From fc93dfd9345bb8b29a62b21cb0447dd1a3815f91 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 25 Apr 2019 10:10:12 +0200 Subject: [PATCH] x86/paravirt: Match paravirt patchlet field definition ordering to initialization ordering Here's the objdump -D output of the PATCH_XXL data table: 0000000000000010 : 10: fa cli 11: fb sti 12: 57 push %rdi 13: 9d popfq 14: 9c pushfq 15: 58 pop %rax 16: 0f 20 d0 mov %cr2,%rax 19: 0f 20 d8 mov %cr3,%rax 1c: 0f 22 df mov %rdi,%cr3 1f: 0f 09 wbinvd 21: 0f 01 f8 swapgs 24: 48 0f 07 sysretq 27: 0f 01 f8 swapgs 2a: 48 89 f8 mov %rdi,%rax Note how this doesn't match up to the source code: static const struct patch_xxl patch_data_xxl = { .irq_irq_disable = { 0xfa }, // cli .irq_irq_enable = { 0xfb }, // sti .irq_save_fl = { 0x9c, 0x58 }, // pushf; pop %[re]ax .mmu_read_cr2 = { 0x0f, 0x20, 0xd0 }, // mov %cr2, %[re]ax .mmu_read_cr3 = { 0x0f, 0x20, 0xd8 }, // mov %cr3, %[re]ax .irq_restore_fl = { 0x57, 0x9d }, // push %rdi; popfq .mmu_write_cr3 = { 0x0f, 0x22, 0xdf }, // mov %rdi, %cr3 .cpu_wbinvd = { 0x0f, 0x09 }, // wbinvd .cpu_usergs_sysret64 = { 0x0f, 0x01, 0xf8, 0x48, 0x0f, 0x07 }, // swapgs; sysretq .cpu_swapgs = { 0x0f, 0x01, 0xf8 }, // swapgs .mov64 = { 0x48, 0x89, 0xf8 }, // mov %rdi, %rax .irq_restore_fl = { 0x50, 0x9d }, // push %eax; popf .mmu_write_cr3 = { 0x0f, 0x22, 0xd8 }, // mov %eax, %cr3 .cpu_iret = { 0xcf }, // iret }; Note how they are reordered: in the generated code .irq_restore_fl comes before .irq_save_fl, etc. This is because the field ordering in struct patch_xxl does not match the initialization ordering of patch_data_xxl. Match up the initialization order with the definition order - this makes the disassembly easily reviewable: 0000000000000010 : 10: fa cli 11: fb sti 12: 9c pushfq 13: 58 pop %rax 14: 0f 20 d0 mov %cr2,%rax 17: 0f 20 d8 mov %cr3,%rax 1a: 0f 22 df mov %rdi,%cr3 1d: 57 push %rdi 1e: 9d popfq 1f: 0f 09 wbinvd 21: 0f 01 f8 swapgs 24: 48 0f 07 sysretq 27: 0f 01 f8 swapgs 2a: 48 89 f8 mov %rdi,%rax Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20190425081012.GA115378@gmail.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/paravirt_patch.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/paravirt_patch.c b/arch/x86/kernel/paravirt_patch.c index 60e7a5e236c0..37b1d43d1e17 100644 --- a/arch/x86/kernel/paravirt_patch.c +++ b/arch/x86/kernel/paravirt_patch.c @@ -21,11 +21,11 @@ struct patch_xxl { const unsigned char irq_irq_disable[1]; const unsigned char irq_irq_enable[1]; - const unsigned char irq_restore_fl[2]; const unsigned char irq_save_fl[2]; const unsigned char mmu_read_cr2[3]; const unsigned char mmu_read_cr3[3]; const unsigned char mmu_write_cr3[3]; + const unsigned char irq_restore_fl[2]; # ifdef CONFIG_X86_64 const unsigned char cpu_wbinvd[2]; const unsigned char cpu_usergs_sysret64[6]; @@ -43,16 +43,16 @@ static const struct patch_xxl patch_data_xxl = { .mmu_read_cr2 = { 0x0f, 0x20, 0xd0 }, // mov %cr2, %[re]ax .mmu_read_cr3 = { 0x0f, 0x20, 0xd8 }, // mov %cr3, %[re]ax # ifdef CONFIG_X86_64 - .irq_restore_fl = { 0x57, 0x9d }, // push %rdi; popfq .mmu_write_cr3 = { 0x0f, 0x22, 0xdf }, // mov %rdi, %cr3 + .irq_restore_fl = { 0x57, 0x9d }, // push %rdi; popfq .cpu_wbinvd = { 0x0f, 0x09 }, // wbinvd .cpu_usergs_sysret64 = { 0x0f, 0x01, 0xf8, 0x48, 0x0f, 0x07 }, // swapgs; sysretq .cpu_swapgs = { 0x0f, 0x01, 0xf8 }, // swapgs .mov64 = { 0x48, 0x89, 0xf8 }, // mov %rdi, %rax # else - .irq_restore_fl = { 0x50, 0x9d }, // push %eax; popf .mmu_write_cr3 = { 0x0f, 0x22, 0xd8 }, // mov %eax, %cr3 + .irq_restore_fl = { 0x50, 0x9d }, // push %eax; popf .cpu_iret = { 0xcf }, // iret # endif }; -- 2.45.2