Mailing List Archive

[xen stable-4.15] x86/entry: Introduce EFRAME_* constants
commit e7a37b9b2c86a17869a201955038d33f23f33b57
Author: Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Sat Jan 27 17:52:09 2024 +0000
Commit: Andrew Cooper <andrew.cooper3@citrix.com>
CommitDate: Tue Mar 12 16:37:44 2024 +0000

x86/entry: Introduce EFRAME_* constants

restore_all_guest() does a lot of manipulation of the stack after popping the
GPRs, and uses raw %rsp displacements to do so. Also, almost all entrypaths
use raw %rsp displacements prior to pushing GPRs.

Provide better mnemonics, to aid readability and reduce the chance of errors
when editing.

No functional change. The resulting binary is identical.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 37541208f119a9c552c6c6c3246ea61be0d44035)
---
xen/arch/x86/x86_64/asm-offsets.c | 17 ++++++++++
xen/arch/x86/x86_64/compat/entry.S | 4 +--
xen/arch/x86/x86_64/entry.S | 68 +++++++++++++++++++-------------------
3 files changed, 53 insertions(+), 36 deletions(-)

diff --git a/xen/arch/x86/x86_64/asm-offsets.c b/xen/arch/x86/x86_64/asm-offsets.c
index 6dbf3bf697..9d105161db 100644
--- a/xen/arch/x86/x86_64/asm-offsets.c
+++ b/xen/arch/x86/x86_64/asm-offsets.c
@@ -51,6 +51,23 @@ void __dummy__(void)
OFFSET(UREGS_kernel_sizeof, struct cpu_user_regs, es);
BLANK();

+ /*
+ * EFRAME_* is for the entry/exit logic where %rsp is pointing at
+ * UREGS_error_code and GPRs are still/already guest values.
+ */
+#define OFFSET_EF(sym, mem) \
+ DEFINE(sym, offsetof(struct cpu_user_regs, mem) - \
+ offsetof(struct cpu_user_regs, error_code))
+
+ OFFSET_EF(EFRAME_entry_vector, entry_vector);
+ OFFSET_EF(EFRAME_rip, rip);
+ OFFSET_EF(EFRAME_cs, cs);
+ OFFSET_EF(EFRAME_eflags, eflags);
+ OFFSET_EF(EFRAME_rsp, rsp);
+ BLANK();
+
+#undef OFFSET_EF
+
OFFSET(VCPU_processor, struct vcpu, processor);
OFFSET(VCPU_domain, struct vcpu, domain);
OFFSET(VCPU_vcpu_info, struct vcpu, vcpu_info);
diff --git a/xen/arch/x86/x86_64/compat/entry.S b/xen/arch/x86/x86_64/compat/entry.S
index cde7702b4c..20603ec4af 100644
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -17,7 +17,7 @@ ENTRY(entry_int82)
ENDBR64
ALTERNATIVE "", clac, X86_FEATURE_XEN_SMAP
pushq $0
- movl $HYPERCALL_VECTOR, 4(%rsp)
+ movl $HYPERCALL_VECTOR, EFRAME_entry_vector(%rsp)
SAVE_ALL compat=1 /* DPL1 gate, restricted to 32bit PV guests only. */

SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
@@ -214,7 +214,7 @@ ENTRY(cstar_enter)
pushq $FLAT_USER_CS32
pushq %rcx
pushq $0
- movl $TRAP_syscall, 4(%rsp)
+ movl $TRAP_syscall, EFRAME_entry_vector(%rsp)
SAVE_ALL

SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index a086349841..fe052d2792 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -190,15 +190,15 @@ restore_all_guest:
SPEC_CTRL_EXIT_TO_PV /* Req: a=spec_ctrl %rsp=regs/cpuinfo, Clob: cd */

RESTORE_ALL
- testw $TRAP_syscall,4(%rsp)
+ testw $TRAP_syscall, EFRAME_entry_vector(%rsp)
jz iret_exit_to_guest

- movq 24(%rsp),%r11 # RFLAGS
+ mov EFRAME_eflags(%rsp), %r11
andq $~(X86_EFLAGS_IOPL | X86_EFLAGS_VM), %r11
orq $X86_EFLAGS_IF,%r11

/* Don't use SYSRET path if the return address is not canonical. */
- movq 8(%rsp),%rcx
+ mov EFRAME_rip(%rsp), %rcx
sarq $47,%rcx
incl %ecx
cmpl $1,%ecx
@@ -213,20 +213,20 @@ restore_all_guest:
ALTERNATIVE "", rag_clrssbsy, X86_FEATURE_XEN_SHSTK
#endif

- movq 8(%rsp), %rcx # RIP
- cmpw $FLAT_USER_CS32,16(%rsp)# CS
- movq 32(%rsp),%rsp # RSP
+ mov EFRAME_rip(%rsp), %rcx
+ cmpw $FLAT_USER_CS32, EFRAME_cs(%rsp)
+ mov EFRAME_rsp(%rsp), %rsp
je 1f
sysretq
1: sysretl

ALIGN
.Lrestore_rcx_iret_exit_to_guest:
- movq 8(%rsp), %rcx # RIP
+ mov EFRAME_rip(%rsp), %rcx
/* No special register assumptions. */
iret_exit_to_guest:
- andl $~(X86_EFLAGS_IOPL | X86_EFLAGS_VM), 24(%rsp)
- orl $X86_EFLAGS_IF,24(%rsp)
+ andl $~(X86_EFLAGS_IOPL | X86_EFLAGS_VM), EFRAME_eflags(%rsp)
+ orl $X86_EFLAGS_IF, EFRAME_eflags(%rsp)
addq $8,%rsp
.Lft0: iretq
_ASM_PRE_EXTABLE(.Lft0, handle_exception)
@@ -257,7 +257,7 @@ ENTRY(lstar_enter)
pushq $FLAT_KERNEL_CS64
pushq %rcx
pushq $0
- movl $TRAP_syscall, 4(%rsp)
+ movl $TRAP_syscall, EFRAME_entry_vector(%rsp)
SAVE_ALL

SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
@@ -295,7 +295,7 @@ GLOBAL(sysenter_eflags_saved)
pushq $3 /* ring 3 null cs */
pushq $0 /* null rip */
pushq $0
- movl $TRAP_syscall, 4(%rsp)
+ movl $TRAP_syscall, EFRAME_entry_vector(%rsp)
SAVE_ALL

SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
@@ -347,7 +347,7 @@ ENTRY(int80_direct_trap)
ENDBR64
ALTERNATIVE "", clac, X86_FEATURE_XEN_SMAP
pushq $0
- movl $0x80, 4(%rsp)
+ movl $0x80, EFRAME_entry_vector(%rsp)
SAVE_ALL

SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */
@@ -650,7 +650,7 @@ ENTRY(common_interrupt)

ENTRY(page_fault)
ENDBR64
- movl $TRAP_page_fault,4(%rsp)
+ movl $TRAP_page_fault, EFRAME_entry_vector(%rsp)
/* No special register assumptions. */
GLOBAL(handle_exception)
ALTERNATIVE "", clac, X86_FEATURE_XEN_SMAP
@@ -790,90 +790,90 @@ FATAL_exception_with_ints_disabled:
ENTRY(divide_error)
ENDBR64
pushq $0
- movl $TRAP_divide_error,4(%rsp)
+ movl $TRAP_divide_error, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(coprocessor_error)
ENDBR64
pushq $0
- movl $TRAP_copro_error,4(%rsp)
+ movl $TRAP_copro_error, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(simd_coprocessor_error)
ENDBR64
pushq $0
- movl $TRAP_simd_error,4(%rsp)
+ movl $TRAP_simd_error, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(device_not_available)
ENDBR64
pushq $0
- movl $TRAP_no_device,4(%rsp)
+ movl $TRAP_no_device, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(debug)
ENDBR64
pushq $0
- movl $TRAP_debug,4(%rsp)
+ movl $TRAP_debug, EFRAME_entry_vector(%rsp)
jmp handle_ist_exception

ENTRY(int3)
ENDBR64
pushq $0
- movl $TRAP_int3,4(%rsp)
+ movl $TRAP_int3, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(overflow)
ENDBR64
pushq $0
- movl $TRAP_overflow,4(%rsp)
+ movl $TRAP_overflow, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(bounds)
ENDBR64
pushq $0
- movl $TRAP_bounds,4(%rsp)
+ movl $TRAP_bounds, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(invalid_op)
ENDBR64
pushq $0
- movl $TRAP_invalid_op,4(%rsp)
+ movl $TRAP_invalid_op, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(invalid_TSS)
ENDBR64
- movl $TRAP_invalid_tss,4(%rsp)
+ movl $TRAP_invalid_tss, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(segment_not_present)
ENDBR64
- movl $TRAP_no_segment,4(%rsp)
+ movl $TRAP_no_segment, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(stack_segment)
ENDBR64
- movl $TRAP_stack_error,4(%rsp)
+ movl $TRAP_stack_error, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(general_protection)
ENDBR64
- movl $TRAP_gp_fault,4(%rsp)
+ movl $TRAP_gp_fault, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(alignment_check)
ENDBR64
- movl $TRAP_alignment_check,4(%rsp)
+ movl $TRAP_alignment_check, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(entry_CP)
ENDBR64
- movl $X86_EXC_CP, 4(%rsp)
+ movl $X86_EXC_CP, EFRAME_entry_vector(%rsp)
jmp handle_exception

ENTRY(double_fault)
ENDBR64
- movl $TRAP_double_fault,4(%rsp)
+ movl $TRAP_double_fault, EFRAME_entry_vector(%rsp)
/* Set AC to reduce chance of further SMAP faults */
ALTERNATIVE "", stac, X86_FEATURE_XEN_SMAP
SAVE_ALL
@@ -899,7 +899,7 @@ ENTRY(double_fault)
.pushsection .init.text, "ax", @progbits
ENTRY(early_page_fault)
ENDBR64
- movl $TRAP_page_fault,4(%rsp)
+ movl $TRAP_page_fault, EFRAME_entry_vector(%rsp)
SAVE_ALL
movq %rsp,%rdi
call do_early_page_fault
@@ -909,7 +909,7 @@ ENTRY(early_page_fault)
ENTRY(nmi)
ENDBR64
pushq $0
- movl $TRAP_nmi,4(%rsp)
+ movl $TRAP_nmi, EFRAME_entry_vector(%rsp)
handle_ist_exception:
ALTERNATIVE "", clac, X86_FEATURE_XEN_SMAP
SAVE_ALL
@@ -1011,7 +1011,7 @@ handle_ist_exception:
ENTRY(machine_check)
ENDBR64
pushq $0
- movl $TRAP_machine_check,4(%rsp)
+ movl $TRAP_machine_check, EFRAME_entry_vector(%rsp)
jmp handle_ist_exception

/* No op trap handler. Required for kexec crash path. */
@@ -1048,7 +1048,7 @@ autogen_stubs: /* Automatically generated stubs. */
1:
ENDBR64
pushq $0
- movb $vec,4(%rsp)
+ movb $vec, EFRAME_entry_vector(%rsp)
jmp common_interrupt

entrypoint 1b
@@ -1062,7 +1062,7 @@ autogen_stubs: /* Automatically generated stubs. */
test $8,%spl /* 64bit exception frames are 16 byte aligned, but the word */
jz 2f /* size is 8 bytes. Check whether the processor gave us an */
pushq $0 /* error code, and insert an empty one if not. */
-2: movb $vec,4(%rsp)
+2: movb $vec, EFRAME_entry_vector(%rsp)
jmp handle_exception

entrypoint 1b
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.15