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UefiCpuPkg: BaseRiscV64CpuExceptionHandlerLib: clean up
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RegisterCpuInterruptHandler did not allow setting
exception handlers for anything beyond the timer IRQ.
Beyond that, it didn't meet the spec around handling
of inputs.

RiscVSupervisorModeTrapHandler now will invoke
set handlers for both exceptions and interrupts.
Two arrays of handlers are maintained - one for exceptions
and one for interrupts.

For unhandled traps, RiscVSupervisorModeTrapHandler dumps
state using the now implemented DumpCpuContext.

For EFI_SYSTEM_CONTEXT_RISCV64, extend this with the trapped
PC address (SEPC), just like on AArch64 (ELR). This is
necessary for X86EmulatorPkg to work as it allows a trap
handler to return execution to a different place. Add
SSTATUS/STVAL as well, at least for debugging purposes. There
is no value in hiding this.

Fix nested exception handling. Handler code should not
be saving SIE (the value is saved in SSTATUS.SPIE) or
directly restored (that's done by SRET). Save and
restore the entire SSTATUS and STVAL, too.

Cc: Daniel Schaefer <[email protected]>
Reviewed-by: Sunil V L <[email protected]>
Signed-off-by: Andrei Warkentin <[email protected]>
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Andrei Warkentin authored and mergify[bot] committed Mar 8, 2023
1 parent 5ad2592 commit 69da506
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Showing 5 changed files with 261 additions and 45 deletions.
34 changes: 30 additions & 4 deletions MdePkg/Include/Protocol/DebugSupport.h
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Original file line number Diff line number Diff line change
Expand Up @@ -613,11 +613,34 @@ typedef struct {
#define EXCEPT_RISCV_STORE_AMO_ACCESS_FAULT 7
#define EXCEPT_RISCV_ENV_CALL_FROM_UMODE 8
#define EXCEPT_RISCV_ENV_CALL_FROM_SMODE 9
#define EXCEPT_RISCV_ENV_CALL_FROM_HMODE 10
#define EXCEPT_RISCV_ENV_CALL_FROM_VS_MODE 10
#define EXCEPT_RISCV_ENV_CALL_FROM_MMODE 11

#define EXCEPT_RISCV_SOFTWARE_INT 0x0
#define EXCEPT_RISCV_TIMER_INT 0x1
#define EXCEPT_RISCV_INST_ACCESS_PAGE_FAULT 12
#define EXCEPT_RISCV_LOAD_ACCESS_PAGE_FAULT 13
#define EXCEPT_RISCV_14 14
#define EXCEPT_RISCV_STORE_ACCESS_PAGE_FAULT 15
#define EXCEPT_RISCV_16 16
#define EXCEPT_RISCV_17 17
#define EXCEPT_RISCV_18 18
#define EXCEPT_RISCV_19 19
#define EXCEPT_RISCV_INST_GUEST_PAGE_FAULT 20
#define EXCEPT_RISCV_LOAD_GUEST_PAGE_FAULT 21
#define EXCEPT_RISCV_VIRTUAL_INSTRUCTION 22
#define EXCEPT_RISCV_STORE_GUEST_PAGE_FAULT 23
#define EXCEPT_RISCV_MAX_EXCEPTIONS (EXCEPT_RISCV_STORE_GUEST_PAGE_FAULT)

///
/// RISC-V processor exception types for interrupts.
///
#define EXCEPT_RISCV_IS_IRQ(x) ((x & 0x8000000000000000UL) != 0)
#define EXCEPT_RISCV_IRQ_INDEX(x) (x & 0x7FFFFFFFFFFFFFFFUL)
#define EXCEPT_RISCV_IRQ_0 0x8000000000000000UL
#define EXCEPT_RISCV_IRQ_SOFT_FROM_SMODE 0x8000000000000001UL
#define EXCEPT_RISCV_IRQ_SOFT_FROM_VSMODE 0x8000000000000002UL
#define EXCEPT_RISCV_IRQ_SOFT_FROM_MMODE 0x8000000000000003UL
#define EXCEPT_RISCV_IRQ_4 0x8000000000000004UL
#define EXCEPT_RISCV_IRQ_TIMER_FROM_SMODE 0x8000000000000005UL
#define EXCEPT_RISCV_MAX_IRQS (EXCEPT_RISCV_IRQ_INDEX(EXCEPT_RISCV_IRQ_TIMER_FROM_SMODE))

typedef struct {
UINT64 X0;
Expand Down Expand Up @@ -652,6 +675,9 @@ typedef struct {
UINT64 X29;
UINT64 X30;
UINT64 X31;
UINT64 SEPC;
UINT32 SSTATUS;
UINT32 STVAL;
} EFI_SYSTEM_CONTEXT_RISCV64;

//
Expand Down
6 changes: 5 additions & 1 deletion UefiCpuPkg/CpuTimerDxeRiscV64/Timer.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -278,7 +278,11 @@ TimerDriverInitialize (
//
// Install interrupt handler for RISC-V Timer.
//
Status = mCpu->RegisterInterruptHandler (mCpu, EXCEPT_RISCV_TIMER_INT, TimerInterruptHandler);
Status = mCpu->RegisterInterruptHandler (
mCpu,
EXCEPT_RISCV_IRQ_TIMER_FROM_SMODE,
TimerInterruptHandler
);
ASSERT_EFI_ERROR (Status);

//
Expand Down
238 changes: 215 additions & 23 deletions UefiCpuPkg/Library/BaseRiscV64CpuExceptionHandlerLib/CpuExceptionHandlerLib.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,11 +11,168 @@
#include <Library/CpuExceptionHandlerLib.h>
#include <Library/DebugLib.h>
#include <Library/BaseLib.h>
#include <Library/SerialPortLib.h>
#include <Library/PrintLib.h>
#include <Register/RiscV64/RiscVEncoding.h>

#include "CpuExceptionHandlerLib.h"

STATIC EFI_CPU_INTERRUPT_HANDLER mInterruptHandlers[2];
//
// Define the maximum message length
//
#define MAX_DEBUG_MESSAGE_LENGTH 0x100

STATIC EFI_CPU_INTERRUPT_HANDLER mExceptionHandlers[EXCEPT_RISCV_MAX_EXCEPTIONS + 1];
STATIC EFI_CPU_INTERRUPT_HANDLER mIrqHandlers[EXCEPT_RISCV_MAX_IRQS + 1];

STATIC CONST CHAR8 mExceptionOrIrqUnknown[] = "Unknown";
STATIC CONST CHAR8 *mExceptionNameStr[EXCEPT_RISCV_MAX_EXCEPTIONS + 1] = {
"EXCEPT_RISCV_INST_MISALIGNED",
"EXCEPT_RISCV_INST_ACCESS_FAULT",
"EXCEPT_RISCV_ILLEGAL_INST",
"EXCEPT_RISCV_BREAKPOINT",
"EXCEPT_RISCV_LOAD_ADDRESS_MISALIGNED",
"EXCEPT_RISCV_LOAD_ACCESS_FAULT",
"EXCEPT_RISCV_STORE_AMO_ADDRESS_MISALIGNED",
"EXCEPT_RISCV_STORE_AMO_ACCESS_FAULT",
"EXCEPT_RISCV_ENV_CALL_FROM_UMODE",
"EXCEPT_RISCV_ENV_CALL_FROM_SMODE",
"EXCEPT_RISCV_ENV_CALL_FROM_VS_MODE",
"EXCEPT_RISCV_ENV_CALL_FROM_MMODE",
"EXCEPT_RISCV_INST_ACCESS_PAGE_FAULT",
"EXCEPT_RISCV_LOAD_ACCESS_PAGE_FAULT",
"EXCEPT_RISCV_14",
"EXCEPT_RISCV_STORE_ACCESS_PAGE_FAULT",
"EXCEPT_RISCV_16",
"EXCEPT_RISCV_17",
"EXCEPT_RISCV_18",
"EXCEPT_RISCV_19",
"EXCEPT_RISCV_INST_GUEST_PAGE_FAULT",
"EXCEPT_RISCV_LOAD_GUEST_PAGE_FAULT",
"EXCEPT_RISCV_VIRTUAL_INSTRUCTION",
"EXCEPT_RISCV_STORE_GUEST_PAGE_FAULT"
};

STATIC CONST CHAR8 *mIrqNameStr[EXCEPT_RISCV_MAX_IRQS + 1] = {
"EXCEPT_RISCV_IRQ_0",
"EXCEPT_RISCV_IRQ_SOFT_FROM_SMODE",
"EXCEPT_RISCV_IRQ_SOFT_FROM_VSMODE",
"EXCEPT_RISCV_IRQ_SOFT_FROM_MMODE",
"EXCEPT_RISCV_IRQ_4",
"EXCEPT_RISCV_IRQ_TIMER_FROM_SMODE",
};

/**
Prints a message to the serial port.
@param Format Format string for the message to print.
@param ... Variable argument list whose contents are accessed
based on the format string specified by Format.
**/
STATIC
VOID
EFIAPI
InternalPrintMessage (
IN CONST CHAR8 *Format,
...
)
{
CHAR8 Buffer[MAX_DEBUG_MESSAGE_LENGTH];
VA_LIST Marker;

//
// Convert the message to an ASCII String
//
VA_START (Marker, Format);
AsciiVSPrint (Buffer, sizeof (Buffer), Format, Marker);
VA_END (Marker);

//
// Send the print string to a Serial Port
//
SerialPortWrite ((UINT8 *)Buffer, AsciiStrLen (Buffer));
}

/**
Get ASCII format string exception name by exception type.
@param ExceptionType Exception type.
@return ASCII format string exception name.
**/
STATIC
CONST CHAR8 *
GetExceptionNameStr (
IN EFI_EXCEPTION_TYPE ExceptionType
)
{
if (EXCEPT_RISCV_IS_IRQ (ExceptionType)) {
if (EXCEPT_RISCV_IRQ_INDEX (ExceptionType) > EXCEPT_RISCV_MAX_IRQS) {
return mExceptionOrIrqUnknown;
}

return mIrqNameStr[EXCEPT_RISCV_IRQ_INDEX (ExceptionType)];
}

if (ExceptionType > EXCEPT_RISCV_MAX_EXCEPTIONS) {
return mExceptionOrIrqUnknown;
}

return mExceptionNameStr[ExceptionType];
}

/**
Display CPU information. This can be called by 3rd-party handlers
set by RegisterCpuInterruptHandler.
@param ExceptionType Exception type.
@param SystemContext Pointer to EFI_SYSTEM_CONTEXT.
**/
VOID
EFIAPI
DumpCpuContext (
IN EFI_EXCEPTION_TYPE ExceptionType,
IN EFI_SYSTEM_CONTEXT SystemContext
)
{
UINTN Printed;
SMODE_TRAP_REGISTERS *Regs;

Printed = 0;
Regs = (SMODE_TRAP_REGISTERS *)SystemContext.SystemContextRiscV64;

InternalPrintMessage (
"!!!! RISCV64 Exception Type - %016x(%a) !!!!\n",
ExceptionType,
GetExceptionNameStr (ExceptionType)
);

DEBUG_CODE_BEGIN ();

#define REGS() \
REG (t0); REG (t1); REG (t2); REG (t3); REG (t4); REG (t5); REG (t6); \
REG (s0); REG (s1); REG (s2); REG (s3); REG (s4); REG (s5); REG (s6); \
REG (s7); REG (s8); REG (s9); REG (s10); REG (s11); \
REG (a0); REG (a1); REG (a2); REG (a3); REG (a4); REG (a5); REG (a6); \
REG (a7); \
REG (zero); REG (ra); REG (sp); REG (gp); REG (tp); \
REG (sepc); REG (sstatus); REG (stval);

#define REG(x) do { \
InternalPrintMessage ("%7a = 0x%017lx%c", #x, Regs->x, \
(++Printed % 2) ? L'\t' : L'\n'); \
} while (0);

REGS ();
if (Printed % 2 != 0) {
InternalPrintMessage ("\n");
}

#undef REG
#undef REGS

DEBUG_CODE_END ();
}

/**
Initializes all CPU exceptions entries and provides the default exception handlers.
Expand Down Expand Up @@ -47,34 +204,59 @@ InitializeCpuExceptionHandlers (
Registers a function to be called from the processor interrupt handler.
This function registers and enables the handler specified by InterruptHandler for a processor
interrupt or exception type specified by InterruptType. If InterruptHandler is NULL, then the
handler for the processor interrupt or exception type specified by InterruptType is uninstalled.
interrupt or exception type specified by ExceptionType. If InterruptHandler is NULL, then the
handler for the processor interrupt or exception type specified by ExceptionType is uninstalled.
The installed handler is called once for each processor interrupt or exception.
NOTE: This function should be invoked after InitializeCpuExceptionHandlers() or
InitializeCpuInterruptHandlers() invoked, otherwise EFI_UNSUPPORTED returned.
@param[in] InterruptType Defines which interrupt or exception to hook.
@param[in] ExceptionType Defines which interrupt or exception to hook.
@param[in] InterruptHandler A pointer to a function of type EFI_CPU_INTERRUPT_HANDLER that is called
when a processor interrupt occurs. If this parameter is NULL, then the handler
will be uninstalled.
@retval EFI_SUCCESS The handler for the processor interrupt was successfully installed or uninstalled.
@retval EFI_ALREADY_STARTED InterruptHandler is not NULL, and a handler for InterruptType was
@retval EFI_ALREADY_STARTED InterruptHandler is not NULL, and a handler for ExceptionType was
previously installed.
@retval EFI_INVALID_PARAMETER InterruptHandler is NULL, and a handler for InterruptType was not
@retval EFI_INVALID_PARAMETER InterruptHandler is NULL, and a handler for ExceptionType was not
previously installed.
@retval EFI_UNSUPPORTED The interrupt specified by InterruptType is not supported,
@retval EFI_UNSUPPORTED The interrupt specified by ExceptionType is not supported,
or this function is not supported.
**/
EFI_STATUS
EFIAPI
RegisterCpuInterruptHandler (
IN EFI_EXCEPTION_TYPE InterruptType,
IN EFI_EXCEPTION_TYPE ExceptionType,
IN EFI_CPU_INTERRUPT_HANDLER InterruptHandler
)
{
DEBUG ((DEBUG_INFO, "%a: Type:%x Handler: %x\n", __FUNCTION__, InterruptType, InterruptHandler));
mInterruptHandlers[InterruptType] = InterruptHandler;
DEBUG ((DEBUG_INFO, "%a: Type:%x Handler: %x\n", __FUNCTION__, ExceptionType, InterruptHandler));
if (EXCEPT_RISCV_IS_IRQ (ExceptionType)) {
if (EXCEPT_RISCV_IRQ_INDEX (ExceptionType) > EXCEPT_RISCV_MAX_IRQS) {
return EFI_UNSUPPORTED;
}

if (mIrqHandlers[EXCEPT_RISCV_IRQ_INDEX (ExceptionType)] != NULL) {
return EFI_ALREADY_STARTED;
} else if (InterruptHandler == NULL) {
return EFI_INVALID_PARAMETER;
}

mIrqHandlers[EXCEPT_RISCV_IRQ_INDEX (ExceptionType)] = InterruptHandler;
} else {
if (ExceptionType > EXCEPT_RISCV_MAX_EXCEPTIONS) {
return EFI_UNSUPPORTED;
}

if (mExceptionHandlers[ExceptionType] != NULL) {
return EFI_ALREADY_STARTED;
} else if (InterruptHandler == NULL) {
return EFI_INVALID_PARAMETER;
}

mExceptionHandlers[ExceptionType] = InterruptHandler;
}

return EFI_SUCCESS;
}

Expand Down Expand Up @@ -113,21 +295,31 @@ RiscVSupervisorModeTrapHandler (
SMODE_TRAP_REGISTERS *SmodeTrapReg
)
{
UINTN SCause;
EFI_EXCEPTION_TYPE ExceptionType;
EFI_SYSTEM_CONTEXT RiscVSystemContext;
UINTN IrqIndex;

RiscVSystemContext.SystemContextRiscV64 = (EFI_SYSTEM_CONTEXT_RISCV64 *)SmodeTrapReg;
//
// Check scasue register.
//
SCause = (UINTN)RiscVGetSupervisorTrapCause ();
if ((SCause & (1UL << (sizeof (UINTN) * 8- 1))) != 0) {
//
// This is interrupt event.
//
SCause &= ~(1UL << (sizeof (UINTN) * 8- 1));
if ((SCause == IRQ_S_TIMER) && (mInterruptHandlers[EXCEPT_RISCV_TIMER_INT] != NULL)) {
mInterruptHandlers[EXCEPT_RISCV_TIMER_INT](EXCEPT_RISCV_TIMER_INT, RiscVSystemContext);
ExceptionType = (UINTN)RiscVGetSupervisorTrapCause ();

if (EXCEPT_RISCV_IS_IRQ (ExceptionType)) {
IrqIndex = EXCEPT_RISCV_IRQ_INDEX (ExceptionType);

if ((IrqIndex <= EXCEPT_RISCV_MAX_IRQS) &&
(mIrqHandlers[IrqIndex] != NULL))
{
mIrqHandlers[IrqIndex](ExceptionType, RiscVSystemContext);
return;
}
} else {
if ((ExceptionType <= EXCEPT_RISCV_MAX_EXCEPTIONS) &&
(mExceptionHandlers[ExceptionType] != 0))
{
mExceptionHandlers[ExceptionType](ExceptionType, RiscVSystemContext);
return;
}
}

DumpCpuContext (ExceptionType, RiscVSystemContext);
CpuDeadLoop ();
}
11 changes: 3 additions & 8 deletions UefiCpuPkg/Library/BaseRiscV64CpuExceptionHandlerLib/CpuExceptionHandlerLib.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,7 +59,7 @@ SupervisorModeTrap (
#define SMODE_TRAP_REGS_t6 31
#define SMODE_TRAP_REGS_sepc 32
#define SMODE_TRAP_REGS_sstatus 33
#define SMODE_TRAP_REGS_sie 34
#define SMODE_TRAP_REGS_stval 34
#define SMODE_TRAP_REGS_last 35

#define SMODE_TRAP_REGS_OFFSET(x) ((SMODE_TRAP_REGS_##x) * __SIZEOF_POINTER__)
Expand All @@ -68,7 +68,7 @@ SupervisorModeTrap (
#pragma pack(1)
typedef struct {
//
// Below are follow the format of EFI_SYSTEM_CONTEXT
// Below follow the format of EFI_SYSTEM_CONTEXT.
//
UINT64 zero;
UINT64 ra;
Expand Down Expand Up @@ -102,14 +102,9 @@ typedef struct {
UINT64 t4;
UINT64 t5;
UINT64 t6;
//
// Below are the additional information to
// EFI_SYSTEM_CONTEXT, private to supervisor mode trap
// and not public to EFI environment.
//
UINT64 sepc;
UINT64 sstatus;
UINT64 sie;
UINT64 stval;
} SMODE_TRAP_REGISTERS;
#pragma pack()

Expand Down
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