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Thu, 1 Oct 2026 10:32:50 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 1 Oct 2026 10:32:50 +0000 (GMT) From: Heiko Carstens To: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Niklas Schnelle , Matthew Rosato , Gerald Schaefer , Vineeth Vijayan , Peter Oberparleiter , Harald Freudenberger , Holger Dengler , Stefan Haberland , Jan Hoeppner , Ilya Leoshkevich , Janosch Frank , Claudio Imbrenda Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: [PATCH 08/32] s390/dis: Improve show_code() output Date: Thu, 1 Oct 2026 12:32:23 +0200 Message-ID: <20261001103247.1989111-9-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261001103247.1989111-1-hca@linux.ibm.com> References: <20261001103247.1989111-1-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDAxMDA0MCBTYWx0ZWRfXwcwSnkcCnXD5 DIEYCTjFAUHGR2Md64TeQhFQyivfrMs6wrCIMISDbRqV02fIZXa8iPjVBCPR7oUMGFVWpOoq+3h SywLy45zERqiwffbTo+dm+6VvOGPlJw= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDAxMDA0MCBTYWx0ZWRfX8oFPPTl9ZmsB YkTIWooI8dNeLB+agm3us8WqOuKZNKdOTEzrs1LmDKVZHx5kAIDUSzW5SEdYe1X1pIGcNH2wSp3 BwoW+J0OQqrw3tZQn1wskU/d0V1swbO89biS98dBaNIdkPRK5GzruTGyaaBGzpiwJubYkQi61P/ yZyh2k9P4/d1QWD4yCAB6gNEY7OhC+xlC3vdpk/WeIrg9cSd7D7RCKNzygTYdh9Z9EFD/WnHXcy iLAFITRmIc7AZc3kN7hgyzXuinI9/X99BzAaDPXUDTd33/buVPzShSTa7lhH3IrGfbYfPwz4CbL Nn9nyq90Ctg+yZT/1XnMUa5xds5zBkFDnKtzZfa+XDSNQZ5hIpLZQwa5Y40G0ZkXsvHygQ8NmXT jWBleTJigA2JRj0pyGTyzqI90cjQnRRKEKig8tuIxmWfGaLpi81bdGkDde9s3zmeEc2GZ6RHG91 87MoRV9BVjtf5YAzXMQ== X-Proofpoint-GUID: uMP0Vgf9Oql_lUMIYDCH8MVvdSVCDRPv X-Authority-Analysis: v=2.4 cv=RKcmjIi+ c=1 sm=1 tr=0 ts=6abe36d6 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=pYrMN8t5q59kfUwq7L8A:9 X-Proofpoint-ORIG-GUID: uMP0Vgf9Oql_lUMIYDCH8MVvdSVCDRPv X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-01_03,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 spamscore=0 bulkscore=0 impostorscore=0 adultscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610010040 Replace the '>' and '*' instruction markers with explicit 'PSW >' and 'PGM >' markers which identify both the PSW address and the faulting instruction. Previously, '>' marked the PSW address, while '*' marked the preceding instruction as a guess for the faulting instruction for suppressing exceptions: Krnl Code: 000003ff8dc7bff8: e310f0080004 lg %r1,8(%r15) *000003ff8dc7bffe: e3a0e0000004 lg %r10,0(%r14) >000003ff8dc7c004: a7280000 lhi %r2,0 000003ff8dc7c008: eb9ff0900024 stmg %r9,%r15,144(%r15) Now 'PGM >' explicitly marks the faulting instruction without guessing and 'PSW >' marks the PSW address: Krnl Code: 000003ff8dc7bff8: e310f0080004 lg %r1,8(%r15) PGM >000003ff8dc7bffe: e3a0e0000004 lg %r10,0(%r14) PSW >000003ff8dc7c004: a7280000 lhi %r2,0 000003ff8dc7c008: eb9ff0900024 stmg %r9,%r15,144(%r15) For nullifying exceptions where both addresses are the same, 'PGM+PSW >' is printed instead: Krnl Code: 000003ff8dc7bff8: e310f0080004 lg %r1,8(%r15) PGM+PSW >000003ff8dc7bffe: e3a0e0000004 lg %r10,0(%r14) 000003ff8dc7c004: a7280000 lhi %r2,0 000003ff8dc7c008: eb9ff0900024 stmg %r9,%r15,144(%r15) show_code() may also be called in other contexts where pt_regs does not originate from a program check (e.g. system calls). Introduce and set PIF_PGM_CHECK to indicate when in program check context, and print the PGM marker only in such a context. Note that corner cases are not taken into account. Like before kprobes is not considered, which means that the disassembly may contain unexpected instructions, or that disassembly and/or instruction length count as well as interruption do not match. Signed-off-by: Heiko Carstens --- arch/s390/include/asm/ptrace.h | 4 ++++ arch/s390/kernel/dis.c | 16 +++++++++++----- arch/s390/kernel/early.c | 1 + arch/s390/kernel/traps.c | 4 +++- 4 files changed, 19 insertions(+), 6 deletions(-) diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h index c844b8aa0fd9..3e56ef8c268b 100644 --- a/arch/s390/include/asm/ptrace.h +++ b/arch/s390/include/asm/ptrace.h @@ -18,12 +18,14 @@ #define PIF_SYSCALL_RET_SET 2 /* return value was set via ptrace */ #define PIF_FTRACE_FULL_REGS 3 /* all register contents valid (ftrace) */ #define PIF_WARN_TRAP_SKIPPED 4 /* __WARN_trap() was skipped */ +#define PIF_PGM_CHECK 5 /* inside a program check */ #define _PIF_SYSCALL BIT(PIF_SYSCALL) #define _PIF_ADDR_PSW_ADJUSTED BIT(PIF_PSW_ADDR_ADJUSTED) #define _PIF_SYSCALL_RET_SET BIT(PIF_SYSCALL_RET_SET) #define _PIF_FTRACE_FULL_REGS BIT(PIF_FTRACE_FULL_REGS) #define _PIF_WARN_TRAP_SKIPPED BIT(PIF_WARN_TRAP_SKIPPED) +#define _PIF_PGM_CHECK BIT(PIF_PGM_CHECK) #define PSW32_MASK_PER _AC(0x40000000, UL) #define PSW32_MASK_DAT _AC(0x04000000, UL) @@ -242,6 +244,8 @@ static inline void instruction_pointer_set(struct pt_regs *regs, regs->psw.addr = val; } +unsigned long get_trap_ip(struct pt_regs *regs); + int regs_query_register_offset(const char *name); const char *regs_query_register_name(unsigned int offset); diff --git a/arch/s390/kernel/dis.c b/arch/s390/kernel/dis.c index 5a1a24d211c3..ece0b1e46ad4 100644 --- a/arch/s390/kernel/dis.c +++ b/arch/s390/kernel/dis.c @@ -503,7 +503,8 @@ static int copy_from_regs(struct pt_regs *regs, void *dst, void *src, int len) void show_code(struct pt_regs *regs) { char *mode = user_mode(regs) ? "User" : "Krnl"; - unsigned long addr, pswaddr; + unsigned long addr, pswaddr, trapaddr; + bool pgm_check; unsigned char code[64]; char buffer[128], *ptr; int start, end, opsize, hops, i; @@ -511,6 +512,9 @@ void show_code(struct pt_regs *regs) pswaddr = regs->psw.addr; if (test_pt_regs_flag(regs, PIF_PSW_ADDR_ADJUSTED)) pswaddr = __forward_psw(regs->psw, regs->int_code >> 16); + pgm_check = test_pt_regs_flag(regs, PIF_PGM_CHECK); + if (pgm_check) + trapaddr = get_trap_ip(regs); /* Get a snapshot of the 64 bytes surrounding the fault address. */ for (start = 32; start && pswaddr >= 34 - start; start -= 2) { addr = pswaddr - 34 + start; @@ -545,15 +549,17 @@ void show_code(struct pt_regs *regs) while (start < end && hops < 8) { ptr = buffer; opsize = insn_length(code[start]); + addr = pswaddr + start - 32; if (start == 32 && test_pt_regs_flag(regs, PIF_WARN_TRAP_SKIPPED)) ptr += sprintf(ptr, " WARN RET >"); - else if (start + opsize == 32 && !test_pt_regs_flag(regs, PIF_WARN_TRAP_SKIPPED)) - ptr += sprintf(ptr, " *"); + else if (pgm_check && addr == trapaddr && start == 32) + ptr += sprintf(ptr, " PGM+PSW >"); + else if (pgm_check && addr == trapaddr) + ptr += sprintf(ptr, " PGM >"); else if (start == 32) - ptr += sprintf(ptr, " >"); + ptr += sprintf(ptr, " PSW >"); else ptr += sprintf(ptr, " "); - addr = pswaddr + start - 32; ptr += sprintf(ptr, "%px: ", (void *)addr); if (start + opsize >= end) break; diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c index d875b3b304be..a603e034fa82 100644 --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -159,6 +159,7 @@ void __init __do_early_pgm_check(struct pt_regs *regs) regs->int_parm_long = lc->trans_exc_code; regs->last_break = lc->pgm_last_break; regs->monitor_code = lc->monitor_code; + set_pt_regs_flag(regs, PIF_PGM_CHECK); /* Monitor Event? Might be a warning */ if ((regs->int_code & PGM_INT_CODE_MASK) == 0x40) { diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c index 5e63032a56db..a0937b4a6cf3 100644 --- a/arch/s390/kernel/traps.c +++ b/arch/s390/kernel/traps.c @@ -42,7 +42,7 @@ struct pgm_stat { static DEFINE_PER_CPU_SHARED_ALIGNED(struct pgm_stat, pgm_stat); -static inline unsigned long get_trap_ip(struct pt_regs *regs) +unsigned long get_trap_ip(struct pt_regs *regs) { static const unsigned long nullified[2] = { PGM_CHECKS_NULLIFIED }; psw_t psw = regs->psw; @@ -56,6 +56,7 @@ static inline unsigned long get_trap_ip(struct pt_regs *regs) psw.addr = __rewind_psw(psw, regs->int_code >> 16); return psw.addr; } +NOKPROBE_SYMBOL(get_trap_ip); #ifdef CONFIG_GENERIC_BUG int is_valid_bugaddr(unsigned long addr) @@ -354,6 +355,7 @@ void noinstr __do_pgm_check(struct pt_regs *regs, unsigned long flags) regs->int_code = lc->pgm_int_code; regs->int_parm_long = teid.val; regs->monitor_code = lc->monitor_code; + set_pt_regs_flag(regs, PIF_PGM_CHECK); trapnr = regs->int_code & PGM_INT_CODE_MASK; stat = this_cpu_ptr(&pgm_stat); -- 2.53.0