Date: Mon, 24 Jul 2023 22:50:11 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 789df254cc9e - main - amd64: Use a larger boot stack Message-ID: <202307242250.36OMoBKk081290@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=789df254cc9e20c860ccc149b94dd1f92843ec9a commit 789df254cc9e20c860ccc149b94dd1f92843ec9a Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2023-07-24 22:47:42 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2023-07-24 22:49:36 +0000 amd64: Use a larger boot stack With sanitizers enabled, it becomes possible to overflow the stack when only a single page is used. Follow arm64's example and use the default kernel stack size instead. This is a bit wasteful, but without a guard page, overflow merely corrupts adjacent .bss entries and is thus difficult to debug. Note, with a GENERIC kernel we already consume over half of the available boot stack space, see the review for an example. Reviewed by: kib Reported by: Jenkins MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D41166 --- sys/amd64/amd64/genassym.c | 1 + sys/amd64/amd64/locore.S | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/sys/amd64/amd64/genassym.c b/sys/amd64/amd64/genassym.c index feb3c7f503ce..4c17561b6e39 100644 --- a/sys/amd64/amd64/genassym.c +++ b/sys/amd64/amd64/genassym.c @@ -116,6 +116,7 @@ ASSYM(KERNBASE, KERNBASE); ASSYM(KERNLOAD, KERNLOAD); ASSYM(DMAP_MIN_ADDRESS, DMAP_MIN_ADDRESS); ASSYM(DMAP_MAX_ADDRESS, DMAP_MAX_ADDRESS); +ASSYM(KSTACK_PAGES, KSTACK_PAGES); ASSYM(PCB_R15, offsetof(struct pcb, pcb_r15)); ASSYM(PCB_R14, offsetof(struct pcb, pcb_r14)); diff --git a/sys/amd64/amd64/locore.S b/sys/amd64/amd64/locore.S index f034a25c9b1b..41386756021e 100644 --- a/sys/amd64/amd64/locore.S +++ b/sys/amd64/amd64/locore.S @@ -48,7 +48,7 @@ .set dmapbase,DMAP_MIN_ADDRESS .set dmapend,DMAP_MAX_ADDRESS -#define BOOTSTACK_SIZE 4096 +#define BOOTSTACK_SIZE (PAGE_SIZE * KSTACK_PAGES) .text /********************************************************************** @@ -148,7 +148,7 @@ ENTRY(la57_trampoline_gdt) ENTRY(la57_trampoline_end) .bss - ALIGN_DATA /* just to be sure */ + .p2align PAGE_SHIFT .globl bootstack .space BOOTSTACK_SIZE /* space for bootstack - temporary stack */ bootstack:
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