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>

1 files changed, 15 insertions, 15 deletions

diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index ad9efef65a6b..50190e15c1b6 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -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