From b0529becebde629ff6abf2afdca6def6824f4fa9 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 11 Jul 2017 10:33:40 -0500 Subject: x86/dumpstack: Fix occasionally missing registers If two consecutive stack frames have pt_regs, the oops dump code fails to print the second frame's registers. Fix that. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jiri Slaby Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: live-patching@vger.kernel.org Fixes: 3b3fa11bc700 ("x86/dumpstack: Print any pt_regs found on the stack") Link: http://lkml.kernel.org/r/269c5c00c7d45c699f3dcea42a3a594c6cf7a9a3.1499786555.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'arch/x86/kernel/dumpstack.c') diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index dbce3cca94cb..bd265a4cf108 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -94,6 +94,9 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, if (stack_name) printk("%s <%s>\n", log_lvl, stack_name); + if (regs && on_stack(&stack_info, regs, sizeof(*regs))) + __show_regs(regs, 0); + /* * Scan the stack, printing any text addresses we find. At the * same time, follow proper stack frames with the unwinder. @@ -118,10 +121,8 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, * Don't print regs->ip again if it was already printed * by __show_regs() below. */ - if (regs && stack == ®s->ip) { - unwind_next_frame(&state); - continue; - } + if (regs && stack == ®s->ip) + goto next; if (stack == ret_addr_p) reliable = 1; @@ -144,6 +145,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, if (!reliable) continue; +next: /* * Get the next frame from the unwinder. No need to * check for an error: if anything goes wrong, the rest @@ -153,7 +155,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, /* if the frame has entry regs, print them */ regs = unwind_get_entry_regs(&state); - if (regs) + if (regs && on_stack(&stack_info, regs, sizeof(*regs))) __show_regs(regs, 0); } -- cgit v1.2.3 From 99504819fc643160afd6813921b1d42b18e52a49 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Fri, 28 Jul 2017 06:00:32 -0700 Subject: x86/asm/32: Remove a bunch of '& 0xffff' from pt_regs segment reads Now that pt_regs properly defines segment fields as 16-bit on 32-bit CPUs, there's no need to mask off the high word. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- arch/x86/ia32/ia32_signal.c | 2 +- arch/x86/include/asm/elf.h | 10 +++++----- arch/x86/kernel/dumpstack.c | 2 +- arch/x86/kernel/process_32.c | 2 +- arch/x86/kernel/process_64.c | 3 +-- arch/x86/kernel/signal.c | 2 +- arch/x86/kernel/step.c | 2 +- arch/x86/mm/extable.c | 2 +- 8 files changed, 12 insertions(+), 13 deletions(-) (limited to 'arch/x86/kernel/dumpstack.c') diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index 724153797209..e0bb46c02857 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -226,7 +226,7 @@ static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, if (ksig->ka.sa.sa_flags & SA_ONSTACK) sp = sigsp(sp, ksig); /* This is the legacy signal stack switching. */ - else if ((regs->ss & 0xffff) != __USER32_DS && + else if (regs->ss != __USER32_DS && !(ksig->ka.sa.sa_flags & SA_RESTORER) && ksig->ka.sa.sa_restorer) sp = (unsigned long) ksig->ka.sa.sa_restorer; diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 1c18d83d3f09..a62a12c47233 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -126,15 +126,15 @@ do { \ pr_reg[4] = regs->di; \ pr_reg[5] = regs->bp; \ pr_reg[6] = regs->ax; \ - pr_reg[7] = regs->ds & 0xffff; \ - pr_reg[8] = regs->es & 0xffff; \ - pr_reg[9] = regs->fs & 0xffff; \ + pr_reg[7] = regs->ds; \ + pr_reg[8] = regs->es; \ + pr_reg[9] = regs->fs; \ pr_reg[11] = regs->orig_ax; \ pr_reg[12] = regs->ip; \ - pr_reg[13] = regs->cs & 0xffff; \ + pr_reg[13] = regs->cs; \ pr_reg[14] = regs->flags; \ pr_reg[15] = regs->sp; \ - pr_reg[16] = regs->ss & 0xffff; \ + pr_reg[16] = regs->ss; \ } while (0); #define ELF_CORE_COPY_REGS(pr_reg, regs) \ diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index bd265a4cf108..f13b4c00a5de 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -267,7 +267,7 @@ int __die(const char *str, struct pt_regs *regs, long err) #ifdef CONFIG_X86_32 if (user_mode(regs)) { sp = regs->sp; - ss = regs->ss & 0xffff; + ss = regs->ss; } else { sp = kernel_stack_pointer(regs); savesegment(ss, ss); diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index c6d6dc5f8bb2..efc5eeb58292 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -68,7 +68,7 @@ void __show_regs(struct pt_regs *regs, int all) if (user_mode(regs)) { sp = regs->sp; - ss = regs->ss & 0xffff; + ss = regs->ss; gs = get_user_gs(regs); } else { sp = kernel_stack_pointer(regs); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 2987e3991c2b..e04941fb67fb 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -69,8 +69,7 @@ void __show_regs(struct pt_regs *regs, int all) unsigned int fsindex, gsindex; unsigned int ds, cs, es; - printk(KERN_DEFAULT "RIP: %04lx:%pS\n", regs->cs & 0xffff, - (void *)regs->ip); + printk(KERN_DEFAULT "RIP: %04lx:%pS\n", regs->cs, (void *)regs->ip); printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx", regs->ss, regs->sp, regs->flags); if (regs->orig_ax != -1) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index cc30a74e4adb..e04442345fc0 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -256,7 +256,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, sp = current->sas_ss_sp + current->sas_ss_size; } else if (IS_ENABLED(CONFIG_X86_32) && !onsigstack && - (regs->ss & 0xffff) != __USER_DS && + regs->ss != __USER_DS && !(ka->sa.sa_flags & SA_RESTORER) && ka->sa.sa_restorer) { /* This is the legacy signal stack switching. */ diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index 5f25cfbd952e..5ee663836c08 100644 --- a/arch/x86/kernel/step.c +++ b/arch/x86/kernel/step.c @@ -13,7 +13,7 @@ unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *re unsigned long addr, seg; addr = regs->ip; - seg = regs->cs & 0xffff; + seg = regs->cs; if (v8086_mode(regs)) { addr = (addr & 0xffff) + (seg << 4); return addr; diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 0ea8afcb929c..fb2ddcdf7c73 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -142,7 +142,7 @@ void __init early_fixup_exception(struct pt_regs *regs, int trapnr) * undefined. I'm not sure which CPUs do this, but at least * the 486 DX works this way. */ - if ((regs->cs & 0xFFFF) != __KERNEL_CS) + if (regs->cs != __KERNEL_CS) goto fail; /* -- cgit v1.2.3