On 19.08.2024 16:02, Frediano Ziglio wrote: > On Mon, Aug 19, 2024 at 2:19 PM Jan Beulich <[email protected]> wrote: >> >> On 19.08.2024 14:54, Frediano Ziglio wrote: >>> Although code is compiled with -fpic option data is not position >>> independent. This causes data pointer to become invalid if >>> code is not relocated properly which is what happens for >>> efi_multiboot2 which is called by multiboot entry code. >>> >>> Code tested adding >>> PrintErrMesg(L"Test message", EFI_BUFFER_TOO_SMALL); >>> in efi_multiboot2 before calling efi_arch_edd (this function >>> can potentially call PrintErrMesg). >>> >>> Before the patch (XenServer installation on Qemu, xen replaced >>> with vanilla xen.gz): >>> Booting `XenServer (Serial)'Booting `XenServer (Serial)' >>> Test message: !!!! X64 Exception Type - 0E(#PF - Page-Fault) CPU Apic ID >>> - 00000000 !!!! >>> ExceptionData - 0000000000000000 I:0 R:0 U:0 W:0 P:0 PK:0 SS:0 SGX:0 >>> RIP - 000000007DC29E46, CS - 0000000000000038, RFLAGS - 0000000000210246 >>> RAX - 0000000000000000, RCX - 0000000000000050, RDX - 0000000000000000 >>> RBX - 000000007DAB4558, RSP - 000000007EFA1200, RBP - 0000000000000000 >>> RSI - FFFF82D040467A88, RDI - 0000000000000000 >>> R8 - 000000007EFA1238, R9 - 000000007EFA1230, R10 - 0000000000000000 >>> R11 - 000000007CF42665, R12 - FFFF82D040467A88, R13 - 000000007EFA1228 >>> R14 - 000000007EFA1225, R15 - 000000007DAB45A8 >>> DS - 0000000000000030, ES - 0000000000000030, FS - 0000000000000030 >>> GS - 0000000000000030, SS - 0000000000000030 >>> CR0 - 0000000080010033, CR2 - FFFF82D040467A88, CR3 - 000000007EC01000 >>> CR4 - 0000000000000668, CR8 - 0000000000000000 >>> DR0 - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000 >>> DR3 - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400 >>> GDTR - 000000007E9E2000 0000000000000047, LDTR - 0000000000000000 >>> IDTR - 000000007E4E5018 0000000000000FFF, TR - 0000000000000000 >>> FXSAVE_STATE - 000000007EFA0E60 >>> !!!! Find image based on IP(0x7DC29E46) (No PDB) >>> (ImageBase=000000007DC28000, EntryPoint=000000007DC2B917) !!!! >>> >>> After the patch: >>> Booting `XenServer (Serial)'Booting `XenServer (Serial)' >>> Test message: Buffer too small >>> BdsDxe: loading Boot0000 "UiApp" from >>> Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(462CAA21-7614-4503-836E-8AB6F4662331) >>> BdsDxe: starting Boot0000 "UiApp" from >>> Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(462CAA21-7614-4503-836E-8AB6F4662331) >>> >>> Fixes: 00d5d5ce23e6 ("work around Clang generating .data.rel.ro section for >>> init-only files") > > ^^^^ here ??
Did you not see ... >>> Signed-off-by: Frediano Ziglio <[email protected]> >>> --- >>> xen/common/efi/boot.c | 46 ++++++++++++++++++++++++++++++------------- >>> 1 file changed, 32 insertions(+), 14 deletions(-) >>> --- >>> Changes since v1: >>> - added "Fixes:" tag; >>> - fixed cast style change. >>> >>> Changes since v2: >>> - wrap long line. >> >> And what about the Fixes: tag? ... my respective v2 comment then? There I said: "I don't think this is right. While this is where the array was introduced, it was correct at that time afaict. It went wrong when MB2 support was added about a year later. 9180f5365524 ("x86: add multiboot2 protocol support for EFI platforms") may be reasonable to blame, albeit I'm not sure that was the final one, after which MB2 support was considered complete." Jan
