On Tue, Feb 11, 2025 at 02:11:39PM -0500, Steven Rostedt wrote: > From: Steven Rostedt <rostedt@xxxxxxxxxxx> > > The mcount_loc section holds the addresses of the functions that get > patched by ftrace when enabling function callbacks. It can contain tens of > thousands of entries. These addresses must be sorted. If they are not > sorted at compile time, they are sorted at boot. Sorting at boot does take > some time and does have a small impact on boot performance. > > x86 and arm32 have the addresses in the mcount_loc section of the ELF > file. But for arm64, the section just contains zeros. The .rela.dyn > Elf_Rela section holds the addresses and they get patched at boot during > the relocation phase. > > In order to sort these addresses, the Elf_Rela needs to be updated instead > of the location in the binary that holds the mcount_loc section. Have the > sorttable code, allocate an array to hold the functions, load the > addresses from the Elf_Rela entries, sort them, then put them back in > order into the Elf_rela entries so that they will be sorted at boot up > without having to sort them during boot up. > > Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx> (unless you want this to go in via the arm64 tree)
