From: Joerg Roedel <jroedel@xxxxxxx> Add unconditional cr3 switches between user and kernel cr3 to all non-NMI entry and exit points. Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> --- arch/x86/entry/entry_32.S | 59 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 58 insertions(+), 1 deletion(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 9693485..b5ef003 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -328,6 +328,25 @@ #endif /* CONFIG_X86_ESPFIX32 */ .endm +/* Unconditionally switch to user cr3 */ +.macro SWITCH_TO_USER_CR3 scratch_reg:req + ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI + + movl %cr3, \scratch_reg + orl $PTI_SWITCH_MASK, \scratch_reg + movl \scratch_reg, %cr3 +.Lend_\@: +.endm + +/* Unconditionally switch to kernel cr3 */ +.macro SWITCH_TO_KERNEL_CR3 scratch_reg:req + ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI + movl %cr3, \scratch_reg + andl $(~PTI_SWITCH_MASK), \scratch_reg + movl \scratch_reg, %cr3 +.Lend_\@: +.endm + /* * Called with pt_regs fully populated and kernel segments loaded, @@ -343,6 +362,8 @@ ALTERNATIVE "", "jmp .Lend_\@", X86_FEATURE_XENPV + SWITCH_TO_KERNEL_CR3 scratch_reg=%eax + /* Are we on the entry stack? Bail out if not! */ movl PER_CPU_VAR(cpu_entry_area), %edi addl $CPU_ENTRY_AREA_entry_stack, %edi @@ -637,6 +658,18 @@ ENTRY(xen_sysenter_target) * 0(%ebp) arg6 */ ENTRY(entry_SYSENTER_32) + /* + * On entry-stack with all userspace-regs live - save and + * restore eflags and %eax to use it as scratch-reg for the cr3 + * switch. + */ + pushfl + pushl %eax + SWITCH_TO_KERNEL_CR3 scratch_reg=%eax + popl %eax + popfl + + /* Stack empty again, switch to task stack */ movl TSS_entry_stack(%esp), %esp .Lsysenter_past_esp: @@ -691,6 +724,10 @@ ENTRY(entry_SYSENTER_32) movl PT_OLDESP(%esp), %ecx /* pt_regs->sp */ 1: mov PT_FS(%esp), %fs PTGS_TO_GS + + /* Segments are restored - switch to user cr3 */ + SWITCH_TO_USER_CR3 scratch_reg=%eax + popl %ebx /* pt_regs->bx */ addl $2*4, %esp /* skip pt_regs->cx and pt_regs->dx */ popl %esi /* pt_regs->si */ @@ -778,7 +815,23 @@ restore_all: .Lrestore_all_notrace: CHECK_AND_APPLY_ESPFIX .Lrestore_nocheck: - RESTORE_REGS 4 # skip orig_eax/error_code + /* + * First restore user segments. This can cause exceptions, so we + * run it with kernel cr3. + */ + RESTORE_SEGMENTS + + /* + * Segments are restored - no more exceptions from here on except on + * iret, but that handled safely. + */ + SWITCH_TO_USER_CR3 scratch_reg=%eax + + /* Restore rest */ + RESTORE_INT_REGS + + /* Unwind stack to the iret frame */ + RESTORE_SKIP_SEGMENTS 4 # skip orig_eax/error_code .Lirq_return: INTERRUPT_RETURN @@ -1139,6 +1192,10 @@ ENTRY(debug) SAVE_ALL ENCODE_FRAME_POINTER + + /* Make sure we are running on kernel cr3 */ + SWITCH_TO_KERNEL_CR3 scratch_reg=%eax + xorl %edx, %edx # error code 0 movl %esp, %eax # pt_regs pointer -- 2.7.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
