From 5c16595353e0743af99294db48549c3145e3a5ad Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Wed, 9 Aug 2017 23:42:51 -0400 Subject: ARM: signal handling support for FDPIC_FUNCPTRS functions Signal handlers are not direct function pointers but pointers to function descriptor in that case. Therefore we must retrieve the actual function address and load the GOT value into r9 from the descriptor before branching to the actual handler. If a restorer is provided, we also have to load its address and GOT from its descriptor. That descriptor address and the code to load it is pushed onto the stack to be executed as soon as the signal handler returns. However, to be compatible with NX stacks, the FDPIC bounce code is also copied to the signal page along with the other code stubs. Therefore this code must get at the descriptor address whether it executes from the stack or the signal page. To do so we use the stack pointer which points at the signal stack frame where the descriptor address was stored. Because the rt signal frame is different from the simpler frame, two versions of the bounce code are needed, and two variants (ARM and Thumb) as well. The asm-offsets facility is used to determine the actual offset in the signal frame for each version, meaning that struct sigframe and rt_sigframe had to be moved to a separate file. Signed-off-by: Nicolas Pitre Acked-by: Mickael GUENE Tested-by: Vincent Abriou Tested-by: Andras Szemzo --- arch/arm/include/asm/ucontext.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm/include/asm/ucontext.h') diff --git a/arch/arm/include/asm/ucontext.h b/arch/arm/include/asm/ucontext.h index 921d8274855c..b42c75ae0d19 100644 --- a/arch/arm/include/asm/ucontext.h +++ b/arch/arm/include/asm/ucontext.h @@ -2,6 +2,7 @@ #define _ASMARM_UCONTEXT_H #include +#include /* * struct sigcontext only has room for the basic registers, but struct -- cgit