Date: Thu, 18 Dec 2025 18:40:58 +0000 From: John Baldwin <jhb@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Cc: Konrad Witaszczyk <def@FreeBSD.org> Subject: git: d866f1d4f968 - stable/14 - aarch64: Save correct value of x18 on trapframe for nested faults Message-ID: <69444aba.31bd2.4e6e954d@gitrepo.freebsd.org>
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The branch stable/14 has been updated by jhb: URL: https://cgit.FreeBSD.org/src/commit/?id=d866f1d4f968f8ead4765944d82f4af640815678 commit d866f1d4f968f8ead4765944d82f4af640815678 Author: Konrad Witaszczyk <def@FreeBSD.org> AuthorDate: 2025-09-16 11:21:57 +0000 Commit: John Baldwin <jhb@FreeBSD.org> CommitDate: 2025-12-18 18:25:14 +0000 aarch64: Save correct value of x18 on trapframe for nested faults x18 is overwritten with a temporary copy of the kernel stack pointer when it is saved in the trapframe. This does not matter in terms of function since nested exception return does not restore x18 from the trapframe, but it does mean that examining x18 in a debugger in stack frames above a nested fault outputs the wrong register value. To fix, compute the value of the original stack pointer to save in x18 later after the trapframe has been constructed. Reviewed by: jhb, andrew Sponsored by: AFRL, DARPA Differential Revision: https://reviews.freebsd.org/D52472 (cherry picked from commit 99213b3c352cdf568ea7cf5b4dddb1879f16a601) --- sys/arm64/arm64/exception.S | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/sys/arm64/arm64/exception.S b/sys/arm64/arm64/exception.S index 0457efe77ba8..07223fcb069d 100644 --- a/sys/arm64/arm64/exception.S +++ b/sys/arm64/arm64/exception.S @@ -38,7 +38,6 @@ */ .macro save_registers_head el .if \el == 1 - mov x18, sp stp x0, x1, [sp, #-(TF_SIZE - TF_X + 128)]! .else stp x0, x1, [sp, #-(TF_SIZE - TF_X)]! @@ -57,7 +56,9 @@ stp x24, x25, [sp, #(24 * 8)] stp x26, x27, [sp, #(26 * 8)] stp x28, x29, [sp, #(28 * 8)] -.if \el == 0 +.if \el == 1 + add x18, sp, #(TF_SIZE - TF_X + 128) +.else mrs x18, sp_el0 .endif mrs x10, elr_el1help
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