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b=nwHlpVjAUt4dHIEIKRYYNtICbchdIO4PS4BHoBalmKmLFKuaBGTgx0x57HuhDNT03 QJZP41o3Q0bN1Wla3i3pM/m16YT6ZP3gPIubbAakGqvBDIrbRRYKpMcAcIifJeEH4t ce9W9LgL69U2JPtrQHEPwjtZ+FY13GlL98uHYUW4vm5b+rTsBM+YWfGXNlCQLGOavc ae2wD7gP2t2o+NnORLMcHB1+aeatGIjHuGRLba+fppZAAlBPPeTVgecBh7R9DUYFki iacaQc++NTBBkdWDmFfN8Geel4YHv1vxCzF1d6E9eADcVmoJmaKJlC+zr3NY77bluZ sehFo4vHlyz3Q== Date: Tue, 27 Jan 2026 09:25:01 +0200 From: Mike Rapoport To: Breno Leitao Cc: Alexander Graf , Pasha Tatashin , Pratyush Yadav , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, usamaarif642@gmail.com, rmikey@meta.com, clm@fb.com, riel@surriel.com, SeongJae Park , kernel-team@meta.com Subject: Re: [PATCH v5 1/4] kho: add size parameter to kho_add_subtree() Message-ID: References: <20260126-kho-v5-0-7cd0f69ab204@debian.org> <20260126-kho-v5-1-7cd0f69ab204@debian.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: BE281A0007 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 1mxzw41kzqpser1hzyhure6hqq1s8wxb X-HE-Tag: 1769498710-16573 X-HE-Meta: U2FsdGVkX1+OS0oSnQ0qxjnI356YjADpjLRIGeJ0MVKLm6Cg15WupT7oepjjwg0RfdkZP4t9EdUQQgUZL/9fEp1dfI1Gvyt0Y9ZHWGvIouT42Vn8Yi1E0UQ9jEggndFeIplJitLGWeALjZ4/m6Lv+dG7W8mU/d5wu+lNZKMVhVe1o/3CaaEgdf18F5+tps0zFrd2RKYRsZkprAZeyN3Hu1ByQiU1cmR7jQ3LF/wLQto8G2OIKiuPkcpTxCBmGc0qt9ZCZqJ0i8CrHtIkB8Wy9AxNz0D13xBgx79wUQfC5Q48dmLvuVPj/P7UeLMJBEwUvJvMOGb0i9Q1jsUnqRYhXiMU1KLAh4ZXpXz3DaNy2mUOnQwKfhFmBTDB2fr+I6dul6J5yZZchUarYdkLPFiWfVUI9gBJBNUSoe1xy7W9fRGcYLriVgxGXgmz4ThMFcgdzrz+cSY6MuCpYnqmSogHItUvmF23Ep2GmtmdFrb8YclGtxlUy6hQeIbBTfgwU4pLH9Ql63lnb0kuJPbfZDWzLZRjzPX+ctkSM5d25YNG5NX4kKYHphml+BcAg6JTo376zhnn9mVU8rI7CWECXkAZ9Ipol8koaNmPEljUBmilztB2wD/s6nppSGnkGkHo8Obdg7TpV0tUBKjhzKJ28zVI3P8XCDpQeAAoQ14FrE85LJX8nBPjn1UuGmMX/7eEgHZDTp/cgcRR8Kd2whNtABwGG7tGR6pZvxXuiB0mlCAlOUdLnwi+0HJxcLfudoXiccEoKZJKuRrXAT1Bih9/BArIQEECK60WTsK8EFq7nPtuq27n13mHfxuPQXUBhndRzY7/u2bdKksTd95qYZFANus5Fem2Q0oI2IeSHFgLzeSa1vGPgQ4gXNSg33UhakSqogxj6Sdv8Aa4pgTAPnXDrWkz5ElZt9NPSltEmiIgS4ph1mBtSEDOHUbkyO3QhKSmWk//eFgEmp8XLJAlqVtmzHI ipI8wjrL E4Ec5lC+8D6GMTCtXWiP+PGgcwKKcVbrMZUnFYHg6yzRfaZMluMOYlr7sGt3ZbGpZLxa573kkFi4rl3id5xKuzeDFXIyRm9SY6FWVhisUllX0BDyaSg9fbzLkoF5dSmlDdPlJKYm40Z5kkJFoe0pBaUv9PfRt5ZKMvtSiFzsjSn0G99aF6btuztFu29GAmFhlGeheRbz2E6Z4FTd1xF2Zx53F+9NLASxWx9HgUg1Guy/jahZ0WD1kkcsPKMi9tZ/onCSDe1KqJ61wWlApS9wKVjU5jO/872PgwpBvaP7fYv1rieoTPzC+CBxSSLLLhYzFCLZ8+wEqMoR2vXPtsO3qfRZNPNuxI7meYGzA X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jan 27, 2026 at 09:23:38AM +0200, Mike Rapoport wrote: > On Mon, Jan 26, 2026 at 08:07:23AM -0800, Breno Leitao wrote: > > kho_add_subtree() assumes the fdt argument is always an FDT and calls > > fdt_totalsize() on it in the debugfs code path. This assumption will > > break if a caller passes arbitrary data instead of an FDT. > > > > When CONFIG_KEXEC_HANDOVER_DEBUGFS is enabled, kho_debugfs_fdt_add() > > calls __kho_debugfs_fdt_add(), which executes: > > > > f->wrapper.size = fdt_totalsize(fdt); > > > > Fix this by adding an explicit size parameter to kho_add_subtree() so > > callers specify the blob size. This allows subtrees to contain > > arbitrary data formats, not just FDTs. Update all callers: > > > > - memblock.c: use fdt_totalsize(fdt) > > - luo_core.c: use fdt_totalsize(fdt_out) > > - test_kho.c: use fdt_totalsize() > > - kexec_handover.c (root fdt): use fdt_totalsize(kho_out.fdt) > > > > Also update kho_in_debugfs_init() to compute sizes using fdt_totalsize() > > for the root and sub-FDTs it processes, since these are known to be > > actual FDT blobs. > > > > Suggested-by: Pratyush Yadav > > Signed-off-by: Breno Leitao > > Reviewed-by: Mike Rapoport (Microsoft) > > > --- > > include/linux/kexec_handover.h | 4 ++-- > > kernel/liveupdate/kexec_handover.c | 8 +++++--- > > kernel/liveupdate/kexec_handover_debugfs.c | 15 +++++++++------ > > kernel/liveupdate/kexec_handover_internal.h | 5 +++-- > > kernel/liveupdate/luo_core.c | 3 ++- > > lib/test_kho.c | 3 ++- > > mm/memblock.c | 2 +- > > 7 files changed, 24 insertions(+), 16 deletions(-) > > > > diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h > > index ac4129d1d7416..abb1d324f42d0 100644 > > --- a/include/linux/kexec_handover.h > > +++ b/include/linux/kexec_handover.h > > @@ -32,7 +32,7 @@ void kho_restore_free(void *mem); > > struct folio *kho_restore_folio(phys_addr_t phys); > > struct page *kho_restore_pages(phys_addr_t phys, unsigned long nr_pages); > > void *kho_restore_vmalloc(const struct kho_vmalloc *preservation); > > -int kho_add_subtree(const char *name, void *fdt); > > +int kho_add_subtree(const char *name, void *fdt, size_t size); > > I'd rename 'void *fdt' to 'void *blob' to make it clearer that subtree isn't > necessary an FDT. Scratch that, I didn't look at the second patch :) > And s/fdt/blob/ in debugfs function names. > All this could be a separate cleanup. > > > -- > Sincerely yours, > Mike. -- Sincerely yours, Mike.