Jordan Crouse wrote:
> Can you break this up with a : between the high dword and the low dword?
> That makes it easier to parse when debugging.
Good idea, but I used "_" instead because it's what AMD uses in their
documentation and it looks better with a "0x" prefix.
> Also, would it make sense to coordinate the order of the high and low
> dwords with the order they are specified with 'wrmsr'?
Yeah, I did it as suggested by Mitch. Here's a thrid
revision of the patch with everything included:
>From 1850ca76585306e2484cf5e709434049f1df3c1f Mon Sep 17 00:00:00 2001
From: Bernardo Innocenti <[email protected]>
Date: Tue, 15 May 2007 15:29:48 -0400
Subject: [PATCH] kdb: add rdmsr and wrmsr commands for i386 (take 3)
The syntax is:
rdmsr <addr>
wrmsr <addr> <h> <l>
Signed-off-by: Bernardo Innocenti <[email protected]>
---
arch/i386/kdb/kdbasupport.c | 47 +++++++++++++++++++++++++++++++++++++++---
kdb/kdbmain.c | 3 +-
2 files changed, 44 insertions(+), 6 deletions(-)
diff --git a/arch/i386/kdb/kdbasupport.c b/arch/i386/kdb/kdbasupport.c
index 482b319..7038dfb 100644
--- a/arch/i386/kdb/kdbasupport.c
+++ b/arch/i386/kdb/kdbasupport.c
@@ -223,6 +223,46 @@ kdba_removedbreg(kdb_bp_t *bp)
kdba_putdr7(dr7);
}
+static int
+kdba_rdmsr(int argc, const char **argv)
+{
+ unsigned long addr;
+ uint32_t l, h;
+ int diag;
+
+ if (argc != 1)
+ return KDB_ARGCOUNT;
+
+ if ((diag = kdbgetularg(argv[1], &addr)))
+ return diag;
+
+ kdb_printf("msr(0x%lx) = ", addr);
+ rdmsr(addr, l, h);
+ kdb_printf("0x%08lx_%08lx\n", h, l);
+
+ return 0;
+}
+
+static int
+kdba_wrmsr(int argc, const char **argv)
+{
+ unsigned long addr;
+ unsigned long l, h;
+ int diag;
+
+ if (argc != 3)
+ return KDB_ARGCOUNT;
+
+ if ((diag = kdbgetularg(argv[1], &addr))
+ || (diag = kdbgetularg(argv[2], &h))
+ || (diag = kdbgetularg(argv[3], &l)))
+ return diag;
+
+ wrmsr(addr, l, h);
+
+ return 0;
+}
+
/*
* kdba_getregcontents
@@ -474,12 +514,11 @@ kdba_setregcontents(const char *regname,
* argument is NULL (struct pt_regs). The alternate register
* set types supported by this function:
*
- * d Debug registers
+ * d Debug registers
* c Control registers
* u User registers at most recent entry to kernel
* for the process currently selected with "pid" command.
* Following not yet implemented:
- * m Model Specific Registers (extra defines register #)
* r Memory Type Range Registers (extra defines register)
*/
@@ -546,8 +585,6 @@ kdba_dumpregs(struct pt_regs *regs,
cr[0], cr[1], cr[2], cr[3], cr[4]);
return 0;
}
- case 'm':
- break;
case 'r':
break;
default:
@@ -899,6 +936,8 @@ kdba_init(void)
{
kdb_register("pt_regs", kdba_pt_regs, "address", "Format struct pt_regs", 0);
kdb_register("stackdepth", kdba_stackdepth, "[percentage]", "Print processes using >= stack percentage", 0);
+ kdb_register("rdmsr", kdba_rdmsr, "<maddr>", "Display Model Specific Register", 0);
+ kdb_register("wrmsr", kdba_wrmsr, "<maddr> <h> <l>", "Modify Model Specific Register", 0);
return;
}
diff --git a/kdb/kdbmain.c b/kdb/kdbmain.c
index 0b2cb91..88bf14f 100644
--- a/kdb/kdbmain.c
+++ b/kdb/kdbmain.c
@@ -2596,8 +2596,7 @@ kdb_rd(int argc, const char **argv)
* none.
* Remarks:
* Currently doesn't allow modification of control or
- * debug registers, nor does it allow modification
- * of model-specific registers (MSR).
+ * debug registers.
*/
static int
--
1.5.0.2
--
// Bernardo Innocenti
\X/ http://www.codewiz.org/
Bernardo Innocenti (on Tue, 15 May 2007 23:03:55 -0400) wrote:
>Jordan Crouse wrote:
>
>> Can you break this up with a : between the high dword and the low dword?
>> That makes it easier to parse when debugging.
>
>Good idea, but I used "_" instead because it's what AMD uses in their
>documentation and it looks better with a "0x" prefix.
>
>> Also, would it make sense to coordinate the order of the high and low
>> dwords with the order they are specified with 'wrmsr'?
>
>Yeah, I did it as suggested by Mitch. Here's a thrid
>revision of the patch with everything included:
>
>From 1850ca76585306e2484cf5e709434049f1df3c1f Mon Sep 17 00:00:00 2001
>From: Bernardo Innocenti <[email protected]>
>Date: Tue, 15 May 2007 15:29:48 -0400
>Subject: [PATCH] kdb: add rdmsr and wrmsr commands for i386 (take 3)
>
>The syntax is:
> rdmsr <addr>
> wrmsr <addr> <h> <l>
>
>Signed-off-by: Bernardo Innocenti <[email protected]>
>---
> arch/i386/kdb/kdbasupport.c | 47 +++++++++++++++++++++++++++++++++++++++---
> kdb/kdbmain.c | 3 +-
Thanks for the patch, but ...
Before using MSR, you must first check that the cpu supports the
instruction, rd/wrmsr cause an oops on 486 or earlier. Also using an
invalid msr number causes an oops, so use rd/wrmsr_safe(). Finally, kdb
on x86_64 needs the commands as well, so move it to kdb/modules/kdbm_x86.c
(common i386/x86_64 code). Cleaned up patch + changelogs.
---
arch/i386/kdb/ChangeLog | 6 ++++
arch/i386/kdb/kdbasupport.c | 7 ++--
arch/x86_64/kdb/ChangeLog | 6 ++++
arch/x86_64/kdb/kdbasupport.c | 7 ++--
kdb/ChangeLog | 7 ++++
kdb/kdbmain.c | 3 --
kdb/modules/kdbm_x86.c | 59 ++++++++++++++++++++++++++++++++++++++++++
7 files changed, 85 insertions(+), 10 deletions(-)
diff -u linux/arch/i386/kdb/ChangeLog linux/arch/i386/kdb/ChangeLog
--- linux/arch/i386/kdb/ChangeLog
+++ linux/arch/i386/kdb/ChangeLog
@@ -1,3 +1,9 @@
+2007-05-17 Keith Owens <[email protected]>
+
+ * Update dumpregs comments for rdmsr and wrmsr commands.
+ Bernardo Innocenti.
+ * kdb v4.4-2.6.21-i386-3.
+
2007-05-15 Keith Owens <[email protected]>
* Change kdba_late_init to kdba_arch_init so KDB_ENTER() can be used
diff -u linux/arch/i386/kdb/kdbasupport.c linux/arch/i386/kdb/kdbasupport.c
--- linux/arch/i386/kdb/kdbasupport.c
+++ linux/arch/i386/kdb/kdbasupport.c
@@ -474,13 +474,14 @@
* argument is NULL (struct pt_regs). The alternate register
* set types supported by this function:
*
- * d Debug registers
+ * d Debug registers
* c Control registers
* u User registers at most recent entry to kernel
* for the process currently selected with "pid" command.
* Following not yet implemented:
- * m Model Specific Registers (extra defines register #)
* r Memory Type Range Registers (extra defines register)
+ *
+ * MSR on i386/x86_64 are handled by rdmsr/wrmsr commands.
*/
int
@@ -546,8 +547,6 @@
cr[0], cr[1], cr[2], cr[3], cr[4]);
return 0;
}
- case 'm':
- break;
case 'r':
break;
default:
diff -u linux/arch/x86_64/kdb/ChangeLog linux/arch/x86_64/kdb/ChangeLog
--- linux/arch/x86_64/kdb/ChangeLog
+++ linux/arch/x86_64/kdb/ChangeLog
@@ -1,3 +1,9 @@
+2007-05-17 Keith Owens <[email protected]>
+
+ * Update dumpregs comments for rdmsr and wrmsr commands.
+ Bernardo Innocenti.
+ * kdb v4.4-2.6.21-x86_64-3.
+
2007-05-15 Keith Owens <[email protected]>
* Change kdba_late_init to kdba_arch_init so KDB_ENTER() can be used
diff -u linux/arch/x86_64/kdb/kdbasupport.c linux/arch/x86_64/kdb/kdbasupport.c
--- linux/arch/x86_64/kdb/kdbasupport.c
+++ linux/arch/x86_64/kdb/kdbasupport.c
@@ -470,12 +470,13 @@
* argument is NULL (struct pt_regs). The alternate register
* set types supported by this function:
*
- * d Debug registers
+ * d Debug registers
* c Control registers
* u User registers at most recent entry to kernel
* Following not yet implemented:
- * m Model Specific Registers (extra defines register #)
* r Memory Type Range Registers (extra defines register)
+ *
+ * MSR on i386/x86_64 are handled by rdmsr/wrmsr commands.
*/
int
@@ -536,8 +537,6 @@
cr[0], cr[1], cr[2], cr[3], cr[4]);
return 0;
}
- case 'm':
- break;
case 'r':
break;
default:
diff -u linux/kdb/ChangeLog linux/kdb/ChangeLog
--- linux/kdb/ChangeLog
+++ linux/kdb/ChangeLog
@@ -1,3 +1,10 @@
+2007-05-17 Keith Owens <[email protected]>
+
+ * Add rdmsr and wrmsr commands for i386 and x86_64. Original patch by
+ Bernardo Innocenti for i386, reworked by Keith Owens to make it safe
+ on all cpu models and to handle both i386 and x86_64.
+ * kdb v4.4-2.6.21-common-3.
+
2007-05-15 Keith Owens <[email protected]>
* Correct alignment of debug_alloc_header.
diff -u linux/kdb/kdbmain.c linux/kdb/kdbmain.c
--- linux/kdb/kdbmain.c
+++ linux/kdb/kdbmain.c
@@ -2596,8 +2596,7 @@
* none.
* Remarks:
* Currently doesn't allow modification of control or
- * debug registers, nor does it allow modification
- * of model-specific registers (MSR).
+ * debug registers.
*/
static int
diff -u linux/kdb/modules/kdbm_x86.c linux/kdb/modules/kdbm_x86.c
--- linux/kdb/modules/kdbm_x86.c
+++ linux/kdb/modules/kdbm_x86.c
@@ -1012,6 +1012,61 @@
return 0;
}
+static int
+kdb_rdmsr(int argc, const char **argv)
+{
+ unsigned long addr;
+ uint32_t l, h;
+ int diag;
+ struct cpuinfo_x86 *c = cpu_data + smp_processor_id();
+
+ if (argc != 1)
+ return KDB_ARGCOUNT;
+
+ if ((diag = kdbgetularg(argv[1], &addr)))
+ return diag;
+
+ if (!cpu_has(c, X86_FEATURE_MSR))
+ return KDB_NOTIMP;
+
+ kdb_printf("msr(0x%lx) = ", addr);
+ if ((diag = rdmsr_safe(addr, &l, &h))) {
+ kdb_printf("error %d\n", diag);
+ return KDB_BADINT;
+ } else {
+ kdb_printf("0x%08x_%08x\n", h, l);
+ }
+
+ return 0;
+}
+
+static int
+kdb_wrmsr(int argc, const char **argv)
+{
+ unsigned long addr;
+ unsigned long l, h;
+ int diag;
+ struct cpuinfo_x86 *c = cpu_data + smp_processor_id();
+
+ if (argc != 3)
+ return KDB_ARGCOUNT;
+
+ if ((diag = kdbgetularg(argv[1], &addr))
+ || (diag = kdbgetularg(argv[2], &h))
+ || (diag = kdbgetularg(argv[3], &l)))
+ return diag;
+
+ if (!cpu_has(c, X86_FEATURE_MSR))
+ return KDB_NOTIMP;
+
+ if ((diag = wrmsr_safe(addr, l, h))) {
+ kdb_printf("error %d\n", diag);
+ return KDB_BADINT;
+ }
+
+ return 0;
+}
+
static int __init kdbm_x86_init(void)
{
kdb_register("rdv", kdb_rdv, NULL, "Display registers in verbose mode", 0);
@@ -1020,6 +1075,8 @@
kdb_register_repeat("ldt", kdb_ldt, "<sel> [<count>]", "Display LDT", 0, KDB_REPEAT_NO_ARGS);
kdb_register_repeat("ptex", kdb_pte, "<addr> [<count>]", "Display pagetables", 0, KDB_REPEAT_NO_ARGS);
kdb_register_repeat("ldtp", kdb_ldt, "<sel> [<count>]", "Display Process LDT", 0, KDB_REPEAT_NO_ARGS);
+ kdb_register("rdmsr", kdb_rdmsr, "<maddr>", "Display Model Specific Register", 0);
+ kdb_register("wrmsr", kdb_wrmsr, "<maddr> <h> <l>", "Modify Model Specific Register", 0);
return 0;
}
@@ -1031,6 +1088,8 @@
kdb_unregister("idt");
kdb_unregister("ptex");
kdb_unregister("ldtp");
+ kdb_unregister("rdmsr");
+ kdb_unregister("wrmsr");
}
module_init(kdbm_x86_init)
Keith Owens wrote:
> Before using MSR, you must first check that the cpu supports the
> instruction, rd/wrmsr cause an oops on 486 or earlier. Also using an
> invalid msr number causes an oops, so use rd/wrmsr_safe().
I didn't bother implementing those checks because kdb recovers
nicely from GPF anyway. It's the valid MSR writes that could
cause unrecoveable problems! :)
--
// Bernardo Innocenti
\X/ http://www.codewiz.org/
Bernardo Innocenti (on Thu, 17 May 2007 02:36:21 -0400) wrote:
>Keith Owens wrote:
>
>> Before using MSR, you must first check that the cpu supports the
>> instruction, rd/wrmsr cause an oops on 486 or earlier. Also using an
>> invalid msr number causes an oops, so use rd/wrmsr_safe().
>
>I didn't bother implementing those checks because kdb recovers
>nicely from GPF anyway.
Yes and no. Yes, kdb will recover from a GPF. No, because if the
system was already running correctly (i.e. manual entry into kdb), then
taking a GPF and not recovering will flag the rest of the system as
corrupt and can kill a running system. I try to avoid adding spurious
system corruption.
>It's the valid MSR writes that could
>cause unrecoveable problems! :)
Tell me about it :-(