uml: kernel segfaults should dump proper registers
If there's a segfault inside the kernel, we want a dump of the registers at
the point of the segfault, not the registers at the point of calling panic or
the last userspace registers.
sig_handler_common_skas now uses a static register set in the case of a
SIGSEGV to avoid messing up the process registers if the segfault turns out to
be non-fatal.
The architecture sigcontext-to-pt_regs copying code was repurposed to copy
data out of the SEGV stack frame.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/os-Linux/skas/trap.c b/arch/um/os-Linux/skas/trap.c
index 6a20d08..5110eff 100644
--- a/arch/um/os-Linux/skas/trap.c
+++ b/arch/um/os-Linux/skas/trap.c
@@ -15,6 +15,8 @@
#include "sysdep/ptrace_user.h"
#include "os.h"
+static union uml_pt_regs ksig_regs[UM_NR_CPUS];
+
void sig_handler_common_skas(int sig, void *sc_ptr)
{
struct sigcontext *sc = sc_ptr;
@@ -27,10 +29,19 @@
* the process will die.
* XXX Figure out why this is better than SA_NODEFER
*/
- if(sig == SIGSEGV)
+ if(sig == SIGSEGV) {
change_sig(SIGSEGV, 1);
+ /* For segfaults, we want the data from the
+ * sigcontext. In this case, we don't want to mangle
+ * the process registers, so use a static set of
+ * registers. For other signals, the process
+ * registers are OK.
+ */
+ r = &ksig_regs[cpu()];
+ copy_sc(r, sc_ptr);
+ }
+ else r = TASK_REGS(get_current());
- r = TASK_REGS(get_current());
save_user = r->skas.is_user;
r->skas.is_user = 0;
if ( sig == SIGFPE || sig == SIGSEGV ||