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ARM: Don't apply pointer encryption to the frame pointer

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The frame pointer register is rarely used for that purpose on ARM and
applications that look at the contents of the jmp_buf may be relying
on reading an unencrypted value. For example, Ruby uses the contents
of jmp_buf to find the root set for garbage collection so relies on
this pointer value being unencrypted. Without this patch the Ruby
testsuite fails with a segmentation fault.

ports/ChangeLog.arm:

2013-01-14  Will Newton  <will.newton@linaro.org>

	* sysdeps/arm/__longjmp.S: Don't apply pointer encryption
	to fp register.
	* sysdeps/arm/setjmp.S: Likewise.
	* sysdeps/arm/include/bits/setjmp.h (JMP_BUF_REGLIST): Add
	fp to register list, remove a4.
	* sysdeps/unix/sysv/linux/arm/sysdep.h (PTR_MANGLE_LOAD):
	New macro.
This commit is contained in:
Will Newton 2013-12-10 16:26:38 +00:00
parent 497b1e69f9
commit 2f10c4d690
5 changed files with 20 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
ports/ChangeLog.arm
View File

@ -1,3 +1,13 @@
2014-01-14 Will Newton <will.newton@linaro.org>
* sysdeps/arm/__longjmp.S: Don't apply pointer encryption
to fp register.
* sysdeps/arm/setjmp.S: Likewise.
* sysdeps/arm/include/bits/setjmp.h (JMP_BUF_REGLIST): Add
fp to register list, remove a4.
* sysdeps/unix/sysv/linux/arm/sysdep.h (PTR_MANGLE_LOAD):
New macro.
2014-01-10 Roland McGrath <roland@hack.frob.com>
* sysdeps/arm/arm-mcount.S:

4
ports/sysdeps/arm/__longjmp.S
View File

@ -41,14 +41,12 @@ ENTRY (__longjmp)
sfi_sp sfi_breg ip, \
ldmia \B!, JMP_BUF_REGLIST
#ifdef PTR_DEMANGLE
PTR_DEMANGLE (fp, a4, a3, a2)
ldr a4, [ip], #4
PTR_DEMANGLE2 (a4, a4, a3)
PTR_DEMANGLE (a4, a4, a3, a2)
mov sp, a4
ldr a4, [ip], #4
PTR_DEMANGLE2 (lr, a4, a3)
#else
mov fp, a4
ldr sp, [ip], #4
ldr lr, [ip], #4
#endif

5
ports/sysdeps/arm/include/bits/setjmp.h
View File

@ -26,9 +26,8 @@
#ifndef _ISOMAC
/* Register list for a ldm/stm instruction to load/store
the general registers from a __jmp_buf. The a4 register
contains fp at this point. */
# define JMP_BUF_REGLIST {a4, v1-v6, sl}
the general registers from a __jmp_buf. */
# define JMP_BUF_REGLIST {v1-v6, sl, fp}
/* Index of __jmp_buf where the sp register resides. */
# define __JMP_BUF_SP 8

4
ports/sysdeps/arm/setjmp.S
View File

@ -23,9 +23,7 @@
ENTRY (__sigsetjmp)
#ifdef PTR_MANGLE
PTR_MANGLE (a4, fp, a3, ip)
#else
mov a4, fp
PTR_MANGLE_LOAD (a3, ip)
#endif
mov ip, r0

8
ports/sysdeps/unix/sysv/linux/arm/sysdep.h
View File

@ -439,8 +439,10 @@ __local_syscall_error: \
#if (defined NOT_IN_libc && defined IS_IN_rtld) || \
(!defined SHARED && (!defined NOT_IN_libc || defined IS_IN_libpthread))
# ifdef __ASSEMBLER__
# define PTR_MANGLE_LOAD(guard, tmp) \
LDST_PCREL(ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard_local));
# define PTR_MANGLE(dst, src, guard, tmp) \
LDST_PCREL(ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard_local)); \
PTR_MANGLE_LOAD(guard, tmp); \
PTR_MANGLE2(dst, src, guard)
/* Use PTR_MANGLE2 for efficiency if guard is already loaded. */
# define PTR_MANGLE2(dst, src, guard) \
@ -457,8 +459,10 @@ extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
# endif
#else
# ifdef __ASSEMBLER__
# define PTR_MANGLE_LOAD(guard, tmp) \
LDST_GLOBAL(ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard));
# define PTR_MANGLE(dst, src, guard, tmp) \
LDST_GLOBAL(ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard)); \
PTR_MANGLE_LOAD(guard, tmp); \
PTR_MANGLE2(dst, src, guard)
/* Use PTR_MANGLE2 for efficiency if guard is already loaded. */
# define PTR_MANGLE2(dst, src, guard) \