rajames/LithosAnanke
0
0
Fork 0
Code Issues 26 Pull Requests 1 Actions Packages Projects Releases Activity

fix(amd64): the image runs wherever the firmware loads it -- -fpie, every symbol hidden; qemu-stick-high in acceptance

Browse Source 
The SER5 stopped at the loader's "Loading kernel from ESP...": built -fno-pic -fno-pie with
ImageBase 0, the image carried ~9,000 32-bit absolute addresses, and the firmware loaded it above
2 GiB, where the sign-extended ones (R_X86_64_32S) point into unmapped memory -- a page fault in
debug_checkpoint() before [CKPT 001]. Reproduced on QEMU's pc machine at 3 GiB (#PF, CR2 =
FFFFFFFFBD316542, the right address sign-extended); q35 always loads it below 2 GiB, so no QEMU
boot ever showed it.

amd64 now builds -fpie with kernel/include/starkernel/pie_hidden.h force-included (#pragma GCC
visibility push(hidden)), so globals are RIP-relative and none is reached through a GOT -- the
2026-08-06 bug that put -fno-pic there. The link refuses any object carrying a 32-bit absolute or
GOT relocation (4,531 on the old objects, none now). test_runner.c's visibility("default") on
global_test_stats is kept for the -fPIC ISAs only. make -f kernel/Makefile ARCH=amd64
qemu-stick-high boots the PC stick on pc with 3 GiB and is part of acceptance (.claude/CLAUDE.md).
Captain Bob, 2026-10-29; FABRIC-3.md XLIV.

Verified: qemu-stick-high with Zuse's pair, ok> and 7 ok, RIP sampled inside .text at base
0xBD297000 (logs/20261029-070253); acceptance amd64 -070508, aarch64 -070715, riscv64 -071138,
PARITY:V4_POST tests=538 pass=538 fail=0, POST: PASSED, dict_hash=0xfec8c47cfc6f437f on all;
make -C v4 test-32, 39 suites, 0 failures. Not yet booted on the SER5.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
rajames
2026-10-29 07:34:11 -04:00
co-authored by Claude Opus 5.5
parent 0a31e558be
commit d6ea592c08
13 changed files with 789 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/include/starkernel/pie_hidden.h
+27
View File
@@ -0,0 +1,27 @@
/*
* pie_hidden.h -- every symbol in the amd64 image is the image's own.
*
* Force-included (-include) ahead of every amd64 kernel and loader source by
* kernel/Makefile's ARCH_CFLAGS, together with -fpie. The image is one PE file,
* linked by ld -m i386pep, loaded by the firmware wherever it chooses: a PC's
* firmware puts it above 2 GiB (the Beelink SER5 did), where the 32-bit absolute
* addresses of -fno-pic code are sign-extended into unmapped memory and the
* loader page-faults before its first checkpoint (FABRIC-3.md XLIV). -fpie
* addresses every global relative to RIP, which is right at any load address.
*
* -fpie alone is not enough: GCC treats an extern declaration of default
* visibility as possibly defined in another module and reaches it through the
* GOT. This image has no dynamic linker and ld -m i386pep builds no GOT, so
* such a read returns zero -- the 2026-08-06 bug (FABRIC-0.md). -fvisibility=
* hidden covers definitions only; this pragma covers declarations too, so GCC
* never uses the GOT. (EDK2's GCC X64 ProcessorBind.h does the same.)
*
* The Makefile checks the result: the link fails if any object still carries
* a GOT or 32-bit absolute relocation.
*/
#ifndef STARKERNEL_PIE_HIDDEN_H
#define STARKERNEL_PIE_HIDDEN_H
#pragma GCC visibility push(hidden)
#endif /* STARKERNEL_PIE_HIDDEN_H */