From feea5f36a9dd65a0ff279c71744423c419b77ada Mon Sep 17 00:00:00 2001 From: Andreas Arnez Date: Fri, 12 Dec 2014 14:14:21 +0100 Subject: [PATCH 8/9] gdbserver: Support read-only regsets in linux-low.c For GNU/Linux targets using the regsets interface, this change supports regsets that can be read but not written. The S390 "last break" regset is an example. So far it had been defined with regset->set_request == PTRACE_GETREGSET, such that the respective ptrace call does not cause any harm. Now we just skip the whole read/modify/write sequence for regsets that do not define a fill_function. gdb/gdbserver/ChangeLog: * linux-low.c (regsets_store_inferior_registers): Skip regsets without a fill_function. * linux-s390-low.c (s390_fill_last_break): Remove. (s390_regsets): Set fill_function to NULL for NT_S390_LAST_BREAK. (s390_arch_setup): Use regset's size instead of fill_function for loop end condition. --- gdb/gdbserver/ChangeLog | 9 +++++++++ gdb/gdbserver/linux-low.c | 3 ++- gdb/gdbserver/linux-s390-low.c | 14 ++++---------- 3 files changed, 15 insertions(+), 11 deletions(-) Index: gdb-7.6.1/gdb/gdbserver/linux-low.c =================================================================== --- gdb-7.6.1.orig/gdb/gdbserver/linux-low.c +++ gdb-7.6.1/gdb/gdbserver/linux-low.c @@ -4120,7 +4120,8 @@ regsets_store_inferior_registers (struct void *buf, *data; int nt_type, res; - if (regset->size == 0 || disabled_regsets[regset - target_regsets]) + if (regset->size == 0 || disabled_regsets[regset - target_regsets] + || regset->fill_function == NULL) { regset ++; continue; Index: gdb-7.6.1/gdb/gdbserver/linux-s390-low.c =================================================================== --- gdb-7.6.1.orig/gdb/gdbserver/linux-s390-low.c +++ gdb-7.6.1/gdb/gdbserver/linux-s390-low.c @@ -264,12 +264,6 @@ static void s390_fill_gregset (struct re /* Fill and store functions for extended register sets. */ static void -s390_fill_last_break (struct regcache *regcache, void *buf) -{ - /* Last break address is read-only. */ -} - -static void s390_store_last_break (struct regcache *regcache, const void *buf) { supply_register_by_name (regcache, "last_break", @@ -290,9 +284,9 @@ s390_store_system_call (struct regcache struct regset_info target_regsets[] = { { 0, 0, 0, 0, GENERAL_REGS, s390_fill_gregset, NULL }, - /* Last break address is read-only; do not attempt PTRACE_SETREGSET. */ - { PTRACE_GETREGSET, PTRACE_GETREGSET, NT_S390_LAST_BREAK, 0, - EXTENDED_REGS, s390_fill_last_break, s390_store_last_break }, + /* Last break address is read-only; no fill function. */ + { PTRACE_GETREGSET, -1, NT_S390_LAST_BREAK, 0, EXTENDED_REGS, + NULL, s390_store_last_break }, { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_S390_SYSTEM_CALL, 0, EXTENDED_REGS, s390_fill_system_call, s390_store_system_call }, { 0, 0, 0, -1, -1, NULL, NULL } @@ -454,7 +448,7 @@ s390_arch_setup (void) } #endif /* Update target_regsets according to available register sets. */ - for (regset = target_regsets; regset->fill_function != NULL; regset++) + for (regset = target_regsets; regset->size >= 0; regset++) if (regset->get_request == PTRACE_GETREGSET) switch (regset->nt_type) {