PER_CPU(old_rsp) usage is simplified - now it is used only
as temp storage, and userspace stack pointer is immediately stored
in pt_regs->sp on syscall entry, instead of being used later,
on syscall exit.
Instead of PER_CPU(old_rsp) and task->thread.usersp, C code
uses pt_regs->sp now.
FIXUP/RESTORE_TOP_OF_STACK are simplified.
Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
CC: Linus Torvalds <torva...@linux-foundation.org>
CC: Steven Rostedt <rost...@goodmis.org>
CC: Ingo Molnar <mi...@kernel.org>
CC: Borislav Petkov <b...@alien8.de>
CC: "H. Peter Anvin" <h...@zytor.com>
CC: Andy Lutomirski <l...@amacapital.net>
CC: Oleg Nesterov <o...@redhat.com>
CC: Frederic Weisbecker <fweis...@gmail.com>
CC: Alexei Starovoitov <a...@plumgrid.com>
CC: Will Drewry <w...@chromium.org>
CC: Kees Cook <keesc...@chromium.org>
CC: x...@kernel.org
CC: linux-kernel@vger.kernel.org
---
arch/x86/include/asm/compat.h | 2 +-
arch/x86/include/asm/ptrace.h | 8 ++------
arch/x86/kernel/entry_64.S | 18 +++++++-----------
arch/x86/kernel/perf_regs.c | 2 +-
arch/x86/kernel/process_64.c | 3 +--
5 files changed, 12 insertions(+), 21 deletions(-)
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 59c6c40..acdee09 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -301,7 +301,7 @@ static inline void __user
*arch_compat_alloc_user_space(long len)
sp = task_pt_regs(current)->sp;
} else {
/* -128 for the x32 ABI redzone */
- sp = this_cpu_read(old_rsp) - 128;
+ sp = task_pt_regs(current)->sp - 128;
}
return (void __user *)round_down(sp - len, 16);
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 4077d96..74bb2e0 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -145,12 +145,8 @@ static inline bool user_64bit_mode(struct pt_regs *regs)
#endif
}
-#define current_user_stack_pointer() this_cpu_read(old_rsp)
-/* ia32 vs. x32 difference */
-#define compat_user_stack_pointer() \
- (test_thread_flag(TIF_IA32) \
- ? current_pt_regs()->sp \
- : this_cpu_read(old_rsp))
+#define current_user_stack_pointer() current_pt_regs()->sp
+#define compat_user_stack_pointer() current_pt_regs()->sp
#endif
#ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 703ced0..d86788c 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -128,8 +128,6 @@ ENDPROC(native_usergs_sysret64)
* manipulation.
*/
.macro FIXUP_TOP_OF_STACK tmp offset=0
- movq PER_CPU_VAR(old_rsp),\tmp
- movq \tmp,RSP+\offset(%rsp)
movq $__USER_DS,SS+\offset(%rsp)
movq $__USER_CS,CS+\offset(%rsp)
movq RIP+\offset(%rsp),\tmp /* get rip */
@@ -139,8 +137,7 @@ ENDPROC(native_usergs_sysret64)
.endm
.macro RESTORE_TOP_OF_STACK tmp offset=0
- movq RSP+\offset(%rsp),\tmp
- movq \tmp,PER_CPU_VAR(old_rsp)
+ /* nothing to do */
.endm
/*
@@ -222,9 +219,6 @@ ENDPROC(native_usergs_sysret64)
* Interrupts are off on entry.
* Only called from user space.
*
- * XXX if we had a free scratch register we could save the RSP into the stack
frame
- * and report it properly in ps. Unfortunately we haven't.
- *
* When user can change the frames always force IRET. That is because
* it deals with uncanonical addresses better. SYSRET has trouble
* with them due to bugs in both AMD and Intel CPUs.
@@ -253,11 +247,13 @@ GLOBAL(system_call_after_swapgs)
*/
ENABLE_INTERRUPTS(CLBR_NONE)
ALLOC_PT_GPREGS_ON_STACK 8 /* +8: space for orig_ax */
+ movq %rcx,RIP(%rsp)
+ movq PER_CPU_VAR(old_rsp),%rcx
+ movq %r11,EFLAGS(%rsp)
+ movq %rcx,RSP(%rsp)
+ movq_cfi rax,ORIG_RAX
SAVE_C_REGS_EXCEPT_RAX_RCX_R11
movq $-ENOSYS,RAX(%rsp)
- movq_cfi rax,ORIG_RAX
- movq %r11,EFLAGS(%rsp)
- movq %rcx,RIP(%rsp)
CFI_REL_OFFSET rip,RIP
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)
jnz tracesys
@@ -293,7 +289,7 @@ ret_from_sys_call:
CFI_REGISTER rip,rcx
movq EFLAGS(%rsp),%r11
/*CFI_REGISTER rflags,r11*/
- movq PER_CPU_VAR(old_rsp), %rsp
+ movq RSP(%rsp),%rsp
/*
* 64bit SYSRET restores rip from rcx,
* rflags from r11 (but RF and VM bits are forced to 0),
diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
index 781861c..02a8720 100644
--- a/arch/x86/kernel/perf_regs.c
+++ b/arch/x86/kernel/perf_regs.c
@@ -177,7 +177,7 @@ void perf_get_regs_user(struct perf_regs *regs_user,
* than just blindly copying user_regs.
*/
regs_user->abi = PERF_SAMPLE_REGS_ABI_64;
- regs_user_copy->sp = this_cpu_read(old_rsp);
+ regs_user_copy->sp = user_regs->sp;
regs_user_copy->cs = __USER_CS;
regs_user_copy->ss = __USER_DS;
regs_user_copy->cx = -1; /* usually contains garbage */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 1e393d2..e8c124a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -602,6 +602,5 @@ long sys_arch_prctl(int code, unsigned long addr)
unsigned long KSTK_ESP(struct task_struct *task)
{
- return (test_tsk_thread_flag(task, TIF_IA32)) ?
- (task_pt_regs(task)->sp) : ((task)->thread.usersp);
+ return task_pt_regs(task)->sp;
}
--
1.8.1.4
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