1 files changed, 111 insertions, 0 deletions

diff --git a/recipes-extended/xen/files/0001-x86-make-hypervisor-build-with-gcc11.patch b/recipes-extended/xen/files/0001-x86-make-hypervisor-build-with-gcc11.patch
new file mode 100644
index 00000000..72592c4b
--- /dev/null
+++ b/recipes-extended/xen/files/0001-x86-make-hypervisor-build-with-gcc11.patch
@@ -0,0 +1,111 @@
+From 722f59d38c710a940ab05e542a83020eb5546dea Mon Sep 17 00:00:00 2001
+From: Jan Beulich <jbeulich@suse.com>
+Date: Thu, 27 May 2021 14:40:29 +0200
+Subject: [PATCH] x86: make hypervisor build with gcc11
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Gcc 11 looks to make incorrect assumptions about valid ranges that
+pointers may be used for addressing when they are derived from e.g. a
+plain constant. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100680.
+
+Utilize RELOC_HIDE() to work around the issue, which for x86 manifests
+in at least
+- mpparse.c:efi_check_config(),
+- tboot.c:tboot_probe(),
+- tboot.c:tboot_gen_frametable_integrity(),
+- x86_emulate.c:x86_emulate() (at -O2 only).
+The last case is particularly odd not just because it only triggers at
+higher optimization levels, but also because it only affects one of at
+least three similar constructs. Various "note" diagnostics claim the
+valid index range to be [0, 2⁶³-1].
+
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Tested-by: Jason Andryuk <jandryuk@gmail.com>
+Acked-by: Roger Pau Monné <roger.pau@citrix.com>
+---
+ tools/tests/x86_emulator/x86-emulate.c | 7 +++++++
+ xen/arch/x86/x86_emulate/x86_emulate.c | 2 +-
+ xen/include/asm-x86/fixmap.h           | 2 +-
+ xen/include/xen/compiler.h             | 6 ++++++
+ xen/include/xen/pdx.h                  | 2 +-
+ 5 files changed, 16 insertions(+), 3 deletions(-)
+
+diff --git a/tools/tests/x86_emulator/x86-emulate.c b/tools/tests/x86_emulator/x86-emulate.c
+index 07f892dbbb..ea286d6ad8 100644
+--- a/tools/tests/x86_emulator/x86-emulate.c
++++ b/tools/tests/x86_emulator/x86-emulate.c
+@@ -8,6 +8,13 @@
+ 
+ #define ERR_PTR(val) NULL
+ 
++/* See gcc bug 100680, but here don't bother making this version dependent. */
++#define gcc11_wrap(x) ({                  \
++    unsigned long x_;                     \
++    __asm__ ( "" : "=g" (x_) : "0" (x) ); \
++    (typeof(x))x_;                        \
++})
++
+ #define cpu_has_amd_erratum(nr) 0
+ #define cpu_has_mpx false
+ #define read_bndcfgu() 0
+diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
+index c25d88d0d8..31fdec030c 100644
+--- a/xen/arch/x86/x86_emulate/x86_emulate.c
++++ b/xen/arch/x86/x86_emulate/x86_emulate.c
+@@ -726,7 +726,7 @@ union vex {
+ #define copy_VEX(ptr, vex) ({ \
+     if ( !mode_64bit() ) \
+         (vex).reg |= 8; \
+-    (ptr)[0 - PFX_BYTES] = ext < ext_8f08 ? 0xc4 : 0x8f; \
++    gcc11_wrap(ptr)[0 - PFX_BYTES] = ext < ext_8f08 ? 0xc4 : 0x8f; \
+     (ptr)[1 - PFX_BYTES] = (vex).raw[0]; \
+     (ptr)[2 - PFX_BYTES] = (vex).raw[1]; \
+     container_of((ptr) + 1 - PFX_BYTES, typeof(vex), raw[0]); \
+diff --git a/xen/include/asm-x86/fixmap.h b/xen/include/asm-x86/fixmap.h
+index 0db314baeb..20746afd0a 100644
+--- a/xen/include/asm-x86/fixmap.h
++++ b/xen/include/asm-x86/fixmap.h
+@@ -78,7 +78,7 @@ extern void __set_fixmap(
+ 
+ #define clear_fixmap(idx) __set_fixmap(idx, 0, 0)
+ 
+-#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
++#define __fix_to_virt(x) gcc11_wrap(FIXADDR_TOP - ((x) << PAGE_SHIFT))
+ #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
+ 
+ #define fix_to_virt(x)   ((void *)__fix_to_virt(x))
+diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
+index 17cf00e1ec..696c7eb89e 100644
+--- a/xen/include/xen/compiler.h
++++ b/xen/include/xen/compiler.h
+@@ -140,6 +140,12 @@
+     __asm__ ("" : "=r"(__ptr) : "0"(ptr));      \
+     (typeof(ptr)) (__ptr + (off)); })
+ 
++#if CONFIG_GCC_VERSION >= 110000 /* See gcc bug 100680. */
++# define gcc11_wrap(x) RELOC_HIDE(x, 0)
++#else
++# define gcc11_wrap(x) (x)
++#endif
++
+ #ifdef __GCC_ASM_FLAG_OUTPUTS__
+ # define ASM_FLAG_OUT(yes, no) yes
+ #else
+diff --git a/xen/include/xen/pdx.h b/xen/include/xen/pdx.h
+index 770fadc06c..9fcfb0ce52 100644
+--- a/xen/include/xen/pdx.h
++++ b/xen/include/xen/pdx.h
+@@ -19,7 +19,7 @@ extern u64 pdx_region_mask(u64 base, u64 len);
+ extern void set_pdx_range(unsigned long smfn, unsigned long emfn);
+ 
+ #define page_to_pdx(pg)  ((pg) - frame_table)
+-#define pdx_to_page(pdx) (frame_table + (pdx))
++#define pdx_to_page(pdx) gcc11_wrap(frame_table + (pdx))
+ 
+ bool __mfn_valid(unsigned long mfn);
+ 
+-- 
+2.25.1
+