mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-17 17:46:43 +07:00
6ca6366220
This patch implements dynamic ftrace for PA-RISC. The required mcount call sequences can get pretty long, so instead of patching the whole call sequence out of the functions, we are using -fpatchable-function-entry from gcc. This puts a configurable amount of NOPS before/at the start of the function. Taking do_sys_open() as example, which would look like this when the call is patched out: 1036b248: 08 00 02 40 nop 1036b24c: 08 00 02 40 nop 1036b250: 08 00 02 40 nop 1036b254: 08 00 02 40 nop 1036b258 <do_sys_open>: 1036b258: 08 00 02 40 nop 1036b25c: 08 03 02 41 copy r3,r1 1036b260: 6b c2 3f d9 stw rp,-14(sp) 1036b264: 08 1e 02 43 copy sp,r3 1036b268: 6f c1 01 00 stw,ma r1,80(sp) When ftrace gets enabled for this function the kernel will patch these NOPs to: 1036b248: 10 19 57 20 <address of ftrace> 1036b24c: 6f c1 00 80 stw,ma r1,40(sp) 1036b250: 48 21 3f d1 ldw -18(r1),r1 1036b254: e8 20 c0 02 bv,n r0(r1) 1036b258 <do_sys_open>: 1036b258: e8 3f 1f df b,l,n .-c,r1 1036b25c: 08 03 02 41 copy r3,r1 1036b260: 6b c2 3f d9 stw rp,-14(sp) 1036b264: 08 1e 02 43 copy sp,r3 1036b268: 6f c1 01 00 stw,ma r1,80(sp) So the first NOP in do_sys_open() will be patched to jump backwards into some minimal trampoline code which pushes a stackframe, saves r1 which holds the return address, loads the address of the real ftrace function, and branches to that location. For 64 Bit things are getting a bit more complicated (and longer) because we must make sure that the address of ftrace location is 8 byte aligned, and the offset passed to ldd for fetching the address is 8 byte aligned as well. Note that gcc has a bug which misplaces the function label, and needs a patch to make dynamic ftrace work. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90751 for details. Signed-off-by: Sven Schnelle <svens@stackframe.org> Signed-off-by: Helge Deller <deller@gmx.de>
40 lines
1.3 KiB
Makefile
40 lines
1.3 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
|
|
#
|
|
# Makefile for arch/parisc/kernel
|
|
#
|
|
|
|
extra-y := head.o vmlinux.lds
|
|
|
|
obj-y := cache.o pacache.o setup.o pdt.o traps.o time.o irq.o \
|
|
pa7300lc.o syscall.o entry.o sys_parisc.o firmware.o \
|
|
ptrace.o hardware.o inventory.o drivers.o alternative.o \
|
|
signal.o hpmc.o real2.o parisc_ksyms.o unaligned.o \
|
|
process.o processor.o pdc_cons.o pdc_chassis.o unwind.o \
|
|
patch.o
|
|
|
|
ifdef CONFIG_FUNCTION_TRACER
|
|
# Do not profile debug and lowlevel utilities
|
|
CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
|
|
CFLAGS_REMOVE_cache.o = $(CC_FLAGS_FTRACE)
|
|
CFLAGS_REMOVE_perf.o = $(CC_FLAGS_FTRACE)
|
|
CFLAGS_REMOVE_unwind.o = $(CC_FLAGS_FTRACE)
|
|
CFLAGS_REMOVE_patch.o = $(CC_FLAGS_FTRACE)
|
|
endif
|
|
|
|
obj-$(CONFIG_SMP) += smp.o
|
|
obj-$(CONFIG_PA11) += pci-dma.o
|
|
obj-$(CONFIG_PCI) += pci.o
|
|
obj-$(CONFIG_MODULES) += module.o
|
|
obj-$(CONFIG_64BIT) += sys_parisc32.o signal32.o
|
|
obj-$(CONFIG_STACKTRACE)+= stacktrace.o
|
|
obj-$(CONFIG_AUDIT) += audit.o
|
|
obj64-$(CONFIG_AUDIT) += compat_audit.o
|
|
# only supported for PCX-W/U in 64-bit mode at the moment
|
|
obj-$(CONFIG_64BIT) += perf.o perf_asm.o $(obj64-y)
|
|
obj-$(CONFIG_PARISC_CPU_TOPOLOGY) += topology.o
|
|
obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o
|
|
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
|
|
obj-$(CONFIG_JUMP_LABEL) += jump_label.o
|
|
obj-$(CONFIG_KGDB) += kgdb.o
|
|
obj-$(CONFIG_KPROBES) += kprobes.o
|