From 9aa3113a42d94d7bbf9bb4d50ef0d23b95e66123 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Wed, 25 Jul 2018 04:39:26 -0700 Subject: x86: Rename __glibc_reserved2 to ssp_base in tcbhead_t This will be used to record the current shadow stack base for shadow stack switching by getcontext, makecontext, setcontext and swapcontext. If the target shadow stack base is the same as the current shadow stack base, we unwind the shadow stack. Otherwise it is a stack switch and we look for a restore token to restore the target shadow stack. * sysdeps/i386/nptl/tcb-offsets.sym (SSP_BASE_OFFSET): New. * sysdeps/i386/nptl/tls.h (tcbhead_t): Replace __glibc_reserved2 with ssp_base. * sysdeps/x86_64/nptl/tcb-offsets.sym (SSP_BASE_OFFSET): New. * sysdeps/x86_64/nptl/tls.h (tcbhead_t): Replace __glibc_reserved2 with ssp_base. --- sysdeps/i386/nptl/tcb-offsets.sym | 1 + sysdeps/i386/nptl/tls.h | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) (limited to 'sysdeps/i386') diff --git a/sysdeps/i386/nptl/tcb-offsets.sym b/sysdeps/i386/nptl/tcb-offsets.sym index fbac241c45..2ec9e787c1 100644 --- a/sysdeps/i386/nptl/tcb-offsets.sym +++ b/sysdeps/i386/nptl/tcb-offsets.sym @@ -13,3 +13,4 @@ CLEANUP_PREV offsetof (struct _pthread_cleanup_buffer, __prev) MUTEX_FUTEX offsetof (pthread_mutex_t, __data.__lock) POINTER_GUARD offsetof (tcbhead_t, pointer_guard) FEATURE_1_OFFSET offsetof (tcbhead_t, feature_1) +SSP_BASE_OFFSET offsetof (tcbhead_t, ssp_base) diff --git a/sysdeps/i386/nptl/tls.h b/sysdeps/i386/nptl/tls.h index 21e23cd809..12285d3217 100644 --- a/sysdeps/i386/nptl/tls.h +++ b/sysdeps/i386/nptl/tls.h @@ -49,7 +49,8 @@ typedef struct void *__private_tm[3]; /* GCC split stack support. */ void *__private_ss; - void *__glibc_reserved2; + /* The lowest address of shadow stack, */ + unsigned long ssp_base; } tcbhead_t; /* morestack.S in libgcc uses offset 0x30 to access __private_ss, */ -- cgit 1.4.1