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[PATCH 2/3] x86/entry: Make #PF/NMI more amenable to livepatching
- To: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Mon, 22 Jan 2024 18:17:13 +0000
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
- Delivery-date: Mon, 22 Jan 2024 18:17:35 +0000
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It is bad form to have inter-function fallthrough. It only functions right
now because alignment padding bytes are NOPs.
However, it also interferes with livepatching binary diffs, because the
implicit grouping of the two functions isn't expressed in the ELF metadata.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
CC: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
xen/arch/x86/x86_64/entry.S | 3 +++
1 file changed, 3 insertions(+)
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index c3f6b667a72a..fc64ef1fd460 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -723,7 +723,9 @@ END(common_interrupt)
FUNC(entry_PF)
ENDBR64
movl $X86_EXC_PF, 4(%rsp)
+ jmp handle_exception
END(entry_PF)
+
/* No special register assumptions. */
FUNC(handle_exception, 0)
ALTERNATIVE "", clac, X86_FEATURE_XEN_SMAP
@@ -1023,6 +1025,7 @@ FUNC(entry_NMI)
ENDBR64
pushq $0
movl $X86_EXC_NMI, 4(%rsp)
+ jmp handle_ist_exception
END(entry_NMI)
FUNC(handle_ist_exception)
--
2.30.2
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