From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59590) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X0Yzq-0004Kr-T9 for qemu-devel@nongnu.org; Fri, 27 Jun 2014 12:27:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X0Yzj-0003nc-Mr for qemu-devel@nongnu.org; Fri, 27 Jun 2014 12:27:30 -0400 Message-ID: <53AD9B68.30403@suse.de> Date: Fri, 27 Jun 2014 18:27:20 +0200 From: Alexander Graf MIME-Version: 1.0 References: <1403767388-16003-1-git-send-email-Bharat.Bhushan@freescale.com> <1403767388-16003-2-git-send-email-Bharat.Bhushan@freescale.com> <53ABF435.2060500@suse.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 5/5 v5] ppc: Add hw breakpoint watchpoint support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Bharat.Bhushan@freescale.com" Cc: "maddy@linux.vnet.ibm.com" , "qemu-ppc@nongnu.org" , "qemu-devel@nongnu.org" On 27.06.14 07:51, Bharat.Bhushan@freescale.com wrote: > >> -----Original Message----- >> From: Alexander Graf [mailto:agraf@suse.de] >> Sent: Thursday, June 26, 2014 3:52 PM >> To: Bhushan Bharat-R65777 >> Cc: qemu-ppc@nongnu.org; qemu-devel@nongnu.org; maddy@linux.vnet.ibm.com >> Subject: Re: [PATCH 5/5 v5] ppc: Add hw breakpoint watchpoint support >> >> >> On 26.06.14 09:23, Bharat Bhushan wrote: >>> This patch adds hardware breakpoint and hardware watchpoint support >>> for ppc. If the debug interrupt is not handled then this is injected >>> to guest. >>> >>> Signed-off-by: Bharat Bhushan >>> --- >>> v4->v5 >>> - cleanup in kvmppc_hw_debug_points_init() >>> - replaced assert in kvm_arch_insert_hw_breakpoint() with return. >>> This allows gdb to through warning "You may have requested too many >>> hardware breakpoints/watchpoints.". Now user can remove extra breakpint >>> and continue. >>> >>> target-ppc/kvm.c | 238 +++++++++++++++++++++++++++++++++++++++++++++++++++-- >> -- >>> 1 file changed, 223 insertions(+), 15 deletions(-) >>> >>> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index >>> 3195491..3347c1b 100644 >>> --- a/target-ppc/kvm.c >>> +++ b/target-ppc/kvm.c >>> @@ -38,6 +38,7 @@ >>> #include "hw/ppc/ppc.h" >>> #include "sysemu/watchdog.h" >>> #include "trace.h" >>> +#include "exec/gdbstub.h" >>> >>> //#define DEBUG_KVM >>> >>> @@ -410,6 +411,38 @@ unsigned long kvm_arch_vcpu_id(CPUState *cpu) >>> return ppc_get_vcpu_dt_id(POWERPC_CPU(cpu)); >>> } >>> >>> +/* e500 supports 2 h/w breakpoint and 2 watchpoint. >>> + * book3s supports only 1 watchpoint, so array size >>> + * of 4 is sufficient for now. >>> + */ >>> +#define MAX_HW_BKPTS 4 >>> + >>> +static struct HWBreakpoint { >>> + target_ulong addr; >>> + int type; >>> +} hw_debug_points[MAX_HW_BKPTS]; >>> + >>> +static CPUWatchpoint hw_watchpoint; >>> + >>> +/* Default there is no breakpoint and watchpoint supported */ static >>> +int max_hw_breakpoint; static int max_hw_watchpoint; static int >>> +nb_hw_breakpoint; static int nb_hw_watchpoint; >>> + >>> +static void kvmppc_hw_debug_points_init(CPUPPCState *cenv) { >>> + if (cenv->excp_model == POWERPC_EXCP_BOOKE) { >>> + max_hw_breakpoint = 2; >>> + max_hw_watchpoint = 2; >>> + } >>> + >>> + if ((max_hw_breakpoint + max_hw_watchpoint) > MAX_HW_BKPTS) { >>> + fprintf(stderr, "Error initializing h/w breakpoints\n"); >>> + return; >>> + } >>> +} >>> + >>> int kvm_arch_init_vcpu(CPUState *cs) >>> { >>> PowerPCCPU *cpu = POWERPC_CPU(cs); @@ -437,6 +470,7 @@ int >>> kvm_arch_init_vcpu(CPUState *cs) >>> } >>> >>> kvm_get_one_reg(cs, KVM_REG_PPC_DEBUG_INST, &debug_inst_opcode); >>> + kvmppc_hw_debug_points_init(cenv); >>> >>> return ret; >>> } >>> @@ -1345,24 +1379,212 @@ int kvm_arch_remove_sw_breakpoint(CPUState *cs, >> struct kvm_sw_breakpoint *bp) >>> return 0; >>> } >>> >>> +static int find_hw_breakpoint(target_ulong addr, int type) { >>> + int n; >>> + >>> + assert((nb_hw_breakpoint + nb_hw_watchpoint) >>> + <= ARRAY_SIZE(hw_debug_points)); >>> + >>> + for (n = 0; n < nb_hw_breakpoint + nb_hw_watchpoint; n++) { >>> + if (hw_debug_points[n].addr == addr && hw_debug_points[n].type == >> type) { >>> + return n; >>> + } >>> + } >>> + >>> + return -1; >>> +} >>> + >>> +static int find_hw_watchpoint(target_ulong addr, int *flag) { >>> + int n; >>> + >>> + n = find_hw_breakpoint(addr, GDB_WATCHPOINT_ACCESS); >>> + if (n >= 0) { >>> + *flag = BP_MEM_ACCESS; >>> + return n; >>> + } >>> + >>> + n = find_hw_breakpoint(addr, GDB_WATCHPOINT_WRITE); >>> + if (n >= 0) { >>> + *flag = BP_MEM_WRITE; >>> + return n; >>> + } >>> + >>> + n = find_hw_breakpoint(addr, GDB_WATCHPOINT_READ); >>> + if (n >= 0) { >>> + *flag = BP_MEM_READ; >>> + return n; >>> + } >>> + >>> + return -1; >>> +} >>> + >>> +int kvm_arch_insert_hw_breakpoint(target_ulong addr, >>> + target_ulong len, int type) { >>> + if ((nb_hw_breakpoint + nb_hw_watchpoint) >= ARRAY_SIZE(hw_debug_points)) >>> + return -ENOBUFS; >>> + >>> + hw_debug_points[nb_hw_breakpoint + nb_hw_watchpoint].addr = addr; >>> + hw_debug_points[nb_hw_breakpoint + nb_hw_watchpoint].type = type; >>> + >>> + switch (type) { >>> + case GDB_BREAKPOINT_HW: >>> + if (nb_hw_breakpoint >= max_hw_breakpoint) { >>> + return -ENOBUFS; >>> + } >>> + >>> + if (find_hw_breakpoint(addr, type) >= 0) { >>> + return -EEXIST; >>> + } >>> + >>> + nb_hw_breakpoint++; >>> + break; >>> + >>> + case GDB_WATCHPOINT_WRITE: >>> + case GDB_WATCHPOINT_READ: >>> + case GDB_WATCHPOINT_ACCESS: >>> + if (nb_hw_watchpoint >= max_hw_watchpoint) { >>> + return -ENOBUFS; >>> + } >>> + >>> + if (find_hw_breakpoint(addr, type) >= 0) { >>> + return -EEXIST; >>> + } >>> + >>> + nb_hw_watchpoint++; >>> + break; >>> + >>> + default: >>> + return -ENOSYS; >>> + } >>> + >>> + return 0; >>> +} >>> + >>> +int kvm_arch_remove_hw_breakpoint(target_ulong addr, >>> + target_ulong len, int type) { >>> + int n; >>> + >>> + n = find_hw_breakpoint(addr, type); >>> + if (n < 0) { >>> + return -ENOENT; >>> + } >>> + >>> + switch (type) { >>> + case GDB_BREAKPOINT_HW: >>> + nb_hw_breakpoint--; >>> + break; >>> + >>> + case GDB_WATCHPOINT_WRITE: >>> + case GDB_WATCHPOINT_READ: >>> + case GDB_WATCHPOINT_ACCESS: >>> + nb_hw_watchpoint--; >>> + break; >>> + >>> + default: >>> + return -ENOSYS; >>> + } >>> + hw_debug_points[n] = hw_debug_points[nb_hw_breakpoint + >>> + nb_hw_watchpoint]; >>> + >>> + return 0; >>> +} >>> + >>> +void kvm_arch_remove_all_hw_breakpoints(void) >>> +{ >>> + nb_hw_breakpoint = nb_hw_watchpoint = 0; } >>> + >>> void kvm_arch_update_guest_debug(CPUState *cs, struct kvm_guest_debug *dbg) >>> { >>> + int n; >>> + >>> /* Software Breakpoint updates */ >>> if (kvm_sw_breakpoints_active(cs)) { >>> dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP; >>> } >>> + >>> + assert((nb_hw_breakpoint + nb_hw_watchpoint) >>> + <= ARRAY_SIZE(hw_debug_points)); >>> + assert((nb_hw_breakpoint + nb_hw_watchpoint) <= >>> + ARRAY_SIZE(dbg->arch.bp)); >>> + >>> + if (nb_hw_breakpoint + nb_hw_watchpoint > 0) { >>> + dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP; >>> + memset(dbg->arch.bp, 0, sizeof(dbg->arch.bp)); >>> + for (n = 0; n < nb_hw_breakpoint + nb_hw_watchpoint; n++) { >>> + switch (hw_debug_points[n].type) { >>> + case GDB_BREAKPOINT_HW: >>> + dbg->arch.bp[n].type = KVMPPC_DEBUG_BREAKPOINT; >>> + break; >>> + case GDB_WATCHPOINT_WRITE: >>> + dbg->arch.bp[n].type = KVMPPC_DEBUG_WATCH_WRITE; >>> + break; >>> + case GDB_WATCHPOINT_READ: >>> + dbg->arch.bp[n].type = KVMPPC_DEBUG_WATCH_READ; >>> + break; >>> + case GDB_WATCHPOINT_ACCESS: >>> + dbg->arch.bp[n].type = KVMPPC_DEBUG_WATCH_WRITE | >>> + KVMPPC_DEBUG_WATCH_READ; >>> + break; >>> + default: >>> + cpu_abort(cs, "Unsupported breakpoint type\n"); >>> + } >>> + dbg->arch.bp[n].addr = hw_debug_points[n].addr; >>> + } >>> + } >>> +} >>> + >>> +static void kvm_e500_handle_debug(CPUState *cs, int handle) { >>> + PowerPCCPU *cpu = POWERPC_CPU(cs); >>> + CPUPPCState *env = &cpu->env; >>> + >>> + env->spr[SPR_BOOKE_DBSR] = 0; >> How would KVM ever know that DBSR is now 0? > Yes, guest will not come to know of this "0" value. I was wrong, thinking about that this will be used in inject_debug_exception(), but inject_debug_exception() is not called in this flow. > >> And why do we need this in the first >> place? The guest's DBSR value doesn't get set on debug interrupts unless we call >> inject_debug_exception(). > vcpu->arch.dbsr is set on debug exception in KVM and that is what guest sees, so we should clear DBSR. Ah, ok. So do we actually need inject_debug_exception()? > >> So there's no need to clear it either, no? > So I think I need a one_reg interface to set/clear DBSR. The sregs interface should be good enough for now, no? Alex