[PATCH v4] elf: early conversion of elf p_flags to mprotect flags
Cupertino Miranda
cupertino.miranda@oracle.com
Tue Aug 26 16:18:24 GMT 2025
Hi Adhmerval,
Thanks for your review.
May you push it?
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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