Date: Sun, 22 Jun 2025 03:58:10 GMT From: Ahmad Khalifa <vexeduxr@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 308659acbff3 - main - libkvm/kvm_amd64: account for relocatable kernels Message-ID: <202506220358.55M3wAfg041035@gitrepo.freebsd.org>
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The branch main has been updated by vexeduxr: URL: https://cgit.FreeBSD.org/src/commit/?id=308659acbff34c51e57693e4dbfa43cbbc910fa1 commit 308659acbff34c51e57693e4dbfa43cbbc910fa1 Author: Ahmad Khalifa <vexeduxr@FreeBSD.org> AuthorDate: 2025-05-21 20:41:15 +0000 Commit: Ahmad Khalifa <vexeduxr@FreeBSD.org> CommitDate: 2025-06-22 03:49:32 +0000 libkvm/kvm_amd64: account for relocatable kernels amd64 kernels don't have to be loaded at 2M physical anymore, they can be anywhere in the lower 4G of the physical address space. The kernel now provides its physical address in an ELF section in the dump, so account for it. Reviewed by: markj Approved by: imp (mentor) Pull Request: https://github.com/freebsd/freebsd-src/pull/1706 --- lib/libkvm/kvm_amd64.c | 46 +++++++++++++++++++++++++++++++++++++--------- 1 file changed, 37 insertions(+), 9 deletions(-) diff --git a/lib/libkvm/kvm_amd64.c b/lib/libkvm/kvm_amd64.c index e3640cf12243..acc7ac017a3c 100644 --- a/lib/libkvm/kvm_amd64.c +++ b/lib/libkvm/kvm_amd64.c @@ -109,8 +109,9 @@ _amd64_initvtop(kvm_t *kd) { struct kvm_nlist nl[2]; amd64_physaddr_t pa; - kvaddr_t kernbase; + kvaddr_t kernbase, kernphys; amd64_pml4e_t *PML4; + int found = 0; kd->vmst = (struct vmstate *)_kvm_malloc(kd, sizeof(*kd->vmst)); if (kd->vmst == NULL) { @@ -123,16 +124,43 @@ _amd64_initvtop(kvm_t *kd) if (_kvm_read_core_phdrs(kd, &kd->vmst->phnum, &kd->vmst->phdr) == -1) return (-1); + + for (size_t i = 0; i < kd->vmst->phnum; i++) { + if (kd->vmst->phdr[i].p_type == PT_DUMP_DELTA) { + /* Account for the 2M hole at KERNBASE. */ + kernphys = kd->vmst->phdr[i].p_paddr - + kd->vmst->phdr[i].p_align; + kernbase = kd->vmst->phdr[i].p_vaddr; + + found = 1; + break; + } + } } - nl[0].n_name = "kernbase"; - nl[1].n_name = 0; + if (found == 0) { + nl[0].n_name = "kernbase"; + nl[1].n_name = 0; - if (kvm_nlist2(kd, nl) != 0) { - _kvm_err(kd, kd->program, "bad namelist - no kernbase"); - return (-1); + if (kvm_nlist2(kd, nl) != 0) { + _kvm_err(kd, kd->program, "bad namelist - no kernbase"); + return (-1); + } + + nl[0].n_name = "kernphys"; + nl[1].n_name = 0; + + /* XXX + * Relocatable kernels can still be loaded at 2M. + */ + if (kvm_nlist2(kd, nl) != 1) { + _kvm_err(kd, kd->program, "cannot determine kernphys"); + return (-1); + } + + kernphys = 0; + kernbase = nl[0].n_value; } - kernbase = nl[0].n_value; nl[0].n_name = "KPML4phys"; nl[1].n_name = 0; @@ -141,8 +169,8 @@ _amd64_initvtop(kvm_t *kd) _kvm_err(kd, kd->program, "bad namelist - no KPML4phys"); return (-1); } - if (kvm_read2(kd, (nl[0].n_value - kernbase), &pa, sizeof(pa)) != - sizeof(pa)) { + if (kvm_read2(kd, (nl[0].n_value - kernbase + kernphys), &pa, + sizeof(pa)) != sizeof(pa)) { _kvm_err(kd, kd->program, "cannot read KPML4phys"); return (-1); }
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