diff options
Diffstat (limited to 'gdb/arm-linux-tdep.c')
| -rw-r--r-- | gdb/arm-linux-tdep.c | 81 |
1 files changed, 72 insertions, 9 deletions
diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c index cefda62..95d422a 100644 --- a/gdb/arm-linux-tdep.c +++ b/gdb/arm-linux-tdep.c @@ -223,9 +223,10 @@ arm_linux_extract_return_value (struct type *type, #define ARM_LINUX_SIGRETURN_INSTR 0xef900077 #define ARM_LINUX_RT_SIGRETURN_INSTR 0xef9000ad -/* For ARM EABI, recognize the pattern that glibc uses... alternatively, - we could arrange to do this by function name, but they are not always - exported. */ +/* For ARM EABI, the syscall number is not in the SWI instruction + (instead it is loaded into r7). We recognize the pattern that + glibc uses... alternatively, we could arrange to do this by + function name, but they are not always exported. */ #define ARM_SET_R7_SIGRETURN 0xe3a07077 #define ARM_SET_R7_RT_SIGRETURN 0xe3a070ad #define ARM_EABI_SYSCALL 0xef000000 @@ -251,14 +252,67 @@ arm_linux_sigtramp_cache (struct frame_info *next_frame, trad_frame_set_id (this_cache, frame_id_build (sp, func)); } +/* There are a couple of different possible stack layouts that + we need to support. + + Before version 2.6.18, the kernel used completely independent + layouts for non-RT and RT signals. For non-RT signals the stack + began directly with a struct sigcontext. For RT signals the stack + began with two redundant pointers (to the siginfo and ucontext), + and then the siginfo and ucontext. + + As of version 2.6.18, the non-RT signal frame layout starts with + a ucontext and the RT signal frame starts with a siginfo and then + a ucontext. Also, the ucontext now has a designated save area + for coprocessor registers. + + For RT signals, it's easy to tell the difference: we look for + pinfo, the pointer to the siginfo. If it has the expected + value, we have an old layout. If it doesn't, we have the new + layout. + + For non-RT signals, it's a bit harder. We need something in one + layout or the other with a recognizable offset and value. We can't + use the return trampoline, because ARM usually uses SA_RESTORER, + in which case the stack return trampoline is not filled in. + We can't use the saved stack pointer, because sigaltstack might + be in use. So for now we guess the new layout... */ + +/* There are three words (trap_no, error_code, oldmask) in + struct sigcontext before r0. */ +#define ARM_SIGCONTEXT_R0 0xc + +/* There are five words (uc_flags, uc_link, and three for uc_stack) + in the ucontext_t before the sigcontext. */ +#define ARM_UCONTEXT_SIGCONTEXT 0x14 + +/* There are three elements in an rt_sigframe before the ucontext: + pinfo, puc, and info. The first two are pointers and the third + is a struct siginfo, with size 128 bytes. We could follow puc + to the ucontext, but it's simpler to skip the whole thing. */ +#define ARM_OLD_RT_SIGFRAME_SIGINFO 0x8 +#define ARM_OLD_RT_SIGFRAME_UCONTEXT 0x88 + +#define ARM_NEW_RT_SIGFRAME_UCONTEXT 0x80 + +#define ARM_NEW_SIGFRAME_MAGIC 0x5ac3c35a + static void arm_linux_sigreturn_init (const struct tramp_frame *self, struct frame_info *next_frame, struct trad_frame_cache *this_cache, CORE_ADDR func) { - arm_linux_sigtramp_cache (next_frame, this_cache, func, - 0x0c /* Offset to registers. */); + CORE_ADDR sp = frame_unwind_register_unsigned (next_frame, ARM_SP_REGNUM); + ULONGEST uc_flags = read_memory_unsigned_integer (sp, 4); + + if (uc_flags == ARM_NEW_SIGFRAME_MAGIC) + arm_linux_sigtramp_cache (next_frame, this_cache, func, + ARM_UCONTEXT_SIGCONTEXT + + ARM_SIGCONTEXT_R0); + else + arm_linux_sigtramp_cache (next_frame, this_cache, func, + ARM_SIGCONTEXT_R0); } static void @@ -267,10 +321,19 @@ arm_linux_rt_sigreturn_init (const struct tramp_frame *self, struct trad_frame_cache *this_cache, CORE_ADDR func) { - arm_linux_sigtramp_cache (next_frame, this_cache, func, - 0x88 /* Offset to ucontext_t. */ - + 0x14 /* Offset to sigcontext. */ - + 0x0c /* Offset to registers. */); + CORE_ADDR sp = frame_unwind_register_unsigned (next_frame, ARM_SP_REGNUM); + ULONGEST pinfo = read_memory_unsigned_integer (sp, 4); + + if (pinfo == sp + ARM_OLD_RT_SIGFRAME_SIGINFO) + arm_linux_sigtramp_cache (next_frame, this_cache, func, + ARM_OLD_RT_SIGFRAME_UCONTEXT + + ARM_UCONTEXT_SIGCONTEXT + + ARM_SIGCONTEXT_R0); + else + arm_linux_sigtramp_cache (next_frame, this_cache, func, + ARM_NEW_RT_SIGFRAME_UCONTEXT + + ARM_UCONTEXT_SIGCONTEXT + + ARM_SIGCONTEXT_R0); } static struct tramp_frame arm_linux_sigreturn_tramp_frame = { |