Re: [PATCH v2 4/5] arm/efi: Simplify efi_arch_handle_cmdline()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 21/11/2023 8:33 pm, Luca Fancellu wrote:
> + CC henry
>
>> On 21 Nov 2023, at 20:15, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>
>> -Wwrite-strings is unhappy with assigning "xen" to a mutable pointer, but 
>> this
>> logic looks incorrect.  It was inherited from the x86 side, where the logic
>> was redundant and has now been removed.
>>
>> In the ARM case it inserts the image name into "xen,xen-bootargs" and there 
>> is
>> no logic at all to strip this before parsing it as the command line.
>>
>> The absence of any logic to strip an image name suggests that it shouldn't
>> exist there, or having a Xen image named e.g. "hmp-unsafe" in the filesystem
>> is going to lead to some unexpected behaviour on boot.
>>
>> No functional change.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>> ---
>> CC: Jan Beulich <JBeulich@xxxxxxxx>
>> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>> CC: Wei Liu <wl@xxxxxxx>
>> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> CC: Julien Grall <julien@xxxxxxx>
>> CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
>> CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
>> CC: Roberto Bagnara <roberto.bagnara@xxxxxxxxxxx>
>> CC: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
>>
>> v2:
>> * New.
>>
>> I'm afraid that all of this reasoning is based on reading the source code.  I
>> don't have any way to try this out in a real ARM UEFI environment.
> I will test this one tomorrow on an arm board

Thanks.  I have a sneaking suspicion that:

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 9b9018574919..8bca5b9a1523 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -46,6 +46,12 @@
 #include <xsm/xsm.h>
 #include <asm/acpi.h>
 
+static int __init parse_ucode(const char *s)
+{
+    panic("Xen image name interpreted as a cmdline parameter\n");
+}
+custom_param("xen.efi", parse_xen);
+
 struct bootinfo __initdata bootinfo;
 
 /*

will trigger.

~Andrew