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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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afd30525a6
USERGS_SYSRET64 is used to return from a syscall via SYSRET, but a Xen PV guest will nevertheless use the IRET hypercall, as there is no sysret PV hypercall defined. So instead of testing all the prerequisites for doing a sysret and then mangling the stack for Xen PV again for doing an iret just use the iret exit from the beginning. This can easily be done via an ALTERNATIVE like it is done for the sysenter compat case already. It should be noted that this drops the optimization in Xen for not restoring a few registers when returning to user mode, but it seems as if the saved instructions in the kernel more than compensate for this drop (a kernel build in a Xen PV guest was slightly faster with this patch applied). While at it remove the stale sysret32 remnants. Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210120135555.32594-6-jgross@suse.com
64 lines
1.2 KiB
C
64 lines
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef __LINUX_KBUILD_H
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# error "Please do not build this file directly, build asm-offsets.c instead"
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#endif
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#include <asm/ia32.h>
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#if defined(CONFIG_KVM_GUEST) && defined(CONFIG_PARAVIRT_SPINLOCKS)
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#include <asm/kvm_para.h>
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#endif
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int main(void)
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{
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#ifdef CONFIG_PARAVIRT
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#ifdef CONFIG_PARAVIRT_XXL
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#ifdef CONFIG_DEBUG_ENTRY
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OFFSET(PV_IRQ_save_fl, paravirt_patch_template, irq.save_fl);
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#endif
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#endif
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BLANK();
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#endif
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#if defined(CONFIG_KVM_GUEST) && defined(CONFIG_PARAVIRT_SPINLOCKS)
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OFFSET(KVM_STEAL_TIME_preempted, kvm_steal_time, preempted);
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BLANK();
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#endif
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#define ENTRY(entry) OFFSET(pt_regs_ ## entry, pt_regs, entry)
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ENTRY(bx);
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ENTRY(cx);
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ENTRY(dx);
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ENTRY(sp);
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ENTRY(bp);
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ENTRY(si);
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ENTRY(di);
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ENTRY(r8);
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ENTRY(r9);
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ENTRY(r10);
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ENTRY(r11);
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ENTRY(r12);
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ENTRY(r13);
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ENTRY(r14);
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ENTRY(r15);
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ENTRY(flags);
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BLANK();
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#undef ENTRY
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#define ENTRY(entry) OFFSET(saved_context_ ## entry, saved_context, entry)
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ENTRY(cr0);
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ENTRY(cr2);
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ENTRY(cr3);
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ENTRY(cr4);
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ENTRY(gdt_desc);
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BLANK();
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#undef ENTRY
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BLANK();
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#ifdef CONFIG_STACKPROTECTOR
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DEFINE(stack_canary_offset, offsetof(struct fixed_percpu_data, stack_canary));
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BLANK();
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#endif
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return 0;
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}
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