int prot = GL(dl_stack_prot_flags);
> char *guardend = guard + guardsize;
> #if _STACK_GROWS_DOWN
> /* As defined at guard_position, for architectures with downward stack
> @@ -294,7 +288,7 @@ adjust_stack_prot (char *mem, size_t size, const struct pthread *pd,
> }
> else if (pd->stack_mode == ALLOCATE_GUARD_PROT_NONE)
> {
> - const int prot = stack_prot ();
> + const int prot = GL(dl_stack_prot_flags);
> #if _STACK_GROWS_DOWN
> return __mprotect (mem + guardsize, slacksize, prot) == 0;
> #else
> diff --git a/support/support_stack_alloc.c b/support/support_stack_alloc.c
> index 5e576bea74..132e7b4f70 100644
> --- a/support/support_stack_alloc.c
> +++ b/support/support_stack_alloc.c
> @@ -64,11 +64,10 @@ support_stack_alloc (size_t size)
> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE|MAP_STACK,
> -1);
> /* Some architecture still requires executable stack for the signal return
> - trampoline, although PF_X could be overridden if PT_GNU_STACK is present.
> - However since glibc does not export such information with a proper ABI,
> - it uses the historical permissions. */
> - int prot = PROT_READ | PROT_WRITE
> - | (DEFAULT_STACK_PERMS & PF_X ? PROT_EXEC : 0);
> + trampoline, although PROT_EXEC could be overridden if PT_GNU_STACK is
> + present. However since glibc does not export such information with a
> + proper ABI, it uses the historical permissions. */
> + int prot = DEFAULT_STACK_PROT_PERMS;
> xmprotect (alloc_base + guardsize, stacksize, prot);
> memset (alloc_base + guardsize, 0xA5, stacksize);
> return (struct support_stack) { alloc_base + guardsize, stacksize, guardsize };
> diff --git a/sysdeps/alpha/stackinfo.h b/sysdeps/alpha/stackinfo.h
> index a469964c10..d69647756b 100644
> --- a/sysdeps/alpha/stackinfo.h
> +++ b/sysdeps/alpha/stackinfo.h
> @@ -26,8 +26,8 @@
> /* On Alpha the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h */
> diff --git a/sysdeps/arm/stackinfo.h b/sysdeps/arm/stackinfo.h
> index 3068352eab..30608f7062 100644
> --- a/sysdeps/arm/stackinfo.h
> +++ b/sysdeps/arm/stackinfo.h
> @@ -26,8 +26,8 @@
> /* On Arm the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h */
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 74025f1f93..31e9a6b600 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -171,19 +171,6 @@ dl_symbol_visibility_binds_local_p (const ElfW(Sym) *sym)
> # define ELF_RTYPE_CLASS_COPY 0
> #endif
>
> -/* ELF uses the PF_x macros to specify the segment permissions, mmap
> - uses PROT_xxx. In most cases the three macros have the values 1, 2,
> - and 3 but not in a matching order. The following macros allows
> - converting from the PF_x values to PROT_xxx values. */
> -#define PF_TO_PROT \
> - ((PROT_READ << (PF_R * 4)) \
> - | (PROT_WRITE << (PF_W * 4)) \
> - | (PROT_EXEC << (PF_X * 4)) \
> - | ((PROT_READ | PROT_WRITE) << ((PF_R | PF_W) * 4)) \
> - | ((PROT_READ | PROT_EXEC) << ((PF_R | PF_X) * 4)) \
> - | ((PROT_WRITE | PROT_EXEC) << (PF_W | PF_X) * 4) \
> - | ((PROT_READ | PROT_WRITE | PROT_EXEC) << ((PF_R | PF_W | PF_X) * 4)))
> -
> /* The filename itself, or the main program name, if available. */
> #define DSO_FILENAME(name) ((name)[0] ? (name) \
> : (rtld_progname ?: "<main program>"))
> @@ -416,7 +403,7 @@ struct rtld_global
> #include <dl-procruntime.c>
>
> /* Prevailing state of the stack, PF_X indicating it's executable. */
> - EXTERN ElfW(Word) _dl_stack_flags;
> + EXTERN int _dl_stack_prot_flags;
>
> /* Flag signalling whether there are gaps in the module ID allocation. */
> EXTERN bool _dl_tls_dtv_gaps;
> diff --git a/sysdeps/generic/stackinfo.h b/sysdeps/generic/stackinfo.h
> index 8abbb3dff7..ab3e72e5c2 100644
> --- a/sysdeps/generic/stackinfo.h
> +++ b/sysdeps/generic/stackinfo.h
> @@ -24,6 +24,6 @@
> #include <elf.h>
>
> #define _STACK_GROWS_DOWN 1
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W)
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE)
>
> #endif
> diff --git a/sysdeps/hppa/stackinfo.h b/sysdeps/hppa/stackinfo.h
> index 53bb11fde0..22920d20a9 100644
> --- a/sysdeps/hppa/stackinfo.h
> +++ b/sysdeps/hppa/stackinfo.h
> @@ -23,9 +23,9 @@
>
> #include <elf.h>
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> /* On PA the stack grows up. */
> #define _STACK_GROWS_UP 1
> diff --git a/sysdeps/i386/stackinfo.h b/sysdeps/i386/stackinfo.h
> index 74e82278d3..8d7a46c405 100644
> --- a/sysdeps/i386/stackinfo.h
> +++ b/sysdeps/i386/stackinfo.h
> @@ -26,9 +26,9 @@
> /* On x86 the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> /* Access to the stack pointer. The macros are used in alloca_account
> for which they need to act as barriers as well, hence the additional
> diff --git a/sysdeps/m68k/stackinfo.h b/sysdeps/m68k/stackinfo.h
> index 7a757df147..74c0af5563 100644
> --- a/sysdeps/m68k/stackinfo.h
> +++ b/sysdeps/m68k/stackinfo.h
> @@ -26,9 +26,9 @@
> /* On m68k the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> is present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> /* Access to the stack pointer. */
> #define stackinfo_get_sp() \
> diff --git a/sysdeps/mach/htl/pt-stack-alloc.c b/sysdeps/mach/htl/pt-stack-alloc.c
> index 3e196f8ca7..42762bc0ad 100644
> --- a/sysdeps/mach/htl/pt-stack-alloc.c
> +++ b/sysdeps/mach/htl/pt-stack-alloc.c
> @@ -33,7 +33,7 @@ __pthread_stack_alloc (void **stackaddr, size_t stacksize)
> error_t err;
> vm_prot_t prot = VM_PROT_READ | VM_PROT_WRITE;
>
> - if (GL(dl_stack_flags) & PF_X)
> + if (GL(dl_stack_prot_flags) & PROT_EXEC)
> prot |= VM_PROT_EXECUTE;
>
> err = __vm_map (__mach_task_self (), (vm_offset_t *) stackaddr,
> diff --git a/sysdeps/mach/hurd/dl-execstack.c b/sysdeps/mach/hurd/dl-execstack.c
> index dc4719bd38..9e69169367 100644
> --- a/sysdeps/mach/hurd/dl-execstack.c
> +++ b/sysdeps/mach/hurd/dl-execstack.c
> @@ -38,7 +38,7 @@ _dl_make_stack_executable (const void *stack_endp)
> return errno;
>
> /* Remember that we changed the permission. */
> - GL(dl_stack_flags) |= PF_X;
> + GL(dl_stack_prot_flags) |= PROT_EXEC;
>
> return 0;
> #else
> diff --git a/sysdeps/microblaze/stackinfo.h b/sysdeps/microblaze/stackinfo.h
> index 8960bd3d25..51d40a7732 100644
> --- a/sysdeps/microblaze/stackinfo.h
> +++ b/sysdeps/microblaze/stackinfo.h
> @@ -27,8 +27,8 @@
> /* On MicroBlaze the stack grows down. */
> # define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -# define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h. */
> diff --git a/sysdeps/mips/stackinfo.h b/sysdeps/mips/stackinfo.h
> index 6cce9386d6..107a8ea7c9 100644
> --- a/sysdeps/mips/stackinfo.h
> +++ b/sysdeps/mips/stackinfo.h
> @@ -26,8 +26,8 @@
> /* On MIPS the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h */
> diff --git a/sysdeps/or1k/stackinfo.h b/sysdeps/or1k/stackinfo.h
> index 39cf5c2456..10a56c57f7 100644
> --- a/sysdeps/or1k/stackinfo.h
> +++ b/sysdeps/or1k/stackinfo.h
> @@ -27,8 +27,8 @@
> /* On or1k the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R | PF_W | PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h */
> diff --git a/sysdeps/powerpc/powerpc32/stackinfo.h b/sysdeps/powerpc/powerpc32/stackinfo.h
> index 31cba55805..327e614445 100644
> --- a/sysdeps/powerpc/powerpc32/stackinfo.h
> +++ b/sysdeps/powerpc/powerpc32/stackinfo.h
> @@ -26,7 +26,8 @@
> /* On PPC the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* PF_X can be overridden if PT_GNU_STACK is present but is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* PROT_EXEC can be overridden if PT_GNU_STACK is present but is presumed
> + absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h */
> diff --git a/sysdeps/s390/stackinfo.h b/sysdeps/s390/stackinfo.h
> index 657ab3487f..9be764495a 100644
> --- a/sysdeps/s390/stackinfo.h
> +++ b/sysdeps/s390/stackinfo.h
> @@ -26,8 +26,8 @@
> /* On s390 the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h */
> diff --git a/sysdeps/sh/stackinfo.h b/sysdeps/sh/stackinfo.h
> index 8f7bf163be..e502993d24 100644
> --- a/sysdeps/sh/stackinfo.h
> +++ b/sysdeps/sh/stackinfo.h
> @@ -26,8 +26,8 @@
> /* On SH the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h */
> diff --git a/sysdeps/sparc/stackinfo.h b/sysdeps/sparc/stackinfo.h
> index 23a74ed7fe..a4a0eb15c9 100644
> --- a/sysdeps/sparc/stackinfo.h
> +++ b/sysdeps/sparc/stackinfo.h
> @@ -26,8 +26,8 @@
> /* On sparc the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> #endif /* stackinfo.h */
> diff --git a/sysdeps/unix/sysv/linux/dl-execstack.c b/sysdeps/unix/sysv/linux/dl-execstack.c
> index 6db9601656..a59bd5632a 100644
> --- a/sysdeps/unix/sysv/linux/dl-execstack.c
> +++ b/sysdeps/unix/sysv/linux/dl-execstack.c
> @@ -17,6 +17,7 @@
> <https://www.gnu.org/licenses/>. */
>
> #include <ldsodefs.h>
> +#include <stackinfo.h>
>
> int
> _dl_make_stack_executable (const void *stack_endp)
> @@ -36,7 +37,7 @@ _dl_make_stack_executable (const void *stack_endp)
> return errno;
>
> /* Remember that we changed the permission. */
> - GL(dl_stack_flags) |= PF_X;
> + GL(dl_stack_prot_flags) |= PROT_EXEC;
>
> return 0;
> }
> diff --git a/sysdeps/unix/sysv/linux/machine-sp.h b/sysdeps/unix/sysv/linux/machine-sp.h
> index 6ab3ca6d50..bda90fe801 100644
> --- a/sysdeps/unix/sysv/linux/machine-sp.h
> +++ b/sysdeps/unix/sysv/linux/machine-sp.h
> @@ -19,6 +19,8 @@
> #ifndef _MACHINE_SP_H
> #define _MACHINE_SP_H
>
> +#include <stackinfo.h>
> +
> /* Return the current stack pointer. */
> static inline uintptr_t
> __thread_stack_pointer (void)
> diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c
> index eca1a84254..bc8476ff11 100644
> --- a/sysdeps/unix/sysv/linux/spawni.c
> +++ b/sysdeps/unix/sysv/linux/spawni.c
> @@ -348,9 +348,6 @@ __spawnix (int *pid, const char *file,
> return errno;
> }
>
> - int prot = (PROT_READ | PROT_WRITE
> - | ((GL (dl_stack_flags) & PF_X) ? PROT_EXEC : 0));
> -
> /* Add a slack area for child's stack. */
> size_t argv_size = (argc * sizeof (void *)) + 512;
> /* We need at least a few pages in case the compiler's stack checking is
> @@ -361,7 +358,7 @@ __spawnix (int *pid, const char *file,
> where it might use about 1k extra stack space). */
> argv_size += (32 * 1024);
> size_t stack_size = ALIGN_UP (argv_size, GLRO(dl_pagesize));
> - void *stack = __mmap (NULL, stack_size, prot,
> + void *stack = __mmap (NULL, stack_size, GL (dl_stack_prot_flags),
> MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
> if (__glibc_unlikely (stack == MAP_FAILED))
> return errno;
> diff --git a/sysdeps/x86_64/stackinfo.h b/sysdeps/x86_64/stackinfo.h
> index 416d687869..0e88e6d94e 100644
> --- a/sysdeps/x86_64/stackinfo.h
> +++ b/sysdeps/x86_64/stackinfo.h
> @@ -32,9 +32,9 @@
> /* On x86_64 the stack grows down. */
> #define _STACK_GROWS_DOWN 1
>
> -/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
> - * present, but it is presumed absent. */
> -#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
> +/* Default to an executable stack. PROT_EXEC can be overridden if PT_GNU_STACK
> + * is present, but it is presumed absent. */
> +#define DEFAULT_STACK_PROT_PERMS (PROT_READ|PROT_WRITE|PROT_EXEC)
>
> /* Access to the stack pointer. The macros are used in alloca_account
> for which they need to act as barriers as well, hence the additional
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