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Diffstat (limited to 'arch/x86/entry/entry_64.S')
-rw-r--r--arch/x86/entry/entry_64.S63
1 files changed, 51 insertions, 12 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 4300ba49b5ee..9953d966d124 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -85,7 +85,7 @@
*/
SYM_CODE_START(entry_SYSCALL_64)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_ENTRY
ENDBR
swapgs
@@ -112,6 +112,11 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL)
movq %rsp, %rdi
/* Sign extend the lower 32bit as syscall numbers are treated as int */
movslq %eax, %rsi
+
+ /* clobbers %rax, make sure it is after saving the syscall nr */
+ IBRS_ENTER
+ UNTRAIN_RET
+
call do_syscall_64 /* returns with IRQs disabled */
/*
@@ -191,6 +196,7 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL)
* perf profiles. Nothing jumps here.
*/
syscall_return_via_sysret:
+ IBRS_EXIT
POP_REGS pop_rdi=0
/*
@@ -249,7 +255,6 @@ SYM_FUNC_START(__switch_to_asm)
movq %rbx, PER_CPU_VAR(fixed_percpu_data) + stack_canary_offset
#endif
-#ifdef CONFIG_RETPOLINE
/*
* When switching from a shallower to a deeper call stack
* the RSB may either underflow or use entries populated
@@ -258,7 +263,6 @@ SYM_FUNC_START(__switch_to_asm)
* speculative execution to prevent attack.
*/
FILL_RETURN_BUFFER %r12, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW
-#endif
/* restore callee-saved registers */
popq %r15
@@ -322,13 +326,13 @@ SYM_CODE_END(ret_from_fork)
#endif
.endm
-/* Save all registers in pt_regs */
-SYM_CODE_START_LOCAL(push_and_clear_regs)
+SYM_CODE_START_LOCAL(xen_error_entry)
UNWIND_HINT_FUNC
PUSH_AND_CLEAR_REGS save_ret=1
ENCODE_FRAME_POINTER 8
+ UNTRAIN_RET
RET
-SYM_CODE_END(push_and_clear_regs)
+SYM_CODE_END(xen_error_entry)
/**
* idtentry_body - Macro to emit code calling the C function
@@ -337,9 +341,6 @@ SYM_CODE_END(push_and_clear_regs)
*/
.macro idtentry_body cfunc has_error_code:req
- call push_and_clear_regs
- UNWIND_HINT_REGS
-
/*
* Call error_entry() and switch to the task stack if from userspace.
*
@@ -349,7 +350,7 @@ SYM_CODE_END(push_and_clear_regs)
* switch the CR3. So it can skip invoking error_entry().
*/
ALTERNATIVE "call error_entry; movq %rax, %rsp", \
- "", X86_FEATURE_XENPV
+ "call xen_error_entry", X86_FEATURE_XENPV
ENCODE_FRAME_POINTER
UNWIND_HINT_REGS
@@ -612,6 +613,7 @@ __irqentry_text_end:
SYM_CODE_START_LOCAL(common_interrupt_return)
SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL)
+ IBRS_EXIT
#ifdef CONFIG_DEBUG_ENTRY
/* Assert that pt_regs indicates user mode. */
testb $3, CS(%rsp)
@@ -897,6 +899,9 @@ SYM_CODE_END(xen_failsafe_callback)
* 1 -> no SWAPGS on exit
*
* Y GSBASE value at entry, must be restored in paranoid_exit
+ *
+ * R14 - old CR3
+ * R15 - old SPEC_CTRL
*/
SYM_CODE_START_LOCAL(paranoid_entry)
UNWIND_HINT_FUNC
@@ -940,7 +945,7 @@ SYM_CODE_START_LOCAL(paranoid_entry)
* is needed here.
*/
SAVE_AND_SET_GSBASE scratch_reg=%rax save_reg=%rbx
- RET
+ jmp .Lparanoid_gsbase_done
.Lparanoid_entry_checkgs:
/* EBX = 1 -> kernel GSBASE active, no restore required */
@@ -959,8 +964,16 @@ SYM_CODE_START_LOCAL(paranoid_entry)
xorl %ebx, %ebx
swapgs
.Lparanoid_kernel_gsbase:
-
FENCE_SWAPGS_KERNEL_ENTRY
+.Lparanoid_gsbase_done:
+
+ /*
+ * Once we have CR3 and %GS setup save and set SPEC_CTRL. Just like
+ * CR3 above, keep the old value in a callee saved register.
+ */
+ IBRS_ENTER save_reg=%r15
+ UNTRAIN_RET
+
RET
SYM_CODE_END(paranoid_entry)
@@ -982,9 +995,19 @@ SYM_CODE_END(paranoid_entry)
* 1 -> no SWAPGS on exit
*
* Y User space GSBASE, must be restored unconditionally
+ *
+ * R14 - old CR3
+ * R15 - old SPEC_CTRL
*/
SYM_CODE_START_LOCAL(paranoid_exit)
UNWIND_HINT_REGS
+
+ /*
+ * Must restore IBRS state before both CR3 and %GS since we need access
+ * to the per-CPU x86_spec_ctrl_shadow variable.
+ */
+ IBRS_EXIT save_reg=%r15
+
/*
* The order of operations is important. RESTORE_CR3 requires
* kernel GSBASE.
@@ -1017,6 +1040,10 @@ SYM_CODE_END(paranoid_exit)
*/
SYM_CODE_START_LOCAL(error_entry)
UNWIND_HINT_FUNC
+
+ PUSH_AND_CLEAR_REGS save_ret=1
+ ENCODE_FRAME_POINTER 8
+
testb $3, CS+8(%rsp)
jz .Lerror_kernelspace
@@ -1028,9 +1055,12 @@ SYM_CODE_START_LOCAL(error_entry)
FENCE_SWAPGS_USER_ENTRY
/* We have user CR3. Change to kernel CR3. */
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
+ IBRS_ENTER
+ UNTRAIN_RET
leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */
.Lerror_entry_from_usermode_after_swapgs:
+
/* Put us onto the real thread stack. */
call sync_regs
RET
@@ -1065,6 +1095,7 @@ SYM_CODE_START_LOCAL(error_entry)
.Lerror_entry_done_lfence:
FENCE_SWAPGS_KERNEL_ENTRY
leaq 8(%rsp), %rax /* return pt_regs pointer */
+ ANNOTATE_UNRET_END
RET
.Lbstep_iret:
@@ -1080,6 +1111,8 @@ SYM_CODE_START_LOCAL(error_entry)
swapgs
FENCE_SWAPGS_USER_ENTRY
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
+ IBRS_ENTER
+ UNTRAIN_RET
/*
* Pretend that the exception came from user mode: set up pt_regs
@@ -1185,6 +1218,9 @@ SYM_CODE_START(asm_exc_nmi)
PUSH_AND_CLEAR_REGS rdx=(%rdx)
ENCODE_FRAME_POINTER
+ IBRS_ENTER
+ UNTRAIN_RET
+
/*
* At this point we no longer need to worry about stack damage
* due to nesting -- we're on the normal thread stack and we're
@@ -1409,6 +1445,9 @@ end_repeat_nmi:
movq $-1, %rsi
call exc_nmi
+ /* Always restore stashed SPEC_CTRL value (see paranoid_entry) */
+ IBRS_EXIT save_reg=%r15
+
/* Always restore stashed CR3 value (see paranoid_entry) */
RESTORE_CR3 scratch_reg=%r15 save_reg=%r14