[reactos] 06/06: [NTOS:KDBG] Enhance the 'tss' command.

[Hermès Bélusca-Maïto]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=8826ee8ff7c77cbcb8c91…

commit 8826ee8ff7c77cbcb8c91cecc483cdc02e950e51
Author:     Hermès Bélusca-Maïto <hermes.belusca-maito(a)reactos.org>
AuthorDate: Sun Nov 3 03:44:55 2019 +0100
Commit:     Hermès Bélusca-Maïto <hermes.belusca-maito(a)reactos.org>
CommitDate: Sun Nov 3 05:08:40 2019 +0100

    [NTOS:KDBG] Enhance the 'tss' command.
    
    We allow specifying manually the TSS selector number or its descriptor address,
    and dump more information from the associated KTSS structure.
    
    Also add the KdbpRetrieveTss() helper to retrieve the PKTSS from its
    corresponding selector number. It will also be useful for future improvements.
---
 ntoskrnl/kdbg/kdb_cli.c | 147 +++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 134 insertions(+), 13 deletions(-)

diff --git a/ntoskrnl/kdbg/kdb_cli.c b/ntoskrnl/kdbg/kdb_cli.c
index d3d2a908997..fd93246afa7 100644
--- a/ntoskrnl/kdbg/kdb_cli.c
+++ b/ntoskrnl/kdbg/kdb_cli.c
@@ -178,7 +178,7 @@ static const struct
     { "ldt", "ldt", "Display the local descriptor table.",
KdbpCmdGdtLdtIdt },
     { "idt", "idt", "Display the interrupt descriptor
table.", KdbpCmdGdtLdtIdt },
     { "pcr", "pcr", "Display the processor control
region.", KdbpCmdPcr },
-    { "tss", "tss", "Display a task state segment.",
KdbpCmdTss },
+    { "tss", "tss [selector|*descaddr]", "Display the current
task state segment, or the one specified by its selector number or descriptor
address.", KdbpCmdTss },
 
     /* Others */
     { NULL, NULL, "Others", NULL },
@@ -987,6 +987,52 @@ KdbpCmdRegs(
     return TRUE;
 }
 
+static PKTSS
+KdbpRetrieveTss(
+    IN USHORT TssSelector,
+    OUT PULONG pType OPTIONAL,
+    IN PKDESCRIPTOR pGdtr OPTIONAL)
+{
+    KDESCRIPTOR Gdtr;
+    KGDTENTRY Desc;
+    PKTSS Tss;
+
+    /* Retrieve the Global Descriptor Table (user-provided or system) */
+    if (pGdtr)
+        Gdtr = *pGdtr;
+    else
+        Ke386GetGlobalDescriptorTable(&Gdtr.Limit);
+
+    /* Check limits */
+    if ((TssSelector & (sizeof(KGDTENTRY) - 1)) ||
+        (TssSelector < sizeof(KGDTENTRY)) ||
+        (TssSelector + sizeof(KGDTENTRY) - 1 > Gdtr.Limit))
+    {
+        return NULL;
+    }
+
+    /* Retrieve the descriptor */
+    if (!NT_SUCCESS(KdbpSafeReadMemory(&Desc,
+                                       (PVOID)(Gdtr.Base + TssSelector),
+                                       sizeof(KGDTENTRY))))
+    {
+        return NULL;
+    }
+
+    /* Check for TSS32(Avl) or TSS32(Busy) */
+    if (Desc.HighWord.Bits.Type != 9 && Desc.HighWord.Bits.Type != 11)
+    {
+        return NULL;
+    }
+    if (pType) *pType = Desc.HighWord.Bits.Type;
+
+    Tss = (PKTSS)(ULONG_PTR)(Desc.BaseLow |
+                             Desc.HighWord.Bytes.BaseMid << 16 |
+                             Desc.HighWord.Bytes.BaseHi << 24);
+
+    return Tss;
+}
+
 static BOOLEAN
 KdbpTrapFrameFromPrevTss(
     PKTRAP_FRAME TrapFrame)
@@ -2164,18 +2210,93 @@ KdbpCmdTss(
     ULONG Argc,
     PCHAR Argv[])
 {
-    KTSS *Tss = KeGetPcr()->TSS;
-
-    KdbpPrint("Current TSS is at 0x%p.\n", Tss);
-    KdbpPrint("  Eip:           0x%08x\n"
-              "  Es:            0x%04x\n"
-              "  Cs:            0x%04x\n"
-              "  Ss:            0x%04x\n"
-              "  Ds:            0x%04x\n"
-              "  Fs:            0x%04x\n"
-              "  Gs:            0x%04x\n"
-              "  IoMapBase:     0x%04x\n",
-              Tss->Eip, Tss->Es, Tss->Cs, Tss->Ds, Tss->Fs, Tss->Gs,
Tss->IoMapBase);
+    USHORT TssSelector;
+    PKTSS Tss = NULL;
+
+    if (Argc >= 2)
+    {
+        /*
+         * Specified TSS via its selector [selector] or descriptor address [*descaddr].
+         * Note that we ignore any other argument values.
+         */
+        PCHAR Param, pszNext;
+        ULONG ulValue;
+
+        Param = Argv[1];
+        if (Argv[1][0] == '*')
+            ++Param;
+
+        ulValue = strtoul(Param, &pszNext, 0);
+        if (pszNext && *pszNext)
+        {
+            KdbpPrint("Invalid TSS specification.\n");
+            return TRUE;
+        }
+
+        if (Argv[1][0] == '*')
+        {
+            /* Descriptor specified */
+            TssSelector = 0; // Unknown selector!
+            // TODO: Room for improvement: Find the TSS descriptor
+            // in the GDT so as to validate it.
+            Tss = (PKTSS)(ULONG_PTR)ulValue;
+            if (!Tss)
+            {
+                KdbpPrint("Invalid 32-bit TSS descriptor.\n");
+                return TRUE;
+            }
+        }
+        else
+        {
+            /* Selector specified, retrive the corresponding TSS */
+            TssSelector = (USHORT)ulValue;
+            Tss = KdbpRetrieveTss(TssSelector, NULL, NULL);
+            if (!Tss)
+            {
+                KdbpPrint("Invalid 32-bit TSS selector.\n");
+                return TRUE;
+            }
+        }
+    }
+
+    if (!Tss)
+    {
+        /* If no TSS was specified, use the current TSS descriptor */
+        TssSelector = Ke386GetTr();
+        Tss = KeGetPcr()->TSS;
+        // NOTE: If everything works OK, Tss is the current TSS corresponding to the TR
selector.
+    }
+
+    KdbpPrint("%s TSS 0x%04x is at 0x%p.\n",
+              (Tss == KeGetPcr()->TSS) ? "Current" : "Specified",
TssSelector, Tss);
+    KdbpPrint("  Backlink:  0x%04x\n"
+              "  Ss0:Esp0:  0x%04x:0x%08x\n"
+              // NOTE: Ss1:Esp1 and Ss2:Esp2: are in the NotUsed1 field.
+              "  CR3:       0x%08x\n"
+              "  EFlags:    0x%08x\n"
+              "  Eax:       0x%08x\n"
+              "  Ebx:       0x%08x\n"
+              "  Ecx:       0x%08x\n"
+              "  Edx:       0x%08x\n"
+              "  Esi:       0x%08x\n"
+              "  Edi:       0x%08x\n"
+              "  Eip:       0x%08x\n"
+              "  Esp:       0x%08x\n"
+              "  Ebp:       0x%08x\n"
+              "  Cs:        0x%04x\n"
+              "  Ss:        0x%04x\n"
+              "  Ds:        0x%04x\n"
+              "  Es:        0x%04x\n"
+              "  Fs:        0x%04x\n"
+              "  Gs:        0x%04x\n"
+              "  LDT:       0x%04x\n"
+              "  Flags:     0x%04x\n"
+              "  IoMapBase: 0x%04x\n",
+              Tss->Backlink, Tss->Ss0, Tss->Esp0, Tss->CR3, Tss->EFlags,
+              Tss->Eax, Tss->Ebx, Tss->Ecx, Tss->Edx, Tss->Esi,
Tss->Edi,
+              Tss->Eip, Tss->Esp, Tss->Ebp,
+              Tss->Cs, Tss->Ss, Tss->Ds, Tss->Es, Tss->Fs, Tss->Gs,
+              Tss->LDT, Tss->Flags, Tss->IoMapBase);
 
     return TRUE;
 }