[edk2-devel] [RFT PATCH v3 2/5] UefiCpuPkg/CpuExceptionHandlerLib: Use single SEC/PEI version

[Ard Biesheuvel]

Currently, we use the non-Xcode5 version of ExceptionHandlerAsm.nasm
only for the SEC and PEI phases, and this version was not compatible
with the XCODE or LLD linkers, which do not permit absolute relocations
in read-only sections.

Given that SEC and PEI code typically executes in place from flash and
does not use page alignment for sections, we can simply emit the code
carrying the absolute symbol references into the .data segment instead.
This works around the linker's objections, and the resulting image will
be mapped executable in its entirety anyway. Since this is only needed
for XCODE, let's make this change conditionally using a preprocessor
macro.

Let's rename the .nasm file to reflect the fact that is used for the
SecPei flavor of this library only, and while at it, remove some
unnecessary absolute references.

Also update the Xcode specific version of this library, and use this
source file instead. This is necesessary, as the Xcode specific version
modifies its own code at runtime, which is not permitted in SEC or PEI.
Note that this also removes CET support from the Xcode5 specific build
of the SEC/PEI version of this library, but this is not needed this
early in any case, and this aligns it with other toolchains, which use
this version of the library, which does not have CET support either.

Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
---
 UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuExceptionHandlerLib.inf                                 |  4 +++-
 UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/{ExceptionHandlerAsm.nasm => SecPeiExceptionHandlerAsm.nasm} | 12 ++++++++----
 UefiCpuPkg/Library/CpuExceptionHandlerLib/Xcode5SecPeiCpuExceptionHandlerLib.inf                           |  4 +++-
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuExceptionHandlerLib.inf b/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuExceptionHandlerLib.inf
index df44371fe018e06d..885bb6638ab58620 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuExceptionHandlerLib.inf
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuExceptionHandlerLib.inf
@@ -28,7 +28,7 @@ [Sources.Ia32]
   Ia32/ArchInterruptDefs.h
 
 [Sources.X64]
-  X64/ExceptionHandlerAsm.nasm
+  X64/SecPeiExceptionHandlerAsm.nasm
   X64/ArchExceptionHandler.c
   X64/ArchInterruptDefs.h
 
@@ -58,3 +58,5 @@ [Pcd]
 [FeaturePcd]
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackGuard                    ## CONSUMES
 
+[BuildOptions]
+  XCODE:*_*_X64_PP_FLAGS = -DNO_ABSOLUTE_RELOCS_IN_TEXT
diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/SecPeiExceptionHandlerAsm.nasm
similarity index 94%
rename from UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm
rename to UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/SecPeiExceptionHandlerAsm.nasm
index aaf8d622e6f3b8f1..ec45c60181906c14 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/SecPeiExceptionHandlerAsm.nasm
@@ -27,7 +27,9 @@ extern ASM_PFX(CommonExceptionHandler)
 SECTION .data
 
 DEFAULT REL
+#ifndef NO_ABSOLUTE_RELOCS_IN_TEXT
 SECTION .text
+#endif
 
 ALIGN   8
 
@@ -51,6 +53,9 @@ HookAfterStubHeaderBegin:
     push    rax
     mov     rax, HookAfterStubHeaderEnd
     jmp     rax
+
+SECTION .text
+
 HookAfterStubHeaderEnd:
     mov     rax, rsp
     and     sp,  0xfff0        ; make sure 16-byte aligned for exception context
@@ -276,8 +281,7 @@ DrFinish:
     ; and make sure RSP is 16-byte aligned
     ;
     sub     rsp, 4 * 8 + 8
-    mov     rax, ASM_PFX(CommonExceptionHandler)
-    call    rax
+    call    ASM_PFX(CommonExceptionHandler)
     add     rsp, 4 * 8 + 8
 
     cli
@@ -384,10 +388,10 @@ DoIret:
 ; comments here for definition of address map
 global ASM_PFX(AsmGetTemplateAddressMap)
 ASM_PFX(AsmGetTemplateAddressMap):
-    mov     rax, AsmIdtVectorBegin
+    lea     rax, [AsmIdtVectorBegin]
     mov     qword [rcx], rax
     mov     qword [rcx + 0x8],  (AsmIdtVectorEnd - AsmIdtVectorBegin) / 32
-    mov     rax, HookAfterStubHeaderBegin
+    lea     rax, [HookAfterStubHeaderBegin]
     mov     qword [rcx + 0x10], rax
     ret
 
diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Xcode5SecPeiCpuExceptionHandlerLib.inf b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Xcode5SecPeiCpuExceptionHandlerLib.inf
index 619b39d7f1de9ae3..17f872bb15eb0ff7 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Xcode5SecPeiCpuExceptionHandlerLib.inf
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Xcode5SecPeiCpuExceptionHandlerLib.inf
@@ -33,7 +33,7 @@ [Sources.Ia32]
   Ia32/ArchInterruptDefs.h
 
 [Sources.X64]
-  X64/Xcode5ExceptionHandlerAsm.nasm
+  X64/SecPeiExceptionHandlerAsm.nasm
   X64/ArchExceptionHandler.c
   X64/ArchInterruptDefs.h
 
@@ -63,3 +63,5 @@ [Pcd]
 [FeaturePcd]
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackGuard                    ## CONSUMES
 
+[BuildOptions]
+  XCODE:*_*_X64_PP_FLAGS = -DNO_ABSOLUTE_RELOCS_IN_TEXT
-- 
2.39.2



-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#102257): https://edk2.groups.io/g/devel/message/102257
Mute This Topic: https://groups.io/mt/97969650/1813853
Group Owner: devel+owner at edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [edk2-devel-archive at redhat.com]
-=-=-=-=-=-=-=-=-=-=-=-