HelenOS sources

ESR_EC_SVC        124 boot/arch/arm64/include/arch/regutils.h #define ESR_EC_SVC  0x15
ESR_EC_SVC        124 kernel/arch/arm64/include/arch/regutils.h #define ESR_EC_SVC  0x15
ESR_EC_SVC        124 uspace/lib/c/arch/arm64/include/libarch/regutils.h #define ESR_EC_SVC  0x15

HelenOS homepage, sources at GitHub