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commit 38b55be646e885e283134c51faa014507c8102fd
Author: Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Fri Mar 22 12:08:02 2024 +0000
Commit: Andrew Cooper <andrew.cooper3@citrix.com>
CommitDate: Tue Apr 9 17:16:32 2024 +0100

x86/spec_ctrl: Hold SCF in %ebx across SPEC_CTRL_ENTRY_{PV,INTR}

... as we do in the exit paths too. This will allow simplification to the
sub-blocks.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 9607aeb6602b8ed9962404de3f5f90170ffddb66)
---
xen/arch/x86/x86_64/compat/entry.S | 4 ++--
xen/arch/x86/x86_64/entry.S | 10 +++++-----
xen/include/asm-x86/spec_ctrl_asm.h | 10 +++++++---
3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/xen/arch/x86/x86_64/compat/entry.S b/xen/arch/x86/x86_64/compat/entry.S
index 19a20aec63..2728ea7b49 100644
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -22,7 +22,7 @@ ENTRY(entry_int82)

GET_STACK_END(14)

- SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
+ SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %r14=end, %rdx=0, Clob: abcd */
/* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */

sti
@@ -227,7 +227,7 @@ ENTRY(cstar_enter)

GET_STACK_END(14)

- SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
+ SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %r14=end, %rdx=0, Clob: abcd */
/* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */

mov STACK_CPUINFO_FIELD(xen_cr3)(%r14), %rcx
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 45c8644069..8f07eb0877 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -268,7 +268,7 @@ ENTRY(lstar_enter)

GET_STACK_END(14)

- SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
+ SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %r14=end, %rdx=0, Clob: abcd */
/* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */

mov STACK_CPUINFO_FIELD(xen_cr3)(%r14), %rcx
@@ -307,7 +307,7 @@ GLOBAL(sysenter_eflags_saved)

GET_STACK_END(14)

- SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
+ SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %r14=end, %rdx=0, Clob: abcd */
/* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */

/* PUSHF above has saved EFLAGS.IF clear (the caller had it set). */
@@ -360,7 +360,7 @@ ENTRY(int80_direct_trap)

GET_STACK_END(14)

- SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
+ SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %r14=end, %rdx=0, Clob: abcd */
/* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */

mov STACK_CPUINFO_FIELD(xen_cr3)(%r14), %rcx
@@ -646,7 +646,7 @@ ENTRY(common_interrupt)

GET_STACK_END(14)

- SPEC_CTRL_ENTRY_FROM_INTR /* Req: %rsp=regs, %r14=end, %rdx=0, Clob: acd */
+ SPEC_CTRL_ENTRY_FROM_INTR /* Req: %rsp=regs, %r14=end, %rdx=0, Clob: abcd */
/* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */

mov STACK_CPUINFO_FIELD(xen_cr3)(%r14), %rcx
@@ -680,7 +680,7 @@ GLOBAL(handle_exception)

GET_STACK_END(14)

- SPEC_CTRL_ENTRY_FROM_INTR /* Req: %rsp=regs, %r14=end, %rdx=0, Clob: acd */
+ SPEC_CTRL_ENTRY_FROM_INTR /* Req: %rsp=regs, %r14=end, %rdx=0, Clob: abcd */
/* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */

mov STACK_CPUINFO_FIELD(xen_cr3)(%r14), %rcx
diff --git a/xen/include/asm-x86/spec_ctrl_asm.h b/xen/include/asm-x86/spec_ctrl_asm.h
index 150159e782..b583fd3ed4 100644
--- a/xen/include/asm-x86/spec_ctrl_asm.h
+++ b/xen/include/asm-x86/spec_ctrl_asm.h
@@ -263,9 +263,11 @@
*/
.macro SPEC_CTRL_ENTRY_FROM_PV
/*
- * Requires %rsp=regs/cpuinfo, %rdx=0
- * Clobbers %rax, %rcx, %rdx
+ * Requires %rsp=regs/cpuinfo, %r14=stack_end, %rdx=0
+ * Clobbers %rax, %rbx, %rcx, %rdx
*/
+ movzbl STACK_CPUINFO_FIELD(scf)(%r14), %ebx
+
ALTERNATIVE "", __stringify(DO_SPEC_CTRL_COND_IBPB maybexen=0), \
X86_FEATURE_IBPB_ENTRY_PV

@@ -289,8 +291,10 @@
.macro SPEC_CTRL_ENTRY_FROM_INTR
/*
* Requires %rsp=regs, %r14=stack_end, %rdx=0
- * Clobbers %rax, %rcx, %rdx
+ * Clobbers %rax, %rbx, %rcx, %rdx
*/
+ movzbl STACK_CPUINFO_FIELD(scf)(%r14), %ebx
+
testb $3, UREGS_cs(%rsp)
jz .L\@_skip

--
generated by git-patchbot for /home/xen/git/xen.git#staging-4.15