@@ -129,7 +129,7 @@ static inline notrace unsigned long arch_local_irq_save(void)
#define PARAVIRT_ADJUST_EXCEPTION_FRAME /* */
-#define INTERRUPT_RETURN iretq
+#define INTERRUPT_RETURN jmp native_iret
#define USERGS_SYSRET64 \
swapgs; \
sysretq;
@@ -1041,27 +1041,24 @@ restore_args:
RESTORE_ARGS 1,8,1
irq_return:
+ INTERRUPT_RETURN
+
+ENTRY(native_iret)
/*
* Are we returning to a stack segment from the LDT? Note: in
* 64-bit mode SS:RSP on the exception stack is always valid.
*/
#ifdef CONFIG_X86_ESPFIX64
testb $4,(SS-RIP)(%rsp)
- jnz irq_return_ldt
+ jnz native_irq_return_ldt
#endif
-irq_return_iret:
- INTERRUPT_RETURN
- _ASM_EXTABLE(irq_return_iret, bad_iret)
-
-#ifdef CONFIG_PARAVIRT
-ENTRY(native_iret)
+native_irq_return_iret:
iretq
- _ASM_EXTABLE(native_iret, bad_iret)
-#endif
+ _ASM_EXTABLE(native_irq_return_iret, bad_iret)
#ifdef CONFIG_X86_ESPFIX64
-irq_return_ldt:
+native_irq_return_ldt:
pushq_cfi %rax
pushq_cfi %rdi
SWAPGS
@@ -1083,7 +1080,7 @@ irq_return_ldt:
SWAPGS
movq %rax,%rsp
popq_cfi %rax
- jmp irq_return_iret
+ jmp native_irq_return_iret
#endif
.section .fixup,"ax"
@@ -1167,13 +1164,8 @@ __do_double_fault:
cmpl $__KERNEL_CS,CS(%rdi)
jne do_double_fault
movq RIP(%rdi),%rax
- cmpq $irq_return_iret,%rax
-#ifdef CONFIG_PARAVIRT
- je 1f
- cmpq $native_iret,%rax
-#endif
+ cmpq $native_irq_return_iret,%rax
jne do_double_fault /* This shouldn't happen... */
-1:
movq PER_CPU_VAR(kernel_stack),%rax
subq $(6*8-KERNEL_STACK_OFFSET),%rax /* Reset to original stack */
movq %rax,RSP(%rdi)
@@ -1674,7 +1666,7 @@ error_sti:
*/
error_kernelspace:
incl %ebx
- leaq irq_return_iret(%rip),%rcx
+ leaq native_irq_return_iret(%rip),%rcx
cmpq %rcx,RIP+8(%rsp)
je error_swapgs
movl %ecx,%eax /* zero extend */
@@ -6,7 +6,6 @@ DEF_NATIVE(pv_irq_ops, irq_disable, "cli");
DEF_NATIVE(pv_irq_ops, irq_enable, "sti");
DEF_NATIVE(pv_irq_ops, restore_fl, "pushq %rdi; popfq");
DEF_NATIVE(pv_irq_ops, save_fl, "pushfq; popq %rax");
-DEF_NATIVE(pv_cpu_ops, iret, "iretq");
DEF_NATIVE(pv_mmu_ops, read_cr2, "movq %cr2, %rax");
DEF_NATIVE(pv_mmu_ops, read_cr3, "movq %cr3, %rax");
DEF_NATIVE(pv_mmu_ops, write_cr3, "movq %rdi, %cr3");
@@ -50,7 +49,6 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
PATCH_SITE(pv_irq_ops, save_fl);
PATCH_SITE(pv_irq_ops, irq_enable);
PATCH_SITE(pv_irq_ops, irq_disable);
- PATCH_SITE(pv_cpu_ops, iret);
PATCH_SITE(pv_cpu_ops, irq_enable_sysexit);
PATCH_SITE(pv_cpu_ops, usergs_sysret32);
PATCH_SITE(pv_cpu_ops, usergs_sysret64);
This is a note to let you know that I have just added a patch titled x86_64/entry/xen: Do not invoke espfix64 on Xen to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11.7. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 010b8551c65fb49fcc4af5830638ceb105ca0b08 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski <luto@amacapital.net> Date: Wed, 23 Jul 2014 08:34:11 -0700 Subject: x86_64/entry/xen: Do not invoke espfix64 on Xen commit 7209a75d2009dbf7745e2fd354abf25c3deb3ca3 upstream. This moves the espfix64 logic into native_iret. To make this work, it gets rid of the native patch for INTERRUPT_RETURN: INTERRUPT_RETURN on native kernels is now 'jmp native_iret'. This changes the 16-bit SS behavior on Xen from OOPSing to leaking some bits of the Xen hypervisor's RSP (I think). [ hpa: this is a nonzero cost on native, but probably not enough to measure. Xen needs to fix this in their own code, probably doing something equivalent to espfix64. ] Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/7b8f1d8ef6597cb16ae004a43c56980a7de3cf94.1406129132.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/x86/include/asm/irqflags.h | 2 +- arch/x86/kernel/entry_64.S | 28 ++++++++++------------------ arch/x86/kernel/paravirt_patch_64.c | 2 -- 3 files changed, 11 insertions(+), 21 deletions(-) -- 1.9.1