# git rev-parse -q --verify 35f7eea41dba2cdfb11be7a37eb21cf010fd3220^{commit} 35f7eea41dba2cdfb11be7a37eb21cf010fd3220 already have revision, skipping fetch # git checkout -q -f -B kisskb 35f7eea41dba2cdfb11be7a37eb21cf010fd3220 # git clean -qxdf # < git log -1 # commit 35f7eea41dba2cdfb11be7a37eb21cf010fd3220 # Author: Michael Ellerman # Date: Fri Aug 23 22:29:01 2019 +1000 # # powerpc/64: Fix stacktrace on BE when function_graph is enabled # # Currently if we oops or warn while function_graph is active the stack # trace looks like: # .trace_graph_return+0xac/0x100 # .ftrace_return_to_handler+0x98/0x140 # .return_to_handler+0x20/0x40 # .return_to_handler+0x0/0x40 # .return_to_handler+0x0/0x40 # .return_to_handler+0x0/0x40 # .return_to_handler+0x0/0x40 # .return_to_handler+0x0/0x40 # .return_to_handler+0x0/0x40 # .cpu_startup_entry+0x34/0x40 # .start_secondary+0x680/0x6f0 # start_secondary_prolog+0x10/0x14 # # Notice the multiple entries that just show .return_to_handler. # # There is logic in show_stack() to detect this case and print the # traced function, but we inadvertently broke it in commit # 7d56c65a6ff9 ("powerpc/ftrace: Remove mod_return_to_handler") (2014), # because that commit accidentally removed the dereference of rth which # gets the text address from the function descriptor. Hence this is only # broken on big endian (or technically ELFv1). # # Fix it by using the proper accessor, which is ppc_function_entry(). # Result is we get a stack trace such as: # # .trace_graph_return+0x134/0x160 # .ftrace_return_to_handler+0x94/0x140 # .return_to_handler+0x20/0x40 # .return_to_handler+0x0/0x40 (.shared_cede_loop+0x48/0x130) # .return_to_handler+0x0/0x40 (.cpuidle_enter_state+0xa0/0x690) # .return_to_handler+0x0/0x40 (.cpuidle_enter+0x44/0x70) # .return_to_handler+0x0/0x40 (.call_cpuidle+0x68/0xc0) # .return_to_handler+0x0/0x40 (.do_idle+0x37c/0x400) # .return_to_handler+0x0/0x40 (.cpu_startup_entry+0x30/0x50) # .rest_init+0x224/0x348 # # Fixes: 7d56c65a6ff9 ("powerpc/ftrace: Remove mod_return_to_handler") # Signed-off-by: Michael Ellerman # Reviewed-by: Naveen N. Rao # Signed-off-by: Michael Ellerman # Link: https://lore.kernel.org/r/20190823122901.32667-1-mpe@ellerman.id.au # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version # < git log --format=%s --max-count=1 35f7eea41dba2cdfb11be7a37eb21cf010fd3220 # < make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-next_40x_acadia_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- 40x/acadia_defconfig # make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-next_40x_acadia_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- /kisskb/src/arch/powerpc/kernel/head_40x.S: Assembler messages: /kisskb/src/arch/powerpc/kernel/head_40x.S:802: Warning: invalid register expression INFO: Uncompressed kernel (size 0x4be0fc) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x500000) Image Name: Linux-5.3.0-rc2-g35f7eea41dba Created: Thu Sep 5 22:47:02 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2431372 Bytes = 2374.39 KiB = 2.32 MiB Load Address: 00500000 Entry Point: 005017dc Completed OK # rm -rf /kisskb/build/powerpc-next_40x_acadia_defconfig_powerpc-gcc5 # Build took: 0:00:38.820969