diff options
Diffstat (limited to 'target/linux/patches/4.4.20/coldfire-sighandler.patch')
| -rw-r--r-- | target/linux/patches/4.4.20/coldfire-sighandler.patch | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/target/linux/patches/4.4.20/coldfire-sighandler.patch b/target/linux/patches/4.4.20/coldfire-sighandler.patch new file mode 100644 index 000000000..c52a4e228 --- /dev/null +++ b/target/linux/patches/4.4.20/coldfire-sighandler.patch @@ -0,0 +1,100 @@ +From a95517992a37488c0bc8b629c47c570e580e407d Mon Sep 17 00:00:00 2001 +From: Greg Ungerer <gerg@uclinux.org> +Date: Mon, 15 Feb 2016 16:36:29 +1000 +Subject: m68k: Use conventional function parameters for do_sigreturn + +Create conventional stack parameters for the calls to do_sigreturn and +do_rt_sigreturn. The current C code for do_sigreturn and do_rt_sigreturn +dig into the stack to create local pointers to the saved switch stack +and the pt_regs structs. + +The motivation for this change is a problem with non-MMU targets that +have broken signal return paths on newer versions of gcc. It appears as +though gcc has determined that the pointers into the saved stack structs, +and the saved structs themselves, are function parameters and updates to +them will be lost on function return, so they are optimized away. This +results in large parts of restore_sigcontext() and mangle_kernel_stack() +functions being removed. Of course this results in non-functional code +causing kernel oops. This problem has been observed with gcc version +5.2 and 5.3, and probably exists in earlier versions as well. + +Using conventional stack parameter pointers passed to these functions has +the advantage of the code here not needing to know the exact details of +how the underlying entry handler layed these structs out on the stack. +So the rather ugly pointer setup casting and arg referencing can be +removed. + +The resulting code after this change is a few bytes larger (due to the +overhead of creating the stack args and their tear down). Not being hot +paths I don't think this is too much of a problem here. + +An alternative solution is to put a barrier() in the do_sigreturn() code, +but this doesn't feel quite as clean as this solution. + +This change has been compile tested on all defconfigs, and run tested on +Atari (through aranym), ColdFire with MMU (M5407EVB) and ColdFire with +no-MMU (QEMU and M5208EVB). + +Signed-off-by: Greg Ungerer <gerg@uclinux.org> +Acked-by: Andreas Schwab <schwab@linux-m68k.org> +Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> +--- + arch/m68k/kernel/entry.S | 6 ++++++ + arch/m68k/kernel/signal.c | 8 ++------ + 2 files changed, 8 insertions(+), 6 deletions(-) + +diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S +index b54ac7a..97cd3ea 100644 +--- a/arch/m68k/kernel/entry.S ++++ b/arch/m68k/kernel/entry.S +@@ -71,13 +71,19 @@ ENTRY(__sys_vfork) + + ENTRY(sys_sigreturn) + SAVE_SWITCH_STACK ++ movel %sp,%sp@- | switch_stack pointer ++ pea %sp@(SWITCH_STACK_SIZE+4) | pt_regs pointer + jbsr do_sigreturn ++ addql #8,%sp + RESTORE_SWITCH_STACK + rts + + ENTRY(sys_rt_sigreturn) + SAVE_SWITCH_STACK ++ movel %sp,%sp@- | switch_stack pointer ++ pea %sp@(SWITCH_STACK_SIZE+4) | pt_regs pointer + jbsr do_rt_sigreturn ++ addql #8,%sp + RESTORE_SWITCH_STACK + rts + +diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c +index af1c4f3..2dcee3a 100644 +--- a/arch/m68k/kernel/signal.c ++++ b/arch/m68k/kernel/signal.c +@@ -737,10 +737,8 @@ badframe: + return 1; + } + +-asmlinkage int do_sigreturn(unsigned long __unused) ++asmlinkage int do_sigreturn(struct pt_regs *regs, struct switch_stack *sw) + { +- struct switch_stack *sw = (struct switch_stack *) &__unused; +- struct pt_regs *regs = (struct pt_regs *) (sw + 1); + unsigned long usp = rdusp(); + struct sigframe __user *frame = (struct sigframe __user *)(usp - 4); + sigset_t set; +@@ -764,10 +762,8 @@ badframe: + return 0; + } + +-asmlinkage int do_rt_sigreturn(unsigned long __unused) ++asmlinkage int do_rt_sigreturn(struct pt_regs *regs, struct switch_stack *sw) + { +- struct switch_stack *sw = (struct switch_stack *) &__unused; +- struct pt_regs *regs = (struct pt_regs *) (sw + 1); + unsigned long usp = rdusp(); + struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(usp - 4); + sigset_t set; +-- +cgit v0.12 + |