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Date: Thu, 9 Aug 2012 17:48:17 +0200
From: Borislav Petkov <bp@...64.org>
To: LKML <linux-kernel@...r.kernel.org>, linux-arch@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Arnd Bergmann <arnd@...db.de>, Jan Beulich <jbeulich@...e.com>,
Frederic Weisbecker <fweisbec@...il.com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Josh Triplett <josh@...htriplett.org>
Subject: Re: [RFC PATCH] sysrq: Show architectural registers
On Thu, Aug 09, 2012 at 05:40:46PM +0200, Borislav Petkov wrote:
> From: Borislav Petkov <borislav.petkov@....com>
>
> One day I was playing with disabling the caches over CR0.CD and I wanted
> to check the current setting of the CD bit but there wasn't a way to do
> so from userspace because we #GP when accessing CR0.
>
> And then I thought, well, sysrq must have this. And it does:
>
> $ echo p > /proc/sysrq-trigger
>
> dumps the current registers. However, we don't dump the registers when
> we can't get the last exception frame through get_irq_regs().
>
> But, there are registers (CR0 included) which aren't in the exception
> frame and which can be dumped regardless. This patch does exactly that;
> with it, the output looks like this:
>
> [ 1759.206042] SysRq : Show Regs
> [ 1759.209194] FS: 00007fb1eada3700(0000) GS:ffff880c27c00000(0000) knlGS:0000000000000000
> [ 1759.217593] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1759.223554] CR2: 0000000000910390 CR3: 0000001020b48000 CR4: 00000000000007e0
> [ 1759.230956] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 1759.244974] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 1759.259052] CPU#18: active: 0000000000000000
> [ 1759.270539] CPU#18: gen-PMC0 ctrl: 0000030e011afcf6
> [ 1759.270543] CPU#18: gen-PMC0 count: 00009007d003b500
> [ 1759.270545] CPU#18: gen-PMC0 left: 0000000000000000
> [ 1759.270548] CPU#18: gen-PMC1 ctrl: 0000030f059b7efc
> [ 1759.270550] CPU#18: gen-PMC1 count: 00008003c823b4a0
> [ 1759.270552] CPU#18: gen-PMC1 left: 0000000000000000
> [ 1759.270555] CPU#18: gen-PMC2 ctrl: 00000104fe97c87c
> [ 1759.270557] CPU#18: gen-PMC2 count: 00007c6277e7f5fe
> [ 1759.270560] CPU#18: gen-PMC2 left: 0000000000000000
> [ 1759.270562] CPU#18: gen-PMC3 ctrl: 000000040000f0e2
> [ 1759.270564] CPU#18: gen-PMC3 count: 0000000000000000
> [ 1759.270566] CPU#18: gen-PMC3 left: 0000000000000000
>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Jan Beulich <jbeulich@...e.com>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> Cc: Josh Triplett <josh@...htriplett.org>
> Signed-off-by: Borislav Petkov <borislav.petkov@....com>
> ---
> arch/x86/include/asm/bug.h | 3 +++
> arch/x86/kernel/process_32.c | 43 ++++++++++++++++++++++------------------
> arch/x86/kernel/process_64.c | 47 ++++++++++++++++++++++++--------------------
> drivers/tty/sysrq.c | 1 +
> include/asm-generic/bug.h | 9 +++++++++
> 5 files changed, 63 insertions(+), 40 deletions(-)
>
> diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
> index 11e1152222d0..e60cf51fdfbd 100644
> --- a/arch/x86/include/asm/bug.h
> +++ b/arch/x86/include/asm/bug.h
> @@ -35,6 +35,9 @@ do { \
>
> #endif /* !CONFIG_BUG */
>
> +extern void _arch_show_regs(void);
> +#define _arch_show_regs _arch_show_regs
> +
> #include <asm-generic/bug.h>
>
>
> diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
> index 516fa186121b..6b01b6260f5d 100644
> --- a/arch/x86/kernel/process_32.c
> +++ b/arch/x86/kernel/process_32.c
> @@ -66,10 +66,32 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
> return ((unsigned long *)tsk->thread.sp)[3];
> }
>
> -void __show_regs(struct pt_regs *regs, int all)
> +void _arch_show_regs(void)
> {
> unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
> unsigned long d0, d1, d2, d3, d6, d7;
> +
> + cr0 = read_cr0();
> + cr2 = read_cr2();
> + cr3 = read_cr3();
> + cr4 = read_cr4_safe();
> + printk(KERN_DEFAULT "CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
> + cr0, cr2, cr3, cr4);
> +
> + get_debugreg(d0, 0);
> + get_debugreg(d1, 1);
> + get_debugreg(d2, 2);
> + get_debugreg(d3, 3);
> + printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
> + d0, d1, d2, d3);
> +
> + get_debugreg(d6, 6);
> + get_debugreg(d7, 7);
> + printk(KERN_DEFAULT "DR6: %08lx DR7: %08lx\n", d6, d7);
> +}
> +
> +void __show_regs(struct pt_regs *regs, int all)
> +{
> unsigned long sp;
> unsigned short ss, gs;
>
> @@ -100,24 +122,7 @@ void __show_regs(struct pt_regs *regs, int all)
> if (!all)
> return;
>
> - cr0 = read_cr0();
> - cr2 = read_cr2();
> - cr3 = read_cr3();
> - cr4 = read_cr4_safe();
> - printk(KERN_DEFAULT "CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
> - cr0, cr2, cr3, cr4);
> -
> - get_debugreg(d0, 0);
> - get_debugreg(d1, 1);
> - get_debugreg(d2, 2);
> - get_debugreg(d3, 3);
> - printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
> - d0, d1, d2, d3);
> -
> - get_debugreg(d6, 6);
> - get_debugreg(d7, 7);
> - printk(KERN_DEFAULT "DR6: %08lx DR7: %08lx\n",
> - d6, d7);
> + _arch_show_regs();
> }
>
> void release_thread(struct task_struct *dead_task)
> diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
> index 0a980c9d7cb8..dbe93bae6524 100644
> --- a/arch/x86/kernel/process_64.c
> +++ b/arch/x86/kernel/process_64.c
> @@ -54,30 +54,14 @@ asmlinkage extern void ret_from_fork(void);
>
> DEFINE_PER_CPU(unsigned long, old_rsp);
>
> -/* Prints also some state that isn't saved in the pt_regs */
> -void __show_regs(struct pt_regs *regs, int all)
> +/* Print also some state that isn't saved in the pt_regs */
> +void _arch_show_regs(void)
> {
> unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
> unsigned long d0, d1, d2, d3, d6, d7;
> unsigned int fsindex, gsindex;
> unsigned int ds, cs, es;
>
> - show_regs_common();
> - printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
> - printk_address(regs->ip, 1);
> - printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss,
> - regs->sp, regs->flags);
> - printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n",
> - regs->ax, regs->bx, regs->cx);
> - printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n",
> - regs->dx, regs->si, regs->di);
> - printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n",
> - regs->bp, regs->r8, regs->r9);
> - printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n",
> - regs->r10, regs->r11, regs->r12);
> - printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n",
> - regs->r13, regs->r14, regs->r15);
> -
> asm("movl %%ds,%0" : "=r" (ds));
> asm("movl %%cs,%0" : "=r" (cs));
> asm("movl %%es,%0" : "=r" (es));
> @@ -88,9 +72,6 @@ void __show_regs(struct pt_regs *regs, int all)
> rdmsrl(MSR_GS_BASE, gs);
> rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
>
> - if (!all)
> - return;
> -
> cr0 = read_cr0();
> cr2 = read_cr2();
> cr3 = read_cr3();
> @@ -113,6 +94,30 @@ void __show_regs(struct pt_regs *regs, int all)
> printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
> }
>
> +void __show_regs(struct pt_regs *regs, int all)
> +{
> + show_regs_common();
> + printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
> + printk_address(regs->ip, 1);
> + printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss,
> + regs->sp, regs->flags);
> + printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n",
> + regs->ax, regs->bx, regs->cx);
> + printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n",
> + regs->dx, regs->si, regs->di);
> + printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n",
> + regs->bp, regs->r8, regs->r9);
> + printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n",
> + regs->r10, regs->r11, regs->r12);
> + printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n",
> + regs->r13, regs->r14, regs->r15);
> +
> + if (!all)
> + return;
> +
> + _arch_show_regs();
> +}
> +
> void release_thread(struct task_struct *dead_task)
> {
> if (dead_task->mm) {
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index 05728894a88c..4ad0f884e08e 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -254,6 +254,7 @@ static void sysrq_handle_showregs(int key)
> struct pt_regs *regs = get_irq_regs();
> if (regs)
> show_regs(regs);
> + arch_show_regs();
> perf_event_print_debug();
> }
> static struct sysrq_key_op sysrq_showregs_op = {
Btw, this hunk should be:
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 05728894a88c..53dc73699882 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -254,6 +254,8 @@ static void sysrq_handle_showregs(int key)
struct pt_regs *regs = get_irq_regs();
if (regs)
show_regs(regs);
+ else
+ arch_show_regs();
perf_event_print_debug();
}
static struct sysrq_key_op sysrq_showregs_op = {
so as not to print the non-pt_regs registers twice.
Already fixed locally.
> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
> index 7d10f962aa13..e96d6c31c222 100644
> --- a/include/asm-generic/bug.h
> +++ b/include/asm-generic/bug.h
> @@ -202,6 +202,15 @@ extern void warn_slowpath_null(const char *file, const int line);
> # define WARN_ON_SMP(x) ({0;})
> #endif
>
> +#ifdef _arch_show_regs
> +static inline void arch_show_regs(void)
> +{
> + _arch_show_regs();
> +}
> +#else
> +static inline void arch_show_regs(void) { }
> +#endif
> +
> #endif /* __ASSEMBLY__ */
>
> #endif
> --
> 1.7.11.rc1
>
>
--
Regards/Gruss,
Boris.
Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551
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