# 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/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-gcc --version # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-ld --version # < git log --format=%s --max-count=1 35f7eea41dba2cdfb11be7a37eb21cf010fd3220 # < make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-next_85xx_socrates_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- 85xx/socrates_defconfig # make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-next_85xx_socrates_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:194:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/base/regmap/regmap.c: In function 'regmap_raw_read': /kisskb/src/drivers/base/regmap/regmap.c:2591:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/base/regmap/regmap.c: In function '_regmap_raw_write': /kisskb/src/drivers/base/regmap/regmap.c:1852:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/proc/inode.c: In function 'proc_reg_open': /kisskb/src/include/linux/list.h:65:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/proc/inode.c:338:21: note: 'pdeo' was declared here /kisskb/src/drivers/tty/serial/8250/8250_core.c: In function 'univ8250_release_irq': /kisskb/src/drivers/tty/serial/8250/8250_core.c:248:18: warning: 'i' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/tty/serial/8250/8250_core.c:228:19: note: 'i' was declared here /kisskb/src/drivers/usb/core/devio.c: In function 'async_completed': /kisskb/src/drivers/usb/core/devio.c:613:23: warning: 'errno' may be used uninitialized in this function [-Wuninitialized] INFO: Uncompressed kernel (size 0x59bad0) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x600000) Image Name: Linux-5.3.0-rc2-g35f7eea41dba Created: Thu Sep 5 22:20:42 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2849138 Bytes = 2782.36 KiB = 2.72 MiB Load Address: 00000000 Entry Point: 00000000 Completed OK # rm -rf /kisskb/build/powerpc-next_85xx_socrates_defconfig_powerpc-gcc4.6 # Build took: 0:00:40.608795