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Subject[tip:x86/paravirt] x86/paravirt: Match paravirt patchlet field definition ordering to initialization ordering
Commit-ID:  fc93dfd9345bb8b29a62b21cb0447dd1a3815f91
Gitweb: https://git.kernel.org/tip/fc93dfd9345bb8b29a62b21cb0447dd1a3815f91
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Thu, 25 Apr 2019 10:10:12 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 25 Apr 2019 12:00:44 +0200

x86/paravirt: Match paravirt patchlet field definition ordering to initialization ordering

Here's the objdump -D output of the PATCH_XXL data table:

0000000000000010 <patch_data_xxl>:
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 <patch_data_xxl>:
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 <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190425081012.GA115378@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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
};
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