[PATCH 0/1] MR11270: configure: Reduce the fixed load address for the preloader on aarch64.

[Martin Storsjö (＠mstorsjo)]

Before ac1761d1dae8bf114a05e28ed6886deba6c2c860, the preloader
was linked with the flags "-static [..] -Wl,-Ttext=0x7d400000"
on aarch64 - with a fixed load address with a 31 bit address.

After that change, we try to use "-static-pie", and if that isn't
supported, we fall back on "-static -Wl,-Ttext=`<address>`" - like
before. However the fixed address used in this codepath was
expanded to a 47 bit address, on 64 bit architectures.

On aarch64, some kernels (in particular for smaller devices?)
are configured with CONFIG_ARM64_VA_BITS=39 (which causes it
to only use 3 levels of translation tables, instead of 4
levels).

Such kernels can't use virtual addresses over 39 bits, while
the fixed address we use in the fallback path is 47 bits.

In the fallback case, when -static-pie isn't supported, use a
39 bit address instead of a 47 bit one, on aarch64.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=59898

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11270

[PATCH 1/1] configure: Reduce the fixed load address for the preloader on aarch64.

[Martin Storsjö]

From: Martin Storsjö <[e-mail]>

Before ac1761d1dae8bf114a05e28ed6886deba6c2c860, the preloader
was linked with the flags "-static [..] -Wl,-Ttext=0x7d400000"
on aarch64 - with a fixed load address with a 31 bit address.

After that change, we try to use "-static-pie", and if that isn't
supported, we fall back on "-static -Wl,-Ttext=<address>" - like
before. However the fixed address used in this codepath was
expanded to a 47 bit address, on 64 bit architectures.

On aarch64, some kernels (in particular for smaller devices?)
are configured with CONFIG_ARM64_VA_BITS=39 (which causes it
to only use 3 levels of translation tables, instead of 4
levels).

Such kernels can't use virtual addresses over 39 bits, while
the fixed address we use in the fallback path is 47 bits.

In the fallback case, when -static-pie isn't supported, use a
39 bit address instead of a 47 bit one, on aarch64.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=59898
---
 configure.ac | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index a8e3bf77076..1059da94871 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1104,7 +1104,16 @@ case $host_os in
           *)
             WINE_TRY_CFLAGS([-static-pie],
                             [AS_VAR_APPEND([WINEPRELOADER_LDFLAGS],[" -static-pie"])],
-                            [AS_VAR_APPEND([WINEPRELOADER_LDFLAGS],[" -static -Wl,-Ttext=0x7d7d00000000"])])
+            [
+                case $HOST_ARCH in
+                  aarch64)
+                    dnl AArch64 kernels may be limited to 39 bits of address
+                    dnl space; limit the text section load address to that.
+                    AS_VAR_APPEND([WINEPRELOADER_LDFLAGS],[" -static -Wl,-Ttext=0x7d7d000000"]) ;;
+                  *)
+                    AS_VAR_APPEND([WINEPRELOADER_LDFLAGS],[" -static -Wl,-Ttext=0x7d7d00000000"]) ;;
+                esac
+            ])
             ;;
         esac
         ;;
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/11270