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Tue, 25 Oct 2022 04:44:23 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 16639A4040; Tue, 25 Oct 2022 04:44:23 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 25 Oct 2022 04:44:23 +0000 (GMT) Received: from li-0d7fa1cc-2c9d-11b2-a85c-aed20764436d.ibm.com (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id 3E2E060805; Tue, 25 Oct 2022 15:44:21 +1100 (AEDT) From: Benjamin Gray To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v9 1/7] powerpc: Allow clearing and restoring registers independent of saved breakpoint state Date: Tue, 25 Oct 2022 15:44:03 +1100 Message-Id: <20221025044409.448755-2-bgray@linux.ibm.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221025044409.448755-1-bgray@linux.ibm.com> References: <20221025044409.448755-1-bgray@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: qyMo33HUJf4K0sgWOm6PRWPqpeN9Jvnd X-Proofpoint-ORIG-GUID: jw4H2Z-ygM20we71IIbK46MYHNsLFqSF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-10-24_09,2022-10-21_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 phishscore=0 bulkscore=0 malwarescore=0 clxscore=1015 impostorscore=0 mlxscore=0 spamscore=0 mlxlogscore=368 adultscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2209130000 definitions=main-2210250024 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ajd@linux.ibm.com, jniethe5@gmail.com, Benjamin Gray , npiggin@gmail.com, cmr@bluescreens.de Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Jordan Niethe For the coming temporary mm used for instruction patching, the breakpoint registers need to be cleared to prevent them from accidentally being triggered. As soon as the patching is done, the breakpoints will be restored. The breakpoint state is stored in the per-cpu variable current_brk[]. Add a suspend_breakpoints() function which will clear the breakpoint registers without touching the state in current_brk[]. Add a pair function restore_breakpoints() which will move the state in current_brk[] back to the registers. Signed-off-by: Jordan Niethe Signed-off-by: Benjamin Gray --- v9: * Renamed ____set_breakpoint to set_hw_breakpoint * Renamed pause/unpause to suspend/restore * Removed unrelated whitespace change --- arch/powerpc/include/asm/debug.h | 2 ++ arch/powerpc/kernel/process.c | 38 +++++++++++++++++++++++++++++--- 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/debug.h b/arch/powerpc/include/asm/debug.h index 86a14736c76c..51c744608f37 100644 --- a/arch/powerpc/include/asm/debug.h +++ b/arch/powerpc/include/asm/debug.h @@ -46,6 +46,8 @@ static inline int debugger_fault_handler(struct pt_regs *regs) { return 0; } #endif void __set_breakpoint(int nr, struct arch_hw_breakpoint *brk); +void suspend_breakpoints(void); +void restore_breakpoints(void); bool ppc_breakpoint_available(void); #ifdef CONFIG_PPC_ADV_DEBUG_REGS extern void do_send_trap(struct pt_regs *regs, unsigned long address, diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 67da147fe34d..5d5109ed01a5 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -862,10 +862,8 @@ static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk) return 0; } -void __set_breakpoint(int nr, struct arch_hw_breakpoint *brk) +static void set_hw_breakpoint(int nr, struct arch_hw_breakpoint *brk) { - memcpy(this_cpu_ptr(¤t_brk[nr]), brk, sizeof(*brk)); - if (dawr_enabled()) // Power8 or later set_dawr(nr, brk); @@ -879,6 +877,12 @@ void __set_breakpoint(int nr, struct arch_hw_breakpoint *brk) WARN_ON_ONCE(1); } +void __set_breakpoint(int nr, struct arch_hw_breakpoint *brk) +{ + memcpy(this_cpu_ptr(¤t_brk[nr]), brk, sizeof(*brk)); + set_hw_breakpoint(nr, brk); +} + /* Check if we have DAWR or DABR hardware */ bool ppc_breakpoint_available(void) { @@ -891,6 +895,34 @@ bool ppc_breakpoint_available(void) } EXPORT_SYMBOL_GPL(ppc_breakpoint_available); +/* Disable the breakpoint in hardware without touching current_brk[] */ +void suspend_breakpoints(void) +{ + struct arch_hw_breakpoint brk = {0}; + int i; + + if (!ppc_breakpoint_available()) + return; + + for (i = 0; i < nr_wp_slots(); i++) + set_hw_breakpoint(i, &brk); +} + +/* + * Re-enable breakpoints suspended by suspend_breakpoints() in hardware + * from current_brk[] + */ +void restore_breakpoints(void) +{ + int i; + + if (!ppc_breakpoint_available()) + return; + + for (i = 0; i < nr_wp_slots(); i++) + set_hw_breakpoint(i, this_cpu_ptr(¤t_brk[i])); +} + #ifdef CONFIG_PPC_TRANSACTIONAL_MEM static inline bool tm_enabled(struct task_struct *tsk)