diff options
Diffstat (limited to 'arch/x86/entry/entry_64.S')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 56 |
1 files changed, 27 insertions, 29 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index e38a4cf795d9..1ffdbfaad2e2 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -574,6 +574,10 @@ SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL) ud2 1: #endif +#ifdef CONFIG_XEN_PV + ALTERNATIVE "", "jmp xenpv_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV +#endif + POP_REGS pop_rdi=0 /* @@ -734,14 +738,10 @@ SYM_FUNC_START(asm_load_gs_index) 2: ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE swapgs FRAME_END - ret -SYM_FUNC_END(asm_load_gs_index) -EXPORT_SYMBOL(asm_load_gs_index) + RET - _ASM_EXTABLE(.Lgs_change, .Lbad_gs) - .section .fixup, "ax" /* running with kernelgs */ -SYM_CODE_START_LOCAL_NOALIGN(.Lbad_gs) +.Lbad_gs: swapgs /* switch back to user gs */ .macro ZAP_GS /* This can't be a string because the preprocessor needs to see it. */ @@ -752,8 +752,11 @@ SYM_CODE_START_LOCAL_NOALIGN(.Lbad_gs) xorl %eax, %eax movl %eax, %gs jmp 2b -SYM_CODE_END(.Lbad_gs) - .previous + + _ASM_EXTABLE(.Lgs_change, .Lbad_gs) + +SYM_FUNC_END(asm_load_gs_index) +EXPORT_SYMBOL(asm_load_gs_index) #ifdef CONFIG_XEN_PV /* @@ -885,11 +888,12 @@ SYM_CODE_START_LOCAL(paranoid_entry) * is needed here. */ SAVE_AND_SET_GSBASE scratch_reg=%rax save_reg=%rbx - ret + RET .Lparanoid_entry_checkgs: /* EBX = 1 -> kernel GSBASE active, no restore required */ movl $1, %ebx + /* * The kernel-enforced convention is a negative GSBASE indicates * a kernel value. No SWAPGS needed on entry and exit. @@ -897,22 +901,15 @@ SYM_CODE_START_LOCAL(paranoid_entry) movl $MSR_GS_BASE, %ecx rdmsr testl %edx, %edx - jns .Lparanoid_entry_swapgs - ret + js .Lparanoid_kernel_gsbase -.Lparanoid_entry_swapgs: + /* EBX = 0 -> SWAPGS required on exit */ + xorl %ebx, %ebx swapgs +.Lparanoid_kernel_gsbase: - /* - * The above SAVE_AND_SWITCH_TO_KERNEL_CR3 macro doesn't do an - * unconditional CR3 write, even in the PTI case. So do an lfence - * to prevent GS speculation, regardless of whether PTI is enabled. - */ FENCE_SWAPGS_KERNEL_ENTRY - - /* EBX = 0 -> SWAPGS required on exit */ - xorl %ebx, %ebx - ret + RET SYM_CODE_END(paranoid_entry) /* @@ -991,12 +988,7 @@ SYM_CODE_START_LOCAL(error_entry) movq %rax, %rsp /* switch stack */ ENCODE_FRAME_POINTER pushq %r12 - ret - -.Lerror_entry_done_lfence: - FENCE_SWAPGS_KERNEL_ENTRY -.Lerror_entry_done: - ret + RET /* * There are two places in the kernel that can potentially fault with @@ -1020,8 +1012,14 @@ SYM_CODE_START_LOCAL(error_entry) * .Lgs_change's error handler with kernel gsbase. */ SWAPGS - FENCE_SWAPGS_USER_ENTRY - jmp .Lerror_entry_done + + /* + * Issue an LFENCE to prevent GS speculation, regardless of whether it is a + * kernel or user gsbase. + */ +.Lerror_entry_done_lfence: + FENCE_SWAPGS_KERNEL_ENTRY + RET .Lbstep_iret: /* Fix truncated RIP */ |