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x86/asm/entry/64: Change the THREAD_INFO() definition to not depend on KERNEL_STACK_OFFSET 

This changes the THREAD_INFO() definition and all its callsites
so that they do not count stack position from
(top of stack - KERNEL_STACK_OFFSET), but from top of stack.

Semi-mysterious expressions THREAD_INFO(%rsp,RIP) - "why RIP??"
are now replaced by more logical THREAD_INFO(%rsp,SIZEOF_PTREGS)
- "calculate thread_info's address using information that
rsp is SIZEOF_PTREGS bytes below top of stack".

While at it, replace "(off)-THREAD_SIZE(reg)" with equivalent
"((off)-THREAD_SIZE)(reg)". The form without parentheses
falsely looks like we invoke THREAD_SIZE() macro.

Improve comment atop THREAD_INFO macro definition.

This patch does not change generated code (verified by objdump).

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
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/1426785469-15125-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Denys Vlasenko 2015-03-19 18:17:45 +01:00 committed by Ingo Molnar
parent a76c7f4604
commit b3fe8ba320
3 changed files with 22 additions and 20 deletions
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30
arch/x86/ia32/ia32entry.S
View File

@ -127,7 +127,7 @@ ENTRY(ia32_sysenter_target)
CFI_REL_OFFSET rsp,0
pushfq_cfi
/*CFI_REL_OFFSET rflags,0*/
movl TI_sysenter_return+THREAD_INFO(%rsp,3*8-KERNEL_STACK_OFFSET),%r10d
movl TI_sysenter_return+THREAD_INFO(%rsp,3*8),%r10d
CFI_REGISTER rip,r10
pushq_cfi $__USER32_CS
/*CFI_REL_OFFSET cs,0*/
@ -159,8 +159,8 @@ ENTRY(ia32_sysenter_target)
jnz sysenter_fix_flags
sysenter_flags_fixed:
orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)
orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
CFI_REMEMBER_STATE
jnz sysenter_tracesys
cmpq $(IA32_NR_syscalls-1),%rax
@ -177,10 +177,10 @@ sysenter_dispatch:
movq %rax,RAX(%rsp)
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP)
testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jnz sysexit_audit
sysexit_from_sys_call:
andl $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)
andl $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)
/* clear IF, that popfq doesn't enable interrupts early */
andl $~0x200,EFLAGS(%rsp)
movl RIP(%rsp),%edx /* User %eip */
@ -225,7 +225,7 @@ sysexit_from_sys_call:
.endm
.macro auditsys_exit exit
testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP)
testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jnz ia32_ret_from_sys_call
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
@ -240,7 +240,7 @@ sysexit_from_sys_call:
movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl %edi,TI_flags+THREAD_INFO(%rsp,RIP)
testl %edi,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jz \exit
CLEAR_RREGS
jmp int_with_check
@ -262,7 +262,7 @@ sysenter_fix_flags:
sysenter_tracesys:
#ifdef CONFIG_AUDITSYSCALL
testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP)
testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jz sysenter_auditsys
#endif
SAVE_EXTRA_REGS
@ -346,8 +346,8 @@ ENTRY(ia32_cstar_target)
1: movl (%r8),%r9d
_ASM_EXTABLE(1b,ia32_badarg)
ASM_CLAC
orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)
orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
CFI_REMEMBER_STATE
jnz cstar_tracesys
cmpq $IA32_NR_syscalls-1,%rax
@ -364,10 +364,10 @@ cstar_dispatch:
movq %rax,RAX(%rsp)
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP)
testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jnz sysretl_audit
sysretl_from_sys_call:
andl $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)
andl $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)
RESTORE_RSI_RDI_RDX
movl RIP(%rsp),%ecx
CFI_REGISTER rip,rcx
@ -402,7 +402,7 @@ sysretl_audit:
cstar_tracesys:
#ifdef CONFIG_AUDITSYSCALL
testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP)
testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jz cstar_auditsys
#endif
xchgl %r9d,%ebp
@ -469,8 +469,8 @@ ENTRY(ia32_syscall)
this could be a problem. */
ALLOC_PT_GPREGS_ON_STACK
SAVE_C_REGS_EXCEPT_R891011
orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)
orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jnz ia32_tracesys
cmpq $(IA32_NR_syscalls-1),%rax
ja ia32_badsys

8
arch/x86/include/asm/thread_info.h
View File

@ -207,10 +207,12 @@ static inline unsigned long current_stack_pointer(void)
_ASM_SUB $(THREAD_SIZE-KERNEL_STACK_OFFSET),reg ;
/*
* Same if PER_CPU_VAR(kernel_stack) is, perhaps with some offset, already in
* a certain register (to be used in assembler memory operands).
* ASM operand which evaluates to thread_info address
* if it is known that "reg" is exactly "off" bytes below stack top.
* Example (fetch thread_info->fieldname):
* mov TI_fieldname+THREAD_INFO(reg, off),%eax
*/
#define THREAD_INFO(reg, off) KERNEL_STACK_OFFSET+(off)-THREAD_SIZE(reg)
#define THREAD_INFO(reg, off) ((off)-THREAD_SIZE)(reg)
#endif

4
arch/x86/kernel/entry_64.S
View File

@ -258,7 +258,7 @@ GLOBAL(system_call_after_swapgs)
SAVE_C_REGS_EXCEPT_RAX_RCX_R11
movq $-ENOSYS,RAX(%rsp)
CFI_REL_OFFSET rip,RIP
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jnz tracesys
system_call_fastpath:
#if __SYSCALL_MASK == ~0
@ -276,7 +276,7 @@ system_call_fastpath:
* Has incompletely filled pt_regs, iret frame is also incomplete.
*/
ret_from_sys_call:
testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP)
testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)
jnz int_ret_from_sys_call_fixup /* Go the the slow path */
LOCKDEP_SYS_EXIT