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go: fix build on ppc64le-musl

This commit is contained in:
q66 2022-04-03 02:32:24 +02:00
parent 3cf615fdae
commit 47d25a40a4
1 changed files with 81 additions and 0 deletions
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srcpkgs/go/patches/fix-ppc64le-startup-detection.patch Normal file
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@ -0,0 +1,81 @@
From 946167906ed8646c433c257b074a10e01f0a7dab Mon Sep 17 00:00:00 2001
From: "Paul E. Murphy" <murp@ibm.com>
Date: Tue, 22 Mar 2022 11:52:02 -0500
Subject: [PATCH] runtime: make static/dynamic startup detection work with musl
on ppc64le
The glibc loader explicitly sets the first doubleword on the stack (R1)
to $0 to indicate it was dynamically loaded.
An ELFv2 ABI compliant loader will set R3/R4 to argc/argv when starting
the process, and R13 to TLS. musl is not compliant. Instead it passes
argc/argv like the kernel, but R3/R4 are in an undefined state and R13
is valid.
With the knowledge above, the startup code can be modified to
dynamically handle all three cases when linked internally.
Fixes #51787
Change-Id: I5de33862c161900d9161817388bbc13a65fdc69c
Reviewed-on: https://go-review.googlesource.com/c/go/+/394654
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Paul Murphy <murp@ibm.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Trust: Paul Murphy <murp@ibm.com>
Trust: Lynn Boger <laboger@linux.vnet.ibm.com>
---
src/runtime/rt0_linux_ppc64le.s | 32 +++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 11 deletions(-)
diff --git a/src/runtime/rt0_linux_ppc64le.s b/src/runtime/rt0_linux_ppc64le.s
index 4f7c6e6c99f6..66f7e7b22a41 100644
--- a/go/src/runtime/rt0_linux_ppc64le.s
+++ b/go/src/runtime/rt0_linux_ppc64le.s
@@ -147,25 +147,35 @@ TEXT _main<>(SB),NOSPLIT,$-8
// In a statically linked binary, the stack contains argc,
// argv as argc string pointers followed by a NULL, envv as a
// sequence of string pointers followed by a NULL, and auxv.
- // There is no TLS base pointer.
+ // The TLS pointer should be initialized to 0.
//
- // In a dynamically linked binary, r3 contains argc, r4
- // contains argv, r5 contains envp, r6 contains auxv, and r13
+ // In an ELFv2 compliant dynamically linked binary, R3 contains argc,
+ // R4 contains argv, R5 contains envp, R6 contains auxv, and R13
// contains the TLS pointer.
//
- // Figure out which case this is by looking at r4: if it's 0,
- // we're statically linked; otherwise we're dynamically
- // linked.
- CMP R0, R4
- BNE dlink
-
- // Statically linked
+ // When loading via glibc, the first doubleword on the stack points
+ // to NULL a value. (that is *(uintptr)(R1) == 0). This is used to
+ // differentiate static vs dynamicly linked binaries.
+ //
+ // If loading with the musl loader, it doesn't follow the ELFv2 ABI. It
+ // passes argc/argv similar to the linux kernel, R13 (TLS) is
+ // initialized, and R3/R4 are undefined.
+ MOVD (R1), R12
+ CMP R0, R12
+ BEQ tls_and_argcv_in_reg
+
+ // Arguments are passed via the stack (musl loader or a static binary)
MOVD 0(R1), R3 // argc
ADD $8, R1, R4 // argv
+
+ // Did the TLS pointer get set? If so, don't change it (e.g musl).
+ CMP R0, R13
+ BNE tls_and_argcv_in_reg
+
MOVD $runtime·m0+m_tls(SB), R13 // TLS
ADD $0x7000, R13
-dlink:
+tls_and_argcv_in_reg:
BR main(SB)
TEXT main(SB),NOSPLIT,$-8