On 17.04.2025 05:12, Marek Marczykowski-Górecki wrote:
> On Fri, Mar 21, 2025 at 10:32:58AM +0000, 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 - 000000007EE21E9A, CS - 0000000000000038, RFLAGS - 0000000000210246
>> RAX - 000000007FF0C1B5, RCX - 0000000000000050, RDX - 0000000000000010
>> RBX - 0000000000000000, RSP - 000000007FF0C180, RBP - 000000007FF0C210
>> RSI - FFFF82D040467CE8, RDI - 0000000000000000
>> R8 - 000000007FF0C1C8, R9 - 000000007FF0C1C0, R10 - 0000000000000000
>> R11 - 0000000000001020, R12 - FFFF82D040467CE8, R13 - 000000007FF0C1B8
>> R14 - 000000007EA33328, R15 - 000000007EA332D8
>> DS - 0000000000000030, ES - 0000000000000030, FS - 0000000000000030
>> GS - 0000000000000030, SS - 0000000000000030
>> CR0 - 0000000080010033, CR2 - FFFF82D040467CE8, CR3 - 000000007FC01000
>> CR4 - 0000000000000668, CR8 - 0000000000000000
>> DR0 - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000
>> DR3 - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400
>> GDTR - 000000007F9DB000 0000000000000047, LDTR - 0000000000000000
>> IDTR - 000000007F48E018 0000000000000FFF, TR - 0000000000000000
>> FXSAVE_STATE - 000000007FF0BDE0
>> !!!! Find image based on IP(0x7EE21E9A) (No PDB)
>> (ImageBase=000000007EE20000, EntryPoint=000000007EE23935) !!!!
>>
>> 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)
>>
>> This partially rollback commit 00d5d5ce23e6.
>>
>> Fixes: 9180f5365524 ("x86: add multiboot2 protocol support for EFI
>> platforms")
>> Signed-off-by: Frediano Ziglio <frediano.zig...@cloud.com>
>
> -no-jump-tables is available since clang 3.9.0 (and since GCC 4.1.0), so
> with upgraded base toolchain requirements it's safe to commit this now.
And is therefore not eligible for backporting, despite the Fixes: tag.
> Acked-by: Marek Marczykowski-Górecki <marma...@invisiblethingslab.com>
Committed.
Jan
