Hi Juergen, It helps to actually Cc the person who broke it ;-)
On Thu, Jun 23, 2022 at 11:46:07AM +0200, Juergen Gross wrote: > Commit e32683c6f7d2 ("x86/mm: Fix RESERVE_BRK() for older binutils") > put the brk area into the .bss..brk section (placed directly behind > .bss), Hm? It didn't actually do that. For individual translation units, it did rename the section from ".brk_reservation" to ".bss..brk". But then during linking it's still placed in .brk in vmlinux, just like before. > causing it not to be cleared initially. As the brk area is used > to allocate early page tables, these might contain garbage in not > explicitly written entries. > > This is especially a problem for Xen PV guests, as the hypervisor will > validate page tables (check for writable page tables and hypervisor > private bits) before accepting them to be used. There have been reports > of early crashes of PV guests due to illegal page table contents. > > Fix that by letting clear_bss() clear the brk area, too. While it does make sense to clear the brk area, I don't understand how my patch broke this. How was it getting cleared before? -- Josh