diff options
| author | Cupertino Miranda <cupertino.miranda@oracle.com> | 2025-08-22 11:37:00 +0100 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2025-08-27 10:45:45 -0300 |
| commit | 3b2b88cceeb79f73a72367800d91599e2af4bb39 (patch) | |
| tree | a4f7c0efe8d6c2a49ac448c977a639e609c3f45c /include | |
| parent | 921e251e8f364d00fc753274095007275381ae65 (diff) | |
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>
Diffstat (limited to 'include')
| -rw-r--r-- | include/alloca.h | 2 | ||||
| -rw-r--r-- | include/stackinfo.h | 34 |
2 files changed, 35 insertions, 1 deletions
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 */ |