lib/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2025-11-05 08:10:46 +03:00
Code Activity

elf: early conversion of elf p_flags to mprotect flags

Browse Source 
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>
This commit is contained in:
Cupertino Miranda
2025-08-22 11:37:00 +01:00
committed by Adhemerval Zanella
parent 921e251e8f
commit 3b2b88ccee
30 changed files with 104 additions and 102 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
include/stackinfo.h
View File

@@ -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 */