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-rw-r--r--arch/x86/entry/calling.h121
1 files changed, 57 insertions, 64 deletions
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index 3f48f695d5e6..be63330c5511 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -97,80 +97,78 @@ For 32-bit we have the following conventions - kernel is built with
#define SIZEOF_PTREGS 21*8
- .macro ALLOC_PT_GPREGS_ON_STACK
- addq $-(15*8), %rsp
- .endm
-
- .macro SAVE_C_REGS_HELPER offset=0 rax=1 rcx=1 r8910=1 r11=1
- .if \r11
- movq %r11, 6*8+\offset(%rsp)
- .endif
- .if \r8910
- movq %r10, 7*8+\offset(%rsp)
- movq %r9, 8*8+\offset(%rsp)
- movq %r8, 9*8+\offset(%rsp)
- .endif
- .if \rax
- movq %rax, 10*8+\offset(%rsp)
+.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0
+ /*
+ * Push registers and sanitize registers of values that a
+ * speculation attack might otherwise want to exploit. The
+ * lower registers are likely clobbered well before they
+ * could be put to use in a speculative execution gadget.
+ * Interleave XOR with PUSH for better uop scheduling:
+ */
+ .if \save_ret
+ pushq %rsi /* pt_regs->si */
+ movq 8(%rsp), %rsi /* temporarily store the return address in %rsi */
+ movq %rdi, 8(%rsp) /* pt_regs->di (overwriting original return address) */
+ .else
+ pushq %rdi /* pt_regs->di */
+ pushq %rsi /* pt_regs->si */
.endif
- .if \rcx
- movq %rcx, 11*8+\offset(%rsp)
+ pushq \rdx /* pt_regs->dx */
+ pushq %rcx /* pt_regs->cx */
+ pushq \rax /* pt_regs->ax */
+ pushq %r8 /* pt_regs->r8 */
+ xorl %r8d, %r8d /* nospec r8 */
+ pushq %r9 /* pt_regs->r9 */
+ xorl %r9d, %r9d /* nospec r9 */
+ pushq %r10 /* pt_regs->r10 */
+ xorl %r10d, %r10d /* nospec r10 */
+ pushq %r11 /* pt_regs->r11 */
+ xorl %r11d, %r11d /* nospec r11*/
+ pushq %rbx /* pt_regs->rbx */
+ xorl %ebx, %ebx /* nospec rbx*/
+ pushq %rbp /* pt_regs->rbp */
+ xorl %ebp, %ebp /* nospec rbp*/
+ pushq %r12 /* pt_regs->r12 */
+ xorl %r12d, %r12d /* nospec r12*/
+ pushq %r13 /* pt_regs->r13 */
+ xorl %r13d, %r13d /* nospec r13*/
+ pushq %r14 /* pt_regs->r14 */
+ xorl %r14d, %r14d /* nospec r14*/
+ pushq %r15 /* pt_regs->r15 */
+ xorl %r15d, %r15d /* nospec r15*/
+ UNWIND_HINT_REGS
+ .if \save_ret
+ pushq %rsi /* return address on top of stack */
.endif
- movq %rdx, 12*8+\offset(%rsp)
- movq %rsi, 13*8+\offset(%rsp)
- movq %rdi, 14*8+\offset(%rsp)
- UNWIND_HINT_REGS offset=\offset extra=0
- .endm
- .macro SAVE_C_REGS offset=0
- SAVE_C_REGS_HELPER \offset, 1, 1, 1, 1
- .endm
- .macro SAVE_C_REGS_EXCEPT_RAX_RCX offset=0
- SAVE_C_REGS_HELPER \offset, 0, 0, 1, 1
- .endm
- .macro SAVE_C_REGS_EXCEPT_R891011
- SAVE_C_REGS_HELPER 0, 1, 1, 0, 0
- .endm
- .macro SAVE_C_REGS_EXCEPT_RCX_R891011
- SAVE_C_REGS_HELPER 0, 1, 0, 0, 0
- .endm
- .macro SAVE_C_REGS_EXCEPT_RAX_RCX_R11
- SAVE_C_REGS_HELPER 0, 0, 0, 1, 0
- .endm
-
- .macro SAVE_EXTRA_REGS offset=0
- movq %r15, 0*8+\offset(%rsp)
- movq %r14, 1*8+\offset(%rsp)
- movq %r13, 2*8+\offset(%rsp)
- movq %r12, 3*8+\offset(%rsp)
- movq %rbp, 4*8+\offset(%rsp)
- movq %rbx, 5*8+\offset(%rsp)
- UNWIND_HINT_REGS offset=\offset
- .endm
-
- .macro POP_EXTRA_REGS
+.endm
+
+.macro POP_REGS pop_rdi=1 skip_r11rcx=0
popq %r15
popq %r14
popq %r13
popq %r12
popq %rbp
popq %rbx
- .endm
-
- .macro POP_C_REGS
+ .if \skip_r11rcx
+ popq %rsi
+ .else
popq %r11
+ .endif
popq %r10
popq %r9
popq %r8
popq %rax
+ .if \skip_r11rcx
+ popq %rsi
+ .else
popq %rcx
+ .endif
popq %rdx
popq %rsi
+ .if \pop_rdi
popq %rdi
- .endm
-
- .macro icebp
- .byte 0xf1
- .endm
+ .endif
+.endm
/*
* This is a sneaky trick to help the unwinder find pt_regs on the stack. The
@@ -178,17 +176,12 @@ For 32-bit we have the following conventions - kernel is built with
* is just setting the LSB, which makes it an invalid stack address and is also
* a signal to the unwinder that it's a pt_regs pointer in disguise.
*
- * NOTE: This macro must be used *after* SAVE_EXTRA_REGS because it corrupts
+ * NOTE: This macro must be used *after* PUSH_AND_CLEAR_REGS because it corrupts
* the original rbp.
*/
.macro ENCODE_FRAME_POINTER ptregs_offset=0
#ifdef CONFIG_FRAME_POINTER
- .if \ptregs_offset
- leaq \ptregs_offset(%rsp), %rbp
- .else
- mov %rsp, %rbp
- .endif
- orq $0x1, %rbp
+ leaq 1+\ptregs_offset(%rsp), %rbp
#endif
.endm