diff options
| -rw-r--r-- | arch/Config.in | 1 | ||||
| -rw-r--r-- | board/qemu/m68k-mcf5208/patches/linux/m68knommu-fix-signal.patch | 45 | ||||
| -rw-r--r-- | configs/qemu_m68k_mcf5208_defconfig | 2 |
3 files changed, 47 insertions, 1 deletions
diff --git a/arch/Config.in b/arch/Config.in index b980e05b9..8000dcaa5 100644 --- a/arch/Config.in +++ b/arch/Config.in @@ -331,7 +331,6 @@ choice config BR2_BINFMT_FLAT_ONE bool "One memory region" - depends on !BR2_m68k help All segments are linked into one memory region. diff --git a/board/qemu/m68k-mcf5208/patches/linux/m68knommu-fix-signal.patch b/board/qemu/m68k-mcf5208/patches/linux/m68knommu-fix-signal.patch new file mode 100644 index 000000000..b56994b23 --- /dev/null +++ b/board/qemu/m68k-mcf5208/patches/linux/m68knommu-fix-signal.patch @@ -0,0 +1,45 @@ +m68knommu: fix user a5 register being overwritten + +On no-MMU systems the application a5 register can be overwitten with the +address of the process data segment when processing application signals. +For flat format applications compiled with full absolute relocation this +effectively corrupts the a5 register on signal processing - and this very +quickly leads to process crash and often takes out the whole system with +a panic as well. + +This has no effect on flat format applications compiled with the more +common PIC methods (such as -msep-data). These format applications reserve +a5 for the pointer to the data segment anyway - so it doesn't change it. + +A long time ago the a5 register was used in the code packed into the user +stack to enable signal return processing. And so it had to be restored on +end of signal cleanup processing back to the original a5 user value. This +was historically done by saving away a5 in the sigcontext structure. At +some point (a long time back it seems) the a5 restore process was changed +and it was hard coded to put the user data segment address directly into a5. +Which is ok for the common PIC compiled application case, but breaks the +full relocation application code. + +We no longer use this type of signal handling mechanism and so we don't +need to do anything special to save and restore a5 at all now. So remove the +code that hard codes a5 to the address of the user data segment. + +Signed-off-by: Greg Ungerer <gerg@linux-m68k.org> +--- + arch/m68k/kernel/signal.c | 1 - + 1 file changed, 1 deletion(-) + +diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c +index 2dcee3a..9202f82 100644 +--- a/arch/m68k/kernel/signal.c ++++ b/arch/m68k/kernel/signal.c +@@ -213,7 +213,6 @@ static inline int frame_extra_sizes(int f) + + static inline void adjustformat(struct pt_regs *regs) + { +- ((struct switch_stack *)regs - 1)->a5 = current->mm->start_data; + /* + * set format byte to make stack appear modulo 4, which it will + * be when doing the rte +-- +1.9.1 diff --git a/configs/qemu_m68k_mcf5208_defconfig b/configs/qemu_m68k_mcf5208_defconfig index f91146760..659ae3d8e 100644 --- a/configs/qemu_m68k_mcf5208_defconfig +++ b/configs/qemu_m68k_mcf5208_defconfig @@ -9,6 +9,8 @@ BR2_SYSTEM_DHCP="eth0" BR2_TARGET_ROOTFS_INITRAMFS=y # BR2_TARGET_ROOTFS_TAR is not set +BR2_GLOBAL_PATCH_DIR="board/qemu/m68k-mcf5208/patches" + # Linux headers same as kernel, a 4.7 series BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_7=y |