[PATCH v4] elf: early conversion of elf p_flags to mprotect flags
Adhemerval Zanella Netto
adhemerval.zanella@linaro.org
Tue Aug 26 16:36:08 GMT 2025
On 26/08/25 13:18, Cupertino Miranda wrote:
> Hi Adhmerval,
>
> Thanks for your review.
> May you push it?
Sure, usually after Reviewed-by the patch should be ok to land.
>
> Thanks,
> Cupertino
>
> On 26-08-2025 13:51, Adhemerval Zanella Netto wrote:
>>
>>
>> On 22/08/25 07:37, Cupertino Miranda wrote:
>>> Hi everyone,
>>>
>>> Apologies for the delay reacting to the thread.
>>> It implied digging through pre-processed files to understand a minimmum
>>> set of includes that would work.
>>> Hope it makes sense.
>>>
>>> Cheers,
>>> Cupertino
>>>
>>>
>>> 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
>>>
>>> Changes from v3:
>>> - Fix includes to properly build for Hurd.
>>> 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.
>>
>> LGTM, thanks.
>>
>> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>>
>>>
>>> ---
>>> 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/mach/hurd/htl/pt-sysdep.c | 1 +
>>> 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 ++---
>>> 30 files changed, 104 insertions(+), 102 deletions(-)
>>>
>>> diff --git a/elf/Makefile b/elf/Makefile
>>> index 3a5596e2bb..5a676f858d 100644
>>> --- a/elf/Makefile
>>> +++ b/elf/Makefile
>>> @@ -2167,7 +2167,7 @@ $(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 ef4d96c053..753ce6690b 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:
>>> @@ -1541,12 +1541,12 @@ 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
>>> @@ -1556,7 +1556,7 @@ 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;
>>> }
>>> @@ -1677,8 +1677,6 @@ 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..5f2df32b46 100644
>>> --- a/include/alloca.h
>>> +++ b/include/alloca.h
>>> @@ -4,7 +4,7 @@
>>> # ifndef _ISOMAC
>>> -#include <stackinfo.h>
>>> +#include <elf.h>
>>> #undef __alloca
>>> 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/mach/hurd/htl/pt-sysdep.c b/sysdeps/mach/hurd/htl/pt-sysdep.c
>>> index 3505d31bee..735dc5b68d 100644
>>> --- a/sysdeps/mach/hurd/htl/pt-sysdep.c
>>> +++ b/sysdeps/mach/hurd/htl/pt-sysdep.c
>>> @@ -25,6 +25,7 @@
>>> #include <pt-internal.h>
>>> #include <pthreadP.h>
>>> +#include <stackinfo.h>
>>> static void
>>> reset_pthread_total (void)
>>> 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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