From 6f367769e3979ac399078f3aea020f1bbe9a2f79 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 20 Feb 2015 10:58:59 +0100 Subject: s390/jump label: add missing jump_label_apply_nops() call When modules are loaded we want to transform the compile time generated nops into runtime generated nops. Otherwise the jump label sanity check will detect invalid code when trying to patch code. Fixes this crash: Jump label code mismatch at __rds_conn_create+0x3c/0x720 Found: c0 04 00 00 00 01 Expected: c0 04 00 00 00 00 Kernel panic - not syncing: Corrupted kernel text CPU: 0 PID: 10 Comm: migration/0 Not tainted 3.19.0-01935-g006610f #14 Call Trace: <0000000000113260> show_trace+0xf8/0x158) <000000000011332a> show_stack+0x6a/0xe8 <000000000069fd64> dump_stack+0x7c/0xd8 <0000000000698d54> panic+0xe4/0x288 <00000000006984c6> jump_label_bug.isra.2+0xbe/0xc001 <000000000011200c> __jump_label_transform+0x94/0xc8 Reported-by: Sebastian Ott Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/module.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/s390/kernel') diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c index 36154a2f1814..2ca95862e336 100644 --- a/arch/s390/kernel/module.c +++ b/arch/s390/kernel/module.c @@ -436,6 +436,7 @@ int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *me) { + jump_label_apply_nops(me); vfree(me->arch.syminfo); me->arch.syminfo = NULL; return 0; -- cgit v1.2.3 From 72dace969da8bf953915fd1776d6c15e7a41a675 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 20 Feb 2015 08:33:31 +0100 Subject: s390/jump label: improve and fix sanity check Fix the output of the jump label sanity check and also print the code pattern that is supposed to be written to the jump label. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/jump_label.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'arch/s390/kernel') diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c index cb2d51e779df..830066f936c8 100644 --- a/arch/s390/kernel/jump_label.c +++ b/arch/s390/kernel/jump_label.c @@ -36,16 +36,20 @@ static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn) insn->offset = (entry->target - entry->code) >> 1; } -static void jump_label_bug(struct jump_entry *entry, struct insn *insn) +static void jump_label_bug(struct jump_entry *entry, struct insn *expected, + struct insn *new) { unsigned char *ipc = (unsigned char *)entry->code; - unsigned char *ipe = (unsigned char *)insn; + unsigned char *ipe = (unsigned char *)expected; + unsigned char *ipn = (unsigned char *)new; pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc); pr_emerg("Found: %02x %02x %02x %02x %02x %02x\n", ipc[0], ipc[1], ipc[2], ipc[3], ipc[4], ipc[5]); pr_emerg("Expected: %02x %02x %02x %02x %02x %02x\n", ipe[0], ipe[1], ipe[2], ipe[3], ipe[4], ipe[5]); + pr_emerg("New: %02x %02x %02x %02x %02x %02x\n", + ipn[0], ipn[1], ipn[2], ipn[3], ipn[4], ipn[5]); panic("Corrupted kernel text"); } @@ -69,10 +73,10 @@ static void __jump_label_transform(struct jump_entry *entry, } if (init) { if (memcmp((void *)entry->code, &orignop, sizeof(orignop))) - jump_label_bug(entry, &old); + jump_label_bug(entry, &orignop, &new); } else { if (memcmp((void *)entry->code, &old, sizeof(old))) - jump_label_bug(entry, &old); + jump_label_bug(entry, &old, &new); } probe_kernel_write((void *)entry->code, &new, sizeof(new)); } -- cgit v1.2.3 From a9ca8eb7afb4f1c90d8e43092e94c4e86785efbc Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Sat, 28 Feb 2015 11:35:26 +0100 Subject: s390/ftrace: fix crashes when switching tracers / add notrace to cpu_relax() With git commit 4d92f50249eb ("s390: reintroduce diag 44 calls for cpu_relax()") I reintroduced a non-trivial cpu_relax() variant on s390. The difference to the previous variant however is that the new version is an out-of-line function, which will be traced if function tracing is enabled. Switching to different tracers includes instruction patching. Therefore this is done within stop_machine() "context" to prevent that any function tracing is going on while instructions are being patched. With the new out-of-line variant of cpu_relax() this is not true anymore, since cpu_relax() gets called in a busy loop by all waiting cpus within stop_machine() until function patching is finished. Therefore cpu_relax() must be marked notrace. This fixes kernel crashes when frequently switching between "function" and "function_graph" tracers. Moving cpu_relax() to a header file again, doesn't work because of header include order dependencies. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/processor.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/s390/kernel') diff --git a/arch/s390/kernel/processor.c b/arch/s390/kernel/processor.c index 26108232fcaa..dc488e13b7e3 100644 --- a/arch/s390/kernel/processor.c +++ b/arch/s390/kernel/processor.c @@ -18,7 +18,7 @@ static DEFINE_PER_CPU(struct cpuid, cpu_id); -void cpu_relax(void) +void notrace cpu_relax(void) { if (!smp_cpu_mtid && MACHINE_HAS_DIAG44) asm volatile("diag 0,0,0x44"); -- cgit v1.2.3