[xen master] xen: fix unspecified behavior in tr invocation

[patchbot@xxxxxxx]

commit 09a338ae72d2f9dd8e9372669a2ebb2f4652a905
Author:     Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
AuthorDate: Mon Jun 30 10:06:54 2025 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Jun 30 10:06:54 2025 +0200

    xen: fix unspecified behavior in tr invocation
    
    The result of the command is undefined according to the specification if
    the "string2" argument in tr is shorter than "string1". GNU tr behaves
    correctly by extending "string2" to repeat the last character.
    
    Fixes: eb61a4fb14d2 ("xen: fix header guard generation for asm-generic 
headers")
    Reported-by: Jan Beulich <jbeulich@xxxxxxxx>
    Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/scripts/Makefile.asm-generic | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/scripts/Makefile.asm-generic b/xen/scripts/Makefile.asm-generic
index f6850758c5..4e628e116a 100644
--- a/xen/scripts/Makefile.asm-generic
+++ b/xen/scripts/Makefile.asm-generic
@@ -34,7 +34,7 @@ unwanted    := $(filter-out $(generic-y) 
$(generated-y),$(old-headers))
 quiet_cmd_wrap = WRAP    $@
       cmd_wrap = \
        arch=$$(echo $@ | sed -n 's:.*arch/\([^/]*\)/.*:\1:p' | tr a-z A-Z); \
-       upper=$$(echo $*.h | tr a-z A-Z | tr '/.-' '__'); \
+       upper=$$(echo $*.h | tr a-z A-Z | tr '/.-' '___'); \
        echo "\#ifndef $${arch}_GENERIC_$${upper}" > $@.new; \
        echo "\#define $${arch}_GENERIC_$${upper}" >> $@.new; \
        echo "\#include <asm-generic/$*.h>" >> $@.new; \
--
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