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| author | Florian Weimer <fweimer@redhat.com> | 2022-10-18 17:00:07 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2022-10-18 17:03:55 +0200 |
| commit | 88f4b6929c26f9240a4b0b7dcc62922f02544a09 (patch) | |
| tree | 72acb4a359d3ec56729a910386bd1a002bd69e3c /sysdeps/unix/sysv/linux/i386/sysdep.h | |
| parent | 246f37d6b1c4c6c0a6365df8783e62e3adf208e8 (diff) | |
| download | glibc-88f4b6929c26f9240a4b0b7dcc62922f02544a09.tar.gz glibc-88f4b6929c26f9240a4b0b7dcc62922f02544a09.tar.xz glibc-88f4b6929c26f9240a4b0b7dcc62922f02544a09.zip | |
Introduce <pointer_guard.h>, extracted from <sysdep.h>
This allows us to define a generic no-op version of PTR_MANGLE and PTR_DEMANGLE. In the future, we can use PTR_MANGLE and PTR_DEMANGLE unconditionally in C sources, avoiding an unintended loss of hardening due to missing include files or unlucky header inclusion ordering. In i386 and x86_64, we can avoid a <tls.h> dependency in the C code by using the computed constant from <tcb-offsets.h>. <sysdep.h> no longer includes these definitions, so there is no cyclic dependency anymore when computing the <tcb-offsets.h> constants. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diffstat (limited to 'sysdeps/unix/sysv/linux/i386/sysdep.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/i386/sysdep.h | 28 |
1 files changed, 0 insertions, 28 deletions
diff --git a/sysdeps/unix/sysv/linux/i386/sysdep.h b/sysdeps/unix/sysv/linux/i386/sysdep.h index 7085f7e19a..b8be668a42 100644 --- a/sysdeps/unix/sysv/linux/i386/sysdep.h +++ b/sysdeps/unix/sysv/linux/i386/sysdep.h @@ -446,34 +446,6 @@ struct libc_do_syscall_args #endif /* __ASSEMBLER__ */ - -/* Pointer mangling support. */ -#if IS_IN (rtld) -/* We cannot use the thread descriptor because in ld.so we use setjmp - earlier than the descriptor is initialized. Using a global variable - is too complicated here since we have no PC-relative addressing mode. */ -#else -# ifdef __ASSEMBLER__ -# define PTR_MANGLE(reg) xorl %gs:POINTER_GUARD, reg; \ - roll $9, reg -# define PTR_DEMANGLE(reg) rorl $9, reg; \ - xorl %gs:POINTER_GUARD, reg -# else -# define PTR_MANGLE(var) asm ("xorl %%gs:%c2, %0\n" \ - "roll $9, %0" \ - : "=r" (var) \ - : "0" (var), \ - "i" (offsetof (tcbhead_t, \ - pointer_guard))) -# define PTR_DEMANGLE(var) asm ("rorl $9, %0\n" \ - "xorl %%gs:%c2, %0" \ - : "=r" (var) \ - : "0" (var), \ - "i" (offsetof (tcbhead_t, \ - pointer_guard))) -# endif -#endif - /* Each shadow stack slot takes 4 bytes. Assuming that each stack frame takes 128 bytes, this is used to compute shadow stack size from stack size. */ |