elf: early conversion of elf p_flags to mprotect flags

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

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

21 files changed, 48 insertions, 59 deletions

diff --git a/sysdeps/alpha/stackinfo.h b/sysdeps/alpha/stackinfo.h
index a469964..d696477 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 3068352..30608f7 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 74025f1..31e9a6b 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 8abbb3d..ab3e72e 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 53bb11f..22920d2 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 74e8227..8d7a46c 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 7a757df..74c0af5 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 64cc186..d9f3e24 100644
--- a/sysdeps/mach/htl/pt-stack-alloc.c
+++ b/sysdeps/mach/htl/pt-stack-alloc.c
@@ -34,7 +34,7 @@ __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 dc4719b..9e69169 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 3505d31..735dc5b 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 8960bd3..51d40a7 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 6cce938..107a8ea 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 39cf5c2..10a56c5 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 31cba55..327e614 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 657ab34..9be7644 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 8f7bf16..e502993 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 23a74ed..a4a0eb1 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 6db9601..a59bd56 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 6ab3ca6..bda90fe 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 eca1a84..bc8476f 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 416d687..0e88e6d 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