Commits on Jul 13, 2023

1. kpatch-build: account for __pfx_-less NOP padding …

   Some kernel configurations generate function NOP padding, but without
   associated __pfx_<function> symbols.  For example:
   
     $ git describe HEAD
     v6.4-rc7-72-gdad9774deaf1
   
     # Initial default config turns on Indirect Branch Tracking and 16-NOP padding bytes
     $ make defconfig
     $ grep -e CONFIG_X86_KERNEL_IBT -e CONFIG_FUNCTION_PADDING_BYTES .config
     CONFIG_X86_KERNEL_IBT=y
     CONFIG_FUNCTION_PADDING_BYTES=16
   
     # Test .o build generates 16 bytes of NOPs but no "__pfx_" symbol
     $ make -j$(nproc) fs/proc/cmdline.o
     $ objdump -Dr -j .text fs/proc/cmdline.o  | grep -e '<.*>:' -e 'Disassembly'
     Disassembly of section .text:
     0000000000000000 <cmdline_proc_show-0x10>:
     0000000000000010 <cmdline_proc_show>:
   
   This is because objtool operation on the object code may be delayed
   under certain configurations.  As such, create-diff-object should be
   prepared to encounter NOP padded functions in object files before any
   __pfx_ symbols are created.
   
   Fixes: 3e54c63 ("create-diff-object: support x86 NOP-padded functions")
   Closes: dynup#1347 ("x86 NOP padded functions without __pfx_ symbol")
   Reported-by: Ryan Sullivan <[email protected]>
   Signed-off-by: Joe Lawrence <[email protected]>

   

   joe-lawrence committed Jul 13, 2023
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