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| author | Denys Vlasenko <dvlasenk@redhat.com> | 2015-04-04 20:55:19 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-04-06 09:24:08 +0200 |
| commit | fc3e958a2b552fe6210e6de3bebb4348156a0b5f (patch) | |
| tree | faa91925b07208febff9ad6dcda4dac17f9c9c59 /arch/x86/include | |
| parent | 6a3713f001b3b53587e411ab0d3036ae9b0fb93b (diff) | |
| download | linux-fc3e958a2b552fe6210e6de3bebb4348156a0b5f.tar.bz2 | |
x86/asm/entry: Clear EXTRA_REGS for all executable formats
On failure, sys_execve() does not clobber EXTRA_REGS, so we can
just return to userpsace without saving/restoring them.
On success, ELF_PLAT_INIT() in sys_execve() clears all these
registers.
On other executable formats:
- binfmt_flat.c has similar FLAT_PLAT_INIT, but x86 (and everyone
else except sh) doesn't define it.
- binfmt_elf_fdpic.c has ELF_FDPIC_PLAT_INIT, but x86 (and most
others) doesn't define it.
- There are no such hooks in binfmt_aout.c et al. We inherit
EXTRA_REGS from the prior executable.
This inconsistency was not intended.
This change removes SAVE/RESTORE_EXTRA_REGS in stub_execve,
removes register clearing in ELF_PLAT_INIT(),
and instead simply clears them on success in stub_execve.
Run-tested.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1428173719-7637-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/calling.h | 9 | ||||
| -rw-r--r-- | arch/x86/include/asm/elf.h | 7 |
2 files changed, 13 insertions, 3 deletions
diff --git a/arch/x86/include/asm/calling.h b/arch/x86/include/asm/calling.h index 4b5f7bf2b780..1c8b50edb2db 100644 --- a/arch/x86/include/asm/calling.h +++ b/arch/x86/include/asm/calling.h @@ -151,6 +151,15 @@ For 32-bit we have the following conventions - kernel is built with movq_cfi_restore 5*8+\offset, rbx .endm + .macro ZERO_EXTRA_REGS + xorl %r15d, %r15d + xorl %r14d, %r14d + xorl %r13d, %r13d + xorl %r12d, %r12d + xorl %ebp, %ebp + xorl %ebx, %ebx + .endm + .macro RESTORE_C_REGS_HELPER rstor_rax=1, rstor_rcx=1, rstor_r11=1, rstor_r8910=1, rstor_rdx=1 .if \rstor_r11 movq_cfi_restore 6*8, r11 diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index ca3347a9dab5..3563107b5060 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -171,10 +171,11 @@ do { \ static inline void elf_common_init(struct thread_struct *t, struct pt_regs *regs, const u16 ds) { - regs->ax = regs->bx = regs->cx = regs->dx = 0; - regs->si = regs->di = regs->bp = 0; + /* Commented-out registers are cleared in stub_execve */ + /*regs->ax = regs->bx =*/ regs->cx = regs->dx = 0; + regs->si = regs->di /*= regs->bp*/ = 0; regs->r8 = regs->r9 = regs->r10 = regs->r11 = 0; - regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0; + /*regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;*/ t->fs = t->gs = 0; t->fsindex = t->gsindex = 0; t->ds = t->es = ds; |