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https://github.com/ipxe/ipxe
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89e31f8491
When DEBUG=librm_mgmt is enabled, intercept CPU exceptions and provide a register and stack dump, then drop to an emergency shell. Exiting from the shell will almost certainly not work, but this provides an opportunity to view the register and stack dump and carry out some basic debugging. Note that we can intercept only the first 8 CPU exceptions, since a PXE ROM is not permitted to rebase the PIC. Signed-off-by: Michael Brown <mcb30@ipxe.org>
402 lines
12 KiB
C
402 lines
12 KiB
C
/*
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* librm: a library for interfacing to real-mode code
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*
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* Michael Brown <mbrown@fensystems.co.uk>
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*
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <stdint.h>
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#include <strings.h>
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#include <assert.h>
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#include <ipxe/profile.h>
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#include <realmode.h>
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#include <pic8259.h>
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#include <ipxe/shell.h>
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/*
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* This file provides functions for managing librm.
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*
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*/
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/** The interrupt wrapper */
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extern char interrupt_wrapper[];
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/** The interrupt vectors */
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static struct interrupt_vector intr_vec[NUM_INT];
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/** The 32-bit interrupt descriptor table */
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static struct interrupt32_descriptor
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idt32[NUM_INT] __attribute__ (( aligned ( 16 ) ));
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/** The 32-bit interrupt descriptor table register */
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struct idtr32 idtr32 = {
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.limit = ( sizeof ( idt32 ) - 1 ),
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};
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/** The 64-bit interrupt descriptor table */
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static struct interrupt64_descriptor
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idt64[NUM_INT] __attribute__ (( aligned ( 16 ) ));
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/** The interrupt descriptor table register */
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struct idtr64 idtr64 = {
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.limit = ( sizeof ( idt64 ) - 1 ),
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};
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/** Length of stack dump */
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#define STACK_DUMP_LEN 128
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/** Timer interrupt profiler */
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static struct profiler timer_irq_profiler __profiler = { .name = "irq.timer" };
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/** Other interrupt profiler */
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static struct profiler other_irq_profiler __profiler = { .name = "irq.other" };
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/**
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* Allocate space on the real-mode stack and copy data there from a
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* user buffer
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*
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* @v data User buffer
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* @v size Size of stack data
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* @ret sp New value of real-mode stack pointer
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*/
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uint16_t copy_user_to_rm_stack ( userptr_t data, size_t size ) {
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userptr_t rm_stack;
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rm_sp -= size;
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rm_stack = real_to_user ( rm_ss, rm_sp );
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memcpy_user ( rm_stack, 0, data, 0, size );
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return rm_sp;
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};
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/**
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* Deallocate space on the real-mode stack, optionally copying back
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* data to a user buffer.
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*
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* @v data User buffer
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* @v size Size of stack data
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*/
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void remove_user_from_rm_stack ( userptr_t data, size_t size ) {
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if ( data ) {
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userptr_t rm_stack = real_to_user ( rm_ss, rm_sp );
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memcpy_user ( rm_stack, 0, data, 0, size );
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}
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rm_sp += size;
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};
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/**
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* Set interrupt vector
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*
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* @v intr Interrupt number
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* @v vector Interrupt vector, or NULL to disable
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*/
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void set_interrupt_vector ( unsigned int intr, void *vector ) {
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struct interrupt32_descriptor *idte32;
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struct interrupt64_descriptor *idte64;
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intptr_t addr = ( ( intptr_t ) vector );
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/* Populate 32-bit interrupt descriptor */
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idte32 = &idt32[intr];
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idte32->segment = VIRTUAL_CS;
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idte32->attr = ( vector ? ( IDTE_PRESENT | IDTE_TYPE_IRQ32 ) : 0 );
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idte32->low = ( addr >> 0 );
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idte32->high = ( addr >> 16 );
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/* Populate 64-bit interrupt descriptor, if applicable */
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if ( sizeof ( physaddr_t ) > sizeof ( uint32_t ) ) {
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idte64 = &idt64[intr];
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idte64->segment = LONG_CS;
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idte64->attr = ( vector ?
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( IDTE_PRESENT | IDTE_TYPE_IRQ64 ) : 0 );
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idte64->low = ( addr >> 0 );
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idte64->mid = ( addr >> 16 );
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idte64->high = ( ( ( uint64_t ) addr ) >> 32 );
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}
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}
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/**
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* Initialise interrupt descriptor table
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*
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*/
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void init_idt ( void ) {
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struct interrupt_vector *vec;
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unsigned int intr;
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/* Initialise the interrupt descriptor table and interrupt vectors */
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for ( intr = 0 ; intr < NUM_INT ; intr++ ) {
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vec = &intr_vec[intr];
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vec->push = PUSH_INSN;
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vec->movb = MOVB_INSN;
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vec->intr = intr;
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vec->jmp = JMP_INSN;
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vec->offset = ( ( intptr_t ) interrupt_wrapper -
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( intptr_t ) vec->next );
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set_interrupt_vector ( intr, vec );
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}
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DBGC ( &intr_vec[0], "INTn vector at %p+%zxn (phys %#lx+%zxn)\n",
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intr_vec, sizeof ( intr_vec[0] ),
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virt_to_phys ( intr_vec ), sizeof ( intr_vec[0] ) );
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/* Initialise the 32-bit interrupt descriptor table register */
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idtr32.base = virt_to_phys ( idt32 );
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/* Initialise the 64-bit interrupt descriptor table register,
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* if applicable.
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*/
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if ( sizeof ( physaddr_t ) > sizeof ( uint32_t ) )
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idtr64.base = virt_to_phys ( idt64 );
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}
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/**
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* Determine interrupt profiler (for debugging)
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*
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* @v intr Interrupt number
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* @ret profiler Profiler
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*/
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static struct profiler * interrupt_profiler ( int intr ) {
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switch ( intr ) {
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case IRQ_INT ( 0 ) :
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return &timer_irq_profiler;
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default:
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return &other_irq_profiler;
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}
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}
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/**
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* Display interrupt stack dump (for debugging)
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*
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* @v intr Interrupt number
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* @v frame32 32-bit interrupt wrapper stack frame (or NULL)
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* @v frame64 64-bit interrupt wrapper stack frame (or NULL)
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*/
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static __attribute__ (( unused )) void
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interrupt_dump ( int intr, struct interrupt_frame32 *frame32,
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struct interrupt_frame64 *frame64 ) {
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unsigned long sp;
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void *stack;
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/* Do nothing unless debugging is enabled */
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if ( ! DBG_LOG )
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return;
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/* Print register dump */
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if ( ( sizeof ( physaddr_t ) <= sizeof ( uint32_t ) ) || frame32 ) {
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sp = ( frame32->esp + sizeof ( *frame32 ) -
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offsetof ( typeof ( *frame32 ), esp ) );
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DBGC ( &intr, "INT%d at %04x:%08x (stack %04x:%08lx):\n",
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intr, frame32->cs, frame32->eip, frame32->ss, sp );
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DBGC ( &intr, "cs = %04x ds = %04x es = %04x fs = %04x "
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"gs = %04x ss = %04x\n", frame32->cs, frame32->ds,
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frame32->es, frame32->fs, frame32->gs, frame32->ss );
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DBGC ( &intr, "eax = %08x ebx = %08x ecx = %08x "
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"edx = %08x flg = %08x\n", frame32->eax, frame32->ebx,
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frame32->ecx, frame32->edx, frame32->eflags );
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DBGC ( &intr, "esi = %08x edi = %08x ebp = %08x "
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"esp = %08lx eip = %08x\n", frame32->esi, frame32->edi,
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frame32->ebp, sp, frame32->eip );
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stack = ( ( ( void * ) frame32 ) + sizeof ( *frame32 ) );
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} else {
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DBGC ( &intr, "INT%d at %04llx:%016llx (stack "
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"%04llx:%016llx):\n", intr,
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( ( unsigned long long ) frame64->cs ),
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( ( unsigned long long ) frame64->rip ),
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( ( unsigned long long ) frame64->ss ),
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( ( unsigned long long ) frame64->rsp ) );
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DBGC ( &intr, "rax = %016llx rbx = %016llx rcx = %016llx\n",
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( ( unsigned long long ) frame64->rax ),
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( ( unsigned long long ) frame64->rbx ),
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( ( unsigned long long ) frame64->rcx ) );
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DBGC ( &intr, "rdx = %016llx rsi = %016llx rdi = %016llx\n",
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( ( unsigned long long ) frame64->rdx ),
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( ( unsigned long long ) frame64->rsi ),
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( ( unsigned long long ) frame64->rdi ) );
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DBGC ( &intr, "rbp = %016llx rsp = %016llx flg = %016llx\n",
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( ( unsigned long long ) frame64->rbp ),
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( ( unsigned long long ) frame64->rsp ),
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( ( unsigned long long ) frame64->rflags ) );
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DBGC ( &intr, "r8 = %016llx r9 = %016llx r10 = %016llx\n",
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( ( unsigned long long ) frame64->r8 ),
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( ( unsigned long long ) frame64->r9 ),
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( ( unsigned long long ) frame64->r10 ) );
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DBGC ( &intr, "r11 = %016llx r12 = %016llx r13 = %016llx\n",
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( ( unsigned long long ) frame64->r11 ),
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( ( unsigned long long ) frame64->r12 ),
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( ( unsigned long long ) frame64->r13 ) );
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DBGC ( &intr, "r14 = %016llx r15 = %016llx\n",
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( ( unsigned long long ) frame64->r14 ),
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( ( unsigned long long ) frame64->r15 ) );
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sp = frame64->rsp;
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stack = phys_to_virt ( sp );
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}
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/* Print stack dump */
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DBGC_HDA ( &intr, sp, stack, STACK_DUMP_LEN );
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}
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/**
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* Interrupt handler
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*
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* @v intr Interrupt number
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* @v frame32 32-bit interrupt wrapper stack frame (or NULL)
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* @v frame64 64-bit interrupt wrapper stack frame (or NULL)
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* @v frame Interrupt wrapper stack frame
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*/
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void __attribute__ (( regparm ( 3 ) ))
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interrupt ( int intr, struct interrupt_frame32 *frame32,
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struct interrupt_frame64 *frame64 ) {
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struct profiler *profiler = interrupt_profiler ( intr );
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uint32_t discard_eax;
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/* Trap CPU exceptions if debugging is enabled. Note that we
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* cannot treat INT8+ as exceptions, since we are not
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* permitted to rebase the PIC.
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*/
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if ( DBG_LOG && ( intr < IRQ_INT ( 0 ) ) ) {
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interrupt_dump ( intr, frame32, frame64 );
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DBG ( "CPU exception: dropping to emergency shell\n" );
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shell();
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}
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/* Reissue interrupt in real mode */
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profile_start ( profiler );
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__asm__ __volatile__ ( REAL_CODE ( "movb %%al, %%cs:(1f + 1)\n\t"
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"\n1:\n\t"
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"int $0x00\n\t" )
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: "=a" ( discard_eax ) : "0" ( intr ) );
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profile_stop ( profiler );
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profile_exclude ( profiler );
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}
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/**
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* Map pages for I/O
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*
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* @v bus_addr Bus address
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* @v len Length of region
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* @ret io_addr I/O address
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*/
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static void * ioremap_pages ( unsigned long bus_addr, size_t len ) {
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unsigned long start;
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unsigned int count;
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unsigned int stride;
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unsigned int first;
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unsigned int i;
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size_t offset;
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void *io_addr;
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DBGC ( &io_pages, "IO mapping %08lx+%zx\n", bus_addr, len );
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/* Sanity check */
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if ( ! len )
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return NULL;
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/* Round down start address to a page boundary */
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start = ( bus_addr & ~( IO_PAGE_SIZE - 1 ) );
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offset = ( bus_addr - start );
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assert ( offset < IO_PAGE_SIZE );
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/* Calculate number of pages required */
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count = ( ( offset + len + IO_PAGE_SIZE - 1 ) / IO_PAGE_SIZE );
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assert ( count != 0 );
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assert ( count < ( sizeof ( io_pages.page ) /
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sizeof ( io_pages.page[0] ) ) );
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/* Round up number of pages to a power of two */
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stride = ( 1 << ( fls ( count ) - 1 ) );
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assert ( count <= stride );
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/* Allocate pages */
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for ( first = 0 ; first < ( sizeof ( io_pages.page ) /
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sizeof ( io_pages.page[0] ) ) ;
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first += stride ) {
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/* Calculate I/O address */
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io_addr = ( IO_BASE + ( first * IO_PAGE_SIZE ) + offset );
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/* Check that page table entries are available */
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for ( i = first ; i < ( first + count ) ; i++ ) {
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if ( io_pages.page[i] & PAGE_P ) {
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io_addr = NULL;
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break;
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}
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}
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if ( ! io_addr )
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continue;
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/* Create page table entries */
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for ( i = first ; i < ( first + count ) ; i++ ) {
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io_pages.page[i] = ( start | PAGE_P | PAGE_RW |
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PAGE_US | PAGE_PWT | PAGE_PCD |
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PAGE_PS );
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start += IO_PAGE_SIZE;
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}
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/* Mark last page as being the last in this allocation */
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io_pages.page[ i - 1 ] |= PAGE_LAST;
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/* Return I/O address */
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DBGC ( &io_pages, "IO mapped %08lx+%zx to %p using PTEs "
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"[%d-%d]\n", bus_addr, len, io_addr, first,
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( first + count - 1 ) );
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return io_addr;
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}
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DBGC ( &io_pages, "IO could not map %08lx+%zx\n", bus_addr, len );
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return NULL;
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}
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/**
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* Unmap pages for I/O
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*
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* @v io_addr I/O address
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*/
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static void iounmap_pages ( volatile const void *io_addr ) {
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volatile const void *invalidate = io_addr;
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unsigned int first;
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unsigned int i;
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int is_last;
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DBGC ( &io_pages, "IO unmapping %p\n", io_addr );
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/* Calculate first page table entry */
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first = ( ( io_addr - IO_BASE ) / IO_PAGE_SIZE );
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/* Clear page table entries */
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for ( i = first ; ; i++ ) {
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/* Sanity check */
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assert ( io_pages.page[i] & PAGE_P );
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/* Check if this is the last page in this allocation */
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is_last = ( io_pages.page[i] & PAGE_LAST );
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/* Clear page table entry */
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io_pages.page[i] = 0;
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/* Invalidate TLB for this page */
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__asm__ __volatile__ ( "invlpg (%0)" : : "r" ( invalidate ) );
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invalidate += IO_PAGE_SIZE;
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/* Terminate if this was the last page */
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if ( is_last )
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break;
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}
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DBGC ( &io_pages, "IO unmapped %p using PTEs [%d-%d]\n",
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io_addr, first, i );
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}
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PROVIDE_UACCESS_INLINE ( librm, phys_to_user );
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PROVIDE_UACCESS_INLINE ( librm, user_to_phys );
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PROVIDE_UACCESS_INLINE ( librm, virt_to_user );
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PROVIDE_UACCESS_INLINE ( librm, user_to_virt );
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PROVIDE_UACCESS_INLINE ( librm, userptr_add );
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PROVIDE_UACCESS_INLINE ( librm, memcpy_user );
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PROVIDE_UACCESS_INLINE ( librm, memmove_user );
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PROVIDE_UACCESS_INLINE ( librm, memset_user );
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PROVIDE_UACCESS_INLINE ( librm, strlen_user );
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PROVIDE_UACCESS_INLINE ( librm, memchr_user );
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PROVIDE_IOMAP_INLINE ( pages, io_to_bus );
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PROVIDE_IOMAP ( pages, ioremap, ioremap_pages );
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PROVIDE_IOMAP ( pages, iounmap, iounmap_pages );
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