2 // Low leve x64 specific debug support functions.
4 // Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
5 // Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
6 // This program and the accompanying materials
7 // are licensed and made available under the terms and conditions of the BSD License
8 // which accompanies this distribution. The full text of the license may be found at
9 // http://opensource.org/licenses/bsd-license.php
11 // THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
16 ASM_GLOBAL ASM_PFX(OrigVector)
17 ASM_GLOBAL ASM_PFX(InterruptEntryStub)
18 ASM_GLOBAL ASM_PFX(StubSize)
19 ASM_GLOBAL ASM_PFX(CommonIdtEntry)
20 ASM_GLOBAL ASM_PFX(FxStorSupport)
24 ASM_PFX(StubSize): .long ASM_PFX(InterruptEntryStubEnd) - ASM_PFX(InterruptEntryStub)
25 ASM_PFX(AppRsp): .long 0x11111111 # ?
27 ASM_PFX(DebugRsp): .long 0x22222222 # ?
29 ASM_PFX(ExtraPush): .long 0x33333333 # ?
31 ASM_PFX(ExceptData): .long 0x44444444 # ?
33 ASM_PFX(Rflags): .long 0x55555555 # ?
35 ASM_PFX(OrigVector): .long 0x66666666 # ?
38 // The declarations below define the memory region that will be used for the debug stack.
39 // The context record will be built by pushing register values onto this stack.
40 // It is imparitive that alignment be carefully managed, since the FXSTOR and
41 // FXRSTOR instructions will GP fault if their memory operand is not 16 byte aligned.
43 // The stub will switch stacks from the application stack to the debuger stack
44 // and pushes the exception number.
46 // Then we building the context record on the stack. Since the stack grows down,
47 // we push the fields of the context record from the back to the front. There
48 // are 336 bytes of stack used prior allocating the 512 bytes of stack to be
49 // used as the memory buffer for the fxstor instruction. Therefore address of
50 // the buffer used for the FXSTOR instruction is &Eax - 336 - 512, which
51 // must be 16 byte aligned.
53 // We carefully locate the stack to make this happen.
55 // For reference, the context structure looks like this:
57 // UINT64 ExceptionData;
58 // FX_SAVE_STATE_X64 FxSaveState; // 512 bytes, must be 16 byte aligned
59 // UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
60 // UINT64 Cr0, Cr1, Cr2, Cr3, Cr4, Cr8;
63 // UINT64 Gdtr[2], Idtr[2];
65 // UINT64 Gs, Fs, Es, Ds, Cs, Ss;
66 // UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
67 // UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
68 // } SYSTEM_CONTEXT_X64; // 64 bit system context record
71 DebugStackEnd : .ascii "DbgStkEnd >>>>>>" # 16 byte long string - must be 16 bytes to preserve alignment
72 .fill 0x1ffc, 4, 0x00000000
73 # 32K should be enough stack
74 # This allocation is coocked to insure
75 # that the the buffer for the FXSTORE instruction
76 # will be 16 byte aligned also.
78 ASM_PFX(ExceptionNumber): .long 0x77777777 # first entry will be the vector number pushed by the stub
81 DebugStackBegin : .ascii "<<<< DbgStkBegin" # initial debug ESP == DebugStackBegin, set in stub
86 //------------------------------------------------------------------------------
92 // Abstract: Returns TRUE if FxStor instructions are supported
94 ASM_GLOBAL ASM_PFX(FxStorSupport)
95 ASM_PFX(FxStorSupport):
97 // cpuid corrupts rbx which must be preserved per the C calling convention
103 andq $0x01000000, %rax
107 //------------------------------------------------------------------------------
110 // IA32_IDT_GATE_DESCRIPTOR * DestDesc, // rcx
111 // void (*Vector) (void) // rdx
114 // Abstract: Encodes an IDT descriptor with the given physical address
116 ASM_GLOBAL ASM_PFX(Vect2Desc)
119 movw %ax, (%rcx) # write bits 15..0 of offset
121 movw %dx, 2(%rcx) # SYS_CODE_SEL from GDT
122 movw $(0x0e00 | 0x8000), 4(%rcx) # type = 386 interrupt gate, present
124 movw %ax, 6(%rcx) # write bits 31..16 of offset
126 movl %eax, 8(%rcx) # write bits 63..32 of offset
130 //------------------------------------------------------------------------------
131 // InterruptEntryStub
133 // Abstract: This code is not a function, but is a small piece of code that is
134 // copied and fixed up once for each IDT entry that is hooked.
136 ASM_GLOBAL ASM_PFX(InterruptEntryStub)
137 ASM_PFX(InterruptEntryStub):
139 pushq $0 # push vector number - will be modified before installed
140 jmp ASM_PFX(CommonIdtEntry)
142 ASM_GLOBAL ASM_PFX(InterruptEntryStubEnd)
143 ASM_PFX(InterruptEntryStubEnd):
145 //------------------------------------------------------------------------------
148 // Abstract: This code is not a function, but is the common part for all IDT
151 ASM_GLOBAL ASM_PFX(CommonIdtEntry)
153 // At this point, the stub has saved the current application stack esp into AppRsp
154 // and switched stacks to the debug stack, where it pushed the vector number
156 // The application stack looks like this:
159 // (last application stack entry)
160 // [16 bytes alignment, do not care it]
161 // SS from interrupted task
162 // RSP from interrupted task
163 // rflags from interrupted task
164 // CS from interrupted task
165 // RIP from interrupted task
166 // Error code <-------------------- Only present for some exeption types
168 // Vector Number <----------------- pushed in our IDT Entry
172 // The stub switched us to the debug stack and pushed the interrupt number.
174 // Next, construct the context record. It will be build on the debug stack by
175 // pushing the registers in the correct order so as to create the context structure
176 // on the debug stack. The context record must be built from the end back to the
177 // beginning because the stack grows down...
179 // For reference, the context record looks like this:
183 // UINT64 ExceptionData;
184 // FX_SAVE_STATE_X64 FxSaveState;
185 // UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
186 // UINT64 Cr0, Cr2, Cr3, Cr4, Cr8;
189 // UINT64 Gdtr[2], Idtr[2];
191 // UINT64 Gs, Fs, Es, Ds, Cs, Ss;
192 // UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
193 // UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
194 // } SYSTEM_CONTEXT_X64; // 64
195 ASM_PFX(CommonIdtEntry):
196 // NOTE: we save rsp here to prevent compiler put rip reference cause error AppRsp
198 movq (8)(%rsp), %rax # save vector number
199 movq %rax, ASM_PFX(ExceptionNumber)(%rip) # save vector number
201 addq $8, %rsp # pop vector number
202 movq %rsp, ASM_PFX(AppRsp)(%rip) # save stack top
203 movq DebugStackBegin(%rip), %rsp # switch to debugger stack
204 subq $8, %rsp # leave space for vector number
205 // UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
206 // UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
223 // Save interrupt state rflags register...
226 movq %rax, ASM_PFX(Rflags)(%rip)
227 // We need to determine if any extra data was pushed by the exception, and if so, save it
228 // To do this, we check the exception number pushed by the stub, and cache the
229 // result in a variable since we'll need this again.
230 cmpl $0, ASM_PFX(ExceptionNumber)(%rip)
232 cmpl $10, ASM_PFX(ExceptionNumber)(%rip)
234 cmpl $11, ASM_PFX(ExceptionNumber)(%rip)
236 cmpl $12, ASM_PFX(ExceptionNumber)(%rip)
238 cmpl $13, ASM_PFX(ExceptionNumber)(%rip)
240 cmpl $14, ASM_PFX(ExceptionNumber)(%rip)
242 cmpl $17, ASM_PFX(ExceptionNumber)(%rip)
244 movl $0, ASM_PFX(ExtraPush)(%rip)
245 movl $0, ASM_PFX(ExceptData)(%rip)
248 movl $1, ASM_PFX(ExtraPush)(%rip)
250 // If there's some extra data, save it also, and modify the saved AppRsp to effectively
251 // pop this value off the application's stack.
252 movq ASM_PFX(AppRsp)(%rip), %rax
254 movq %rbx, ASM_PFX(ExceptData)(%rip)
256 movq %rax, ASM_PFX(AppRsp)(%rip)
260 // The "push" above pushed the debug stack rsp. Since what we're actually doing
261 // is building the context record on the debug stack, we need to save the pushed
262 // debug RSP, and replace it with the application's last stack entry...
264 movq %rax, ASM_PFX(DebugRsp)(%rip)
265 movq ASM_PFX(AppRsp)(%rip), %rax
267 # application stack has ss, rsp, rflags, cs, & rip, so
268 # last actual application stack entry is saved at offset
269 # 24 bytes from stack top.
272 // continue building context record
273 // UINT64 Gs, Fs, Es, Ds, Cs, Ss; insure high 16 bits of each is zero
276 # CS from application is one entry back in application stack
277 movq ASM_PFX(AppRsp)(%rip), %rax
290 # Rip from application is on top of application stack
291 movq ASM_PFX(AppRsp)(%rip), %rax
293 // UINT64 Gdtr[2], Idtr[2];
309 // Rflags from application is two entries back in application stack
310 movq ASM_PFX(AppRsp)(%rip), %rax
312 // UINT64 Cr0, Cr1, Cr2, Cr3, Cr4, Cr8;
313 // insure FXSAVE/FXRSTOR is enabled in CR4...
314 // ... while we're at it, make sure DE is also enabled...
328 // UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
331 // clear Dr7 while executing debugger itself
337 // insure all status bits in dr6 are clear...
350 // FX_SAVE_STATE_X64 FxSaveState;
353 # IMPORTANT!! The debug stack has been carefully constructed to
354 # insure that rsp and rdi are 16 byte aligned when we get here.
355 # They MUST be. If they are not, a GP fault will occur.
360 // UEFI calling convention for x64 requires that Direction flag in EFLAGs is clear
363 // UINT64 ExceptionData;
364 movq ASM_PFX(ExceptData)(%rip), %rax
367 // call to C code which will in turn call registered handler
368 // pass in the vector number
370 movq ASM_PFX(ExceptionNumber)(%rip), %rcx
372 call ASM_PFX(InterruptDistrubutionHub)
374 // restore context...
375 // UINT64 ExceptionData;
378 // FX_SAVE_STATE_X64 FxSaveState;
386 // UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
396 // skip restore of dr6. We cleared dr6 during the context save.
401 // UINT64 Cr0, Cr1, Cr2, Cr3, Cr4, Cr8;
414 movq ASM_PFX(AppRsp)(%rip), %rax
417 // UINT64 Gdtr[2], Idtr[2];
418 // Best not let anyone mess with these particular registers...
423 // UINT64 Gs, Fs, Es, Ds, Cs, Ss;
424 // NOTE - modified segment registers could hang the debugger... We
425 // could attempt to insulate ourselves against this possibility,
426 // but that poses risks as well.
437 movq ASM_PFX(AppRsp)(%rip), %rax
441 ## The next stuff to restore is the general purpose registers that were pushed
442 ## using the "push" instruction.
444 ## The value of RSP as stored in the context record is the application RSP
445 ## including the 5 entries on the application stack caused by the exception
446 ## itself. It may have been modified by the debug agent, so we need to
447 ## determine if we need to relocate the application stack.
449 movq 24(%rsp), %rbx # move the potentially modified AppRsp into rbx
450 movq ASM_PFX(AppRsp)(%rip), %rax
455 movq ASM_PFX(AppRsp)(%rip), %rax
456 movq (%rax), %rcx # RIP
459 movq 8(%rax), %rcx # CS
462 movq 16(%rax), %rcx # RFLAGS
465 movq 24(%rax), %rcx # RSP
468 movq 32(%rax), %rcx # SS
471 movq %rbx, %rax # modify the saved AppRsp to the new AppRsp
472 movq %rax, ASM_PFX(AppRsp)(%rip)
474 movq ASM_PFX(DebugRsp)(%rip), %rax # restore the DebugRsp on the debug stack
475 # so our "pop" will not cause a stack switch
478 cmpl $0x068, ASM_PFX(ExceptionNumber)(%rip)
483 // Restore rflags so when we chain, the flags will be exactly as if we were never here.
484 // We gin up the stack to do an iretq so we can get ALL the flags.
485 movq ASM_PFX(AppRsp)(%rip), %rax
493 movq ASM_PFX(AppRsp)(%rip), %rax
495 andq $0xfffffffffffffcff, %rbx # special handling for IF and TF
499 movq PhonyIretq(%rip), %rax
504 // UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
505 // UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
523 // Switch back to application stack
524 movq ASM_PFX(AppRsp)(%rip), %rsp
525 // Jump to original handler
526 jmp ASM_PFX(OrigVector)
528 // UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
529 // UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
547 // Switch back to application stack
548 movq ASM_PFX(AppRsp)(%rip), %rsp
550 // We're outa here...