From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Jan Beulich" <JBeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>
Subject: [PATCH 1/3] x86/kexec: Drop compatibility_mode_far
Date: Fri, 17 Feb 2023 17:48:12 +0000 [thread overview]
Message-ID: <20230217174814.1006961-2-andrew.cooper3@citrix.com> (raw)
In-Reply-To: <20230217174814.1006961-1-andrew.cooper3@citrix.com>
ljmp is (famously?) incompatible between Intel and AMD CPUs, and while we're
using one of the compatible forms, we've got a good stack and lret is the far
more common way of doing this.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>
---
xen/arch/x86/x86_64/kexec_reloc.S | 16 ++++------------
1 file changed, 4 insertions(+), 12 deletions(-)
diff --git a/xen/arch/x86/x86_64/kexec_reloc.S b/xen/arch/x86/x86_64/kexec_reloc.S
index f4842025eb56..035164e96f38 100644
--- a/xen/arch/x86/x86_64/kexec_reloc.S
+++ b/xen/arch/x86/x86_64/kexec_reloc.S
@@ -86,12 +86,11 @@ ENTRY(kexec_reloc)
movq %rax, (compat_mode_gdt_desc + 2)(%rip)
lgdt compat_mode_gdt_desc(%rip)
- /* Relocate compatibility mode entry point address. */
- leal compatibility_mode(%rip), %eax
- movl %eax, compatibility_mode_far(%rip)
-
/* Enter compatibility mode. */
- ljmp *compatibility_mode_far(%rip)
+ lea compatibility_mode(%rip), %rax
+ push $0x10
+ push %rax
+ lretq
relocate_pages:
/* %rdi - indirection page maddr */
@@ -171,13 +170,6 @@ compatibility_mode:
ud2
.align 4
-compatibility_mode_far:
- .long 0x00000000 /* set in call_32_bit above */
- .word 0x0010
-
- .type compatibility_mode_far, @object
- .size compatibility_mode_far, . - compatibility_mode_far
-
compat_mode_gdt_desc:
.word .Lcompat_mode_gdt_end - compat_mode_gdt -1
.quad 0x0000000000000000 /* set in call_32_bit above */
--
2.30.2
next prev parent reply other threads:[~2023-02-17 17:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-17 17:48 [PATCH 0/3] x86/kexec: ASM improvements Andrew Cooper
2023-02-17 17:48 ` Andrew Cooper [this message]
2023-02-21 10:34 ` [PATCH 1/3] x86/kexec: Drop compatibility_mode_far Jan Beulich
2023-02-17 17:48 ` [PATCH 2/3] x86/kexec: Simplify the relocation of compat_mode_gdt_desc Andrew Cooper
2023-02-21 10:48 ` Jan Beulich
2023-02-17 17:48 ` [PATCH 3/3] x86/kexec: Annotate functions with ELF metadata Andrew Cooper
2023-02-21 10:54 ` Jan Beulich
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