lguest: fix comment style
I don't really notice it (except to begrudge the extra vertical
space), but Ingo does. And he pointed out that one excuse of lguest
is as a teaching tool, it should set a good example.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index eaf722f..96f7d88 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -17,13 +17,15 @@
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
-/*P:450 This file contains the x86-specific lguest code. It used to be all
+/*P:450
+ * This file contains the x86-specific lguest code. It used to be all
* mixed in with drivers/lguest/core.c but several foolhardy code slashers
* wrestled most of the dependencies out to here in preparation for porting
* lguest to other architectures (see what I mean by foolhardy?).
*
* This also contains a couple of non-obvious setup and teardown pieces which
- * were implemented after days of debugging pain. :*/
+ * were implemented after days of debugging pain.
+:*/
#include <linux/kernel.h>
#include <linux/start_kernel.h>
#include <linux/string.h>
@@ -82,25 +84,33 @@
*/
static void copy_in_guest_info(struct lg_cpu *cpu, struct lguest_pages *pages)
{
- /* Copying all this data can be quite expensive. We usually run the
+ /*
+ * Copying all this data can be quite expensive. We usually run the
* same Guest we ran last time (and that Guest hasn't run anywhere else
* meanwhile). If that's not the case, we pretend everything in the
- * Guest has changed. */
+ * Guest has changed.
+ */
if (__get_cpu_var(last_cpu) != cpu || cpu->last_pages != pages) {
__get_cpu_var(last_cpu) = cpu;
cpu->last_pages = pages;
cpu->changed = CHANGED_ALL;
}
- /* These copies are pretty cheap, so we do them unconditionally: */
- /* Save the current Host top-level page directory. */
+ /*
+ * These copies are pretty cheap, so we do them unconditionally: */
+ /* Save the current Host top-level page directory.
+ */
pages->state.host_cr3 = __pa(current->mm->pgd);
- /* Set up the Guest's page tables to see this CPU's pages (and no
- * other CPU's pages). */
+ /*
+ * Set up the Guest's page tables to see this CPU's pages (and no
+ * other CPU's pages).
+ */
map_switcher_in_guest(cpu, pages);
- /* Set up the two "TSS" members which tell the CPU what stack to use
+ /*
+ * Set up the two "TSS" members which tell the CPU what stack to use
* for traps which do directly into the Guest (ie. traps at privilege
- * level 1). */
+ * level 1).
+ */
pages->state.guest_tss.sp1 = cpu->esp1;
pages->state.guest_tss.ss1 = cpu->ss1;
@@ -125,40 +135,53 @@
/* This is a dummy value we need for GCC's sake. */
unsigned int clobber;
- /* Copy the guest-specific information into this CPU's "struct
- * lguest_pages". */
+ /*
+ * Copy the guest-specific information into this CPU's "struct
+ * lguest_pages".
+ */
copy_in_guest_info(cpu, pages);
- /* Set the trap number to 256 (impossible value). If we fault while
+ /*
+ * Set the trap number to 256 (impossible value). If we fault while
* switching to the Guest (bad segment registers or bug), this will
- * cause us to abort the Guest. */
+ * cause us to abort the Guest.
+ */
cpu->regs->trapnum = 256;
- /* Now: we push the "eflags" register on the stack, then do an "lcall".
+ /*
+ * Now: we push the "eflags" register on the stack, then do an "lcall".
* This is how we change from using the kernel code segment to using
* the dedicated lguest code segment, as well as jumping into the
* Switcher.
*
* The lcall also pushes the old code segment (KERNEL_CS) onto the
* stack, then the address of this call. This stack layout happens to
- * exactly match the stack layout created by an interrupt... */
+ * exactly match the stack layout created by an interrupt...
+ */
asm volatile("pushf; lcall *lguest_entry"
- /* This is how we tell GCC that %eax ("a") and %ebx ("b")
- * are changed by this routine. The "=" means output. */
+ /*
+ * This is how we tell GCC that %eax ("a") and %ebx ("b")
+ * are changed by this routine. The "=" means output.
+ */
: "=a"(clobber), "=b"(clobber)
- /* %eax contains the pages pointer. ("0" refers to the
+ /*
+ * %eax contains the pages pointer. ("0" refers to the
* 0-th argument above, ie "a"). %ebx contains the
* physical address of the Guest's top-level page
- * directory. */
+ * directory.
+ */
: "0"(pages), "1"(__pa(cpu->lg->pgdirs[cpu->cpu_pgd].pgdir))
- /* We tell gcc that all these registers could change,
+ /*
+ * We tell gcc that all these registers could change,
* which means we don't have to save and restore them in
- * the Switcher. */
+ * the Switcher.
+ */
: "memory", "%edx", "%ecx", "%edi", "%esi");
}
/*:*/
-/*M:002 There are hooks in the scheduler which we can register to tell when we
+/*M:002
+ * There are hooks in the scheduler which we can register to tell when we
* get kicked off the CPU (preempt_notifier_register()). This would allow us
* to lazily disable SYSENTER which would regain some performance, and should
* also simplify copy_in_guest_info(). Note that we'd still need to restore
@@ -166,56 +189,72 @@
*
* We could also try using this hooks for PGE, but that might be too expensive.
*
- * The hooks were designed for KVM, but we can also put them to good use. :*/
+ * The hooks were designed for KVM, but we can also put them to good use.
+:*/
-/*H:040 This is the i386-specific code to setup and run the Guest. Interrupts
- * are disabled: we own the CPU. */
+/*H:040
+ * This is the i386-specific code to setup and run the Guest. Interrupts
+ * are disabled: we own the CPU.
+ */
void lguest_arch_run_guest(struct lg_cpu *cpu)
{
- /* Remember the awfully-named TS bit? If the Guest has asked to set it
+ /*
+ * Remember the awfully-named TS bit? If the Guest has asked to set it
* we set it now, so we can trap and pass that trap to the Guest if it
- * uses the FPU. */
+ * uses the FPU.
+ */
if (cpu->ts)
unlazy_fpu(current);
- /* SYSENTER is an optimized way of doing system calls. We can't allow
+ /*
+ * SYSENTER is an optimized way of doing system calls. We can't allow
* it because it always jumps to privilege level 0. A normal Guest
* won't try it because we don't advertise it in CPUID, but a malicious
* Guest (or malicious Guest userspace program) could, so we tell the
- * CPU to disable it before running the Guest. */
+ * CPU to disable it before running the Guest.
+ */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
- /* Now we actually run the Guest. It will return when something
+ /*
+ * Now we actually run the Guest. It will return when something
* interesting happens, and we can examine its registers to see what it
- * was doing. */
+ * was doing.
+ */
run_guest_once(cpu, lguest_pages(raw_smp_processor_id()));
- /* Note that the "regs" structure contains two extra entries which are
+ /*
+ * Note that the "regs" structure contains two extra entries which are
* not really registers: a trap number which says what interrupt or
* trap made the switcher code come back, and an error code which some
- * traps set. */
+ * traps set.
+ */
/* Restore SYSENTER if it's supposed to be on. */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
- /* If the Guest page faulted, then the cr2 register will tell us the
+ /*
+ * If the Guest page faulted, then the cr2 register will tell us the
* bad virtual address. We have to grab this now, because once we
* re-enable interrupts an interrupt could fault and thus overwrite
- * cr2, or we could even move off to a different CPU. */
+ * cr2, or we could even move off to a different CPU.
+ */
if (cpu->regs->trapnum == 14)
cpu->arch.last_pagefault = read_cr2();
- /* Similarly, if we took a trap because the Guest used the FPU,
+ /*
+ * Similarly, if we took a trap because the Guest used the FPU,
* we have to restore the FPU it expects to see.
* math_state_restore() may sleep and we may even move off to
* a different CPU. So all the critical stuff should be done
- * before this. */
+ * before this.
+ */
else if (cpu->regs->trapnum == 7)
math_state_restore();
}
-/*H:130 Now we've examined the hypercall code; our Guest can make requests.
+/*H:130
+ * Now we've examined the hypercall code; our Guest can make requests.
* Our Guest is usually so well behaved; it never tries to do things it isn't
* allowed to, and uses hypercalls instead. Unfortunately, Linux's paravirtual
* infrastructure isn't quite complete, because it doesn't contain replacements
@@ -225,26 +264,33 @@
*
* When the Guest uses one of these instructions, we get a trap (General
* Protection Fault) and come here. We see if it's one of those troublesome
- * instructions and skip over it. We return true if we did. */
+ * instructions and skip over it. We return true if we did.
+ */
static int emulate_insn(struct lg_cpu *cpu)
{
u8 insn;
unsigned int insnlen = 0, in = 0, shift = 0;
- /* The eip contains the *virtual* address of the Guest's instruction:
- * guest_pa just subtracts the Guest's page_offset. */
+ /*
+ * The eip contains the *virtual* address of the Guest's instruction:
+ * guest_pa just subtracts the Guest's page_offset.
+ */
unsigned long physaddr = guest_pa(cpu, cpu->regs->eip);
- /* This must be the Guest kernel trying to do something, not userspace!
+ /*
+ * This must be the Guest kernel trying to do something, not userspace!
* The bottom two bits of the CS segment register are the privilege
- * level. */
+ * level.
+ */
if ((cpu->regs->cs & 3) != GUEST_PL)
return 0;
/* Decoding x86 instructions is icky. */
insn = lgread(cpu, physaddr, u8);
- /* 0x66 is an "operand prefix". It means it's using the upper 16 bits
- of the eax register. */
+ /*
+ * 0x66 is an "operand prefix". It means it's using the upper 16 bits
+ * of the eax register.
+ */
if (insn == 0x66) {
shift = 16;
/* The instruction is 1 byte so far, read the next byte. */
@@ -252,8 +298,10 @@
insn = lgread(cpu, physaddr + insnlen, u8);
}
- /* We can ignore the lower bit for the moment and decode the 4 opcodes
- * we need to emulate. */
+ /*
+ * We can ignore the lower bit for the moment and decode the 4 opcodes
+ * we need to emulate.
+ */
switch (insn & 0xFE) {
case 0xE4: /* in <next byte>,%al */
insnlen += 2;
@@ -274,9 +322,11 @@
return 0;
}
- /* If it was an "IN" instruction, they expect the result to be read
+ /*
+ * If it was an "IN" instruction, they expect the result to be read
* into %eax, so we change %eax. We always return all-ones, which
- * traditionally means "there's nothing there". */
+ * traditionally means "there's nothing there".
+ */
if (in) {
/* Lower bit tells is whether it's a 16 or 32 bit access */
if (insn & 0x1)
@@ -290,7 +340,8 @@
return 1;
}
-/* Our hypercalls mechanism used to be based on direct software interrupts.
+/*
+ * Our hypercalls mechanism used to be based on direct software interrupts.
* After Anthony's "Refactor hypercall infrastructure" kvm patch, we decided to
* change over to using kvm hypercalls.
*
@@ -318,16 +369,20 @@
*/
static void rewrite_hypercall(struct lg_cpu *cpu)
{
- /* This are the opcodes we use to patch the Guest. The opcode for "int
+ /*
+ * This are the opcodes we use to patch the Guest. The opcode for "int
* $0x1f" is "0xcd 0x1f" but vmcall instruction is 3 bytes long, so we
- * complete the sequence with a NOP (0x90). */
+ * complete the sequence with a NOP (0x90).
+ */
u8 insn[3] = {0xcd, 0x1f, 0x90};
__lgwrite(cpu, guest_pa(cpu, cpu->regs->eip), insn, sizeof(insn));
- /* The above write might have caused a copy of that page to be made
+ /*
+ * The above write might have caused a copy of that page to be made
* (if it was read-only). We need to make sure the Guest has
* up-to-date pagetables. As this doesn't happen often, we can just
- * drop them all. */
+ * drop them all.
+ */
guest_pagetable_clear_all(cpu);
}
@@ -335,9 +390,11 @@
{
u8 insn[3];
- /* This must be the Guest kernel trying to do something.
+ /*
+ * This must be the Guest kernel trying to do something.
* The bottom two bits of the CS segment register are the privilege
- * level. */
+ * level.
+ */
if ((cpu->regs->cs & 3) != GUEST_PL)
return false;
@@ -351,86 +408,105 @@
{
switch (cpu->regs->trapnum) {
case 13: /* We've intercepted a General Protection Fault. */
- /* Check if this was one of those annoying IN or OUT
+ /*
+ * Check if this was one of those annoying IN or OUT
* instructions which we need to emulate. If so, we just go
- * back into the Guest after we've done it. */
+ * back into the Guest after we've done it.
+ */
if (cpu->regs->errcode == 0) {
if (emulate_insn(cpu))
return;
}
- /* If KVM is active, the vmcall instruction triggers a
- * General Protection Fault. Normally it triggers an
- * invalid opcode fault (6): */
+ /*
+ * If KVM is active, the vmcall instruction triggers a General
+ * Protection Fault. Normally it triggers an invalid opcode
+ * fault (6):
+ */
case 6:
- /* We need to check if ring == GUEST_PL and
- * faulting instruction == vmcall. */
+ /*
+ * We need to check if ring == GUEST_PL and faulting
+ * instruction == vmcall.
+ */
if (is_hypercall(cpu)) {
rewrite_hypercall(cpu);
return;
}
break;
case 14: /* We've intercepted a Page Fault. */
- /* The Guest accessed a virtual address that wasn't mapped.
+ /*
+ * The Guest accessed a virtual address that wasn't mapped.
* This happens a lot: we don't actually set up most of the page
* tables for the Guest at all when we start: as it runs it asks
* for more and more, and we set them up as required. In this
* case, we don't even tell the Guest that the fault happened.
*
* The errcode tells whether this was a read or a write, and
- * whether kernel or userspace code. */
+ * whether kernel or userspace code.
+ */
if (demand_page(cpu, cpu->arch.last_pagefault,
cpu->regs->errcode))
return;
- /* OK, it's really not there (or not OK): the Guest needs to
+ /*
+ * OK, it's really not there (or not OK): the Guest needs to
* know. We write out the cr2 value so it knows where the
* fault occurred.
*
* Note that if the Guest were really messed up, this could
* happen before it's done the LHCALL_LGUEST_INIT hypercall, so
- * lg->lguest_data could be NULL */
+ * lg->lguest_data could be NULL
+ */
if (cpu->lg->lguest_data &&
put_user(cpu->arch.last_pagefault,
&cpu->lg->lguest_data->cr2))
kill_guest(cpu, "Writing cr2");
break;
case 7: /* We've intercepted a Device Not Available fault. */
- /* If the Guest doesn't want to know, we already restored the
- * Floating Point Unit, so we just continue without telling
- * it. */
+ /*
+ * If the Guest doesn't want to know, we already restored the
+ * Floating Point Unit, so we just continue without telling it.
+ */
if (!cpu->ts)
return;
break;
case 32 ... 255:
- /* These values mean a real interrupt occurred, in which case
+ /*
+ * These values mean a real interrupt occurred, in which case
* the Host handler has already been run. We just do a
* friendly check if another process should now be run, then
- * return to run the Guest again */
+ * return to run the Guest again
+ */
cond_resched();
return;
case LGUEST_TRAP_ENTRY:
- /* Our 'struct hcall_args' maps directly over our regs: we set
- * up the pointer now to indicate a hypercall is pending. */
+ /*
+ * Our 'struct hcall_args' maps directly over our regs: we set
+ * up the pointer now to indicate a hypercall is pending.
+ */
cpu->hcall = (struct hcall_args *)cpu->regs;
return;
}
/* We didn't handle the trap, so it needs to go to the Guest. */
if (!deliver_trap(cpu, cpu->regs->trapnum))
- /* If the Guest doesn't have a handler (either it hasn't
+ /*
+ * If the Guest doesn't have a handler (either it hasn't
* registered any yet, or it's one of the faults we don't let
- * it handle), it dies with this cryptic error message. */
+ * it handle), it dies with this cryptic error message.
+ */
kill_guest(cpu, "unhandled trap %li at %#lx (%#lx)",
cpu->regs->trapnum, cpu->regs->eip,
cpu->regs->trapnum == 14 ? cpu->arch.last_pagefault
: cpu->regs->errcode);
}
-/* Now we can look at each of the routines this calls, in increasing order of
+/*
+ * Now we can look at each of the routines this calls, in increasing order of
* complexity: do_hypercalls(), emulate_insn(), maybe_do_interrupt(),
* deliver_trap() and demand_page(). After all those, we'll be ready to
* examine the Switcher, and our philosophical understanding of the Host/Guest
- * duality will be complete. :*/
+ * duality will be complete.
+:*/
static void adjust_pge(void *on)
{
if (on)
@@ -439,13 +515,16 @@
write_cr4(read_cr4() & ~X86_CR4_PGE);
}
-/*H:020 Now the Switcher is mapped and every thing else is ready, we need to do
- * some more i386-specific initialization. */
+/*H:020
+ * Now the Switcher is mapped and every thing else is ready, we need to do
+ * some more i386-specific initialization.
+ */
void __init lguest_arch_host_init(void)
{
int i;
- /* Most of the i386/switcher.S doesn't care that it's been moved; on
+ /*
+ * Most of the i386/switcher.S doesn't care that it's been moved; on
* Intel, jumps are relative, and it doesn't access any references to
* external code or data.
*
@@ -453,7 +532,8 @@
* addresses are placed in a table (default_idt_entries), so we need to
* update the table with the new addresses. switcher_offset() is a
* convenience function which returns the distance between the
- * compiled-in switcher code and the high-mapped copy we just made. */
+ * compiled-in switcher code and the high-mapped copy we just made.
+ */
for (i = 0; i < IDT_ENTRIES; i++)
default_idt_entries[i] += switcher_offset();
@@ -468,63 +548,81 @@
for_each_possible_cpu(i) {
/* lguest_pages() returns this CPU's two pages. */
struct lguest_pages *pages = lguest_pages(i);
- /* This is a convenience pointer to make the code fit one
- * statement to a line. */
+ /* This is a convenience pointer to make the code neater. */
struct lguest_ro_state *state = &pages->state;
- /* The Global Descriptor Table: the Host has a different one
+ /*
+ * The Global Descriptor Table: the Host has a different one
* for each CPU. We keep a descriptor for the GDT which says
* where it is and how big it is (the size is actually the last
- * byte, not the size, hence the "-1"). */
+ * byte, not the size, hence the "-1").
+ */
state->host_gdt_desc.size = GDT_SIZE-1;
state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
- /* All CPUs on the Host use the same Interrupt Descriptor
+ /*
+ * All CPUs on the Host use the same Interrupt Descriptor
* Table, so we just use store_idt(), which gets this CPU's IDT
- * descriptor. */
+ * descriptor.
+ */
store_idt(&state->host_idt_desc);
- /* The descriptors for the Guest's GDT and IDT can be filled
+ /*
+ * The descriptors for the Guest's GDT and IDT can be filled
* out now, too. We copy the GDT & IDT into ->guest_gdt and
- * ->guest_idt before actually running the Guest. */
+ * ->guest_idt before actually running the Guest.
+ */
state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
state->guest_idt_desc.address = (long)&state->guest_idt;
state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
state->guest_gdt_desc.address = (long)&state->guest_gdt;
- /* We know where we want the stack to be when the Guest enters
+ /*
+ * We know where we want the stack to be when the Guest enters
* the Switcher: in pages->regs. The stack grows upwards, so
- * we start it at the end of that structure. */
+ * we start it at the end of that structure.
+ */
state->guest_tss.sp0 = (long)(&pages->regs + 1);
- /* And this is the GDT entry to use for the stack: we keep a
- * couple of special LGUEST entries. */
+ /*
+ * And this is the GDT entry to use for the stack: we keep a
+ * couple of special LGUEST entries.
+ */
state->guest_tss.ss0 = LGUEST_DS;
- /* x86 can have a finegrained bitmap which indicates what I/O
+ /*
+ * x86 can have a finegrained bitmap which indicates what I/O
* ports the process can use. We set it to the end of our
- * structure, meaning "none". */
+ * structure, meaning "none".
+ */
state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
- /* Some GDT entries are the same across all Guests, so we can
- * set them up now. */
+ /*
+ * Some GDT entries are the same across all Guests, so we can
+ * set them up now.
+ */
setup_default_gdt_entries(state);
/* Most IDT entries are the same for all Guests, too.*/
setup_default_idt_entries(state, default_idt_entries);
- /* The Host needs to be able to use the LGUEST segments on this
- * CPU, too, so put them in the Host GDT. */
+ /*
+ * The Host needs to be able to use the LGUEST segments on this
+ * CPU, too, so put them in the Host GDT.
+ */
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
}
- /* In the Switcher, we want the %cs segment register to use the
+ /*
+ * In the Switcher, we want the %cs segment register to use the
* LGUEST_CS GDT entry: we've put that in the Host and Guest GDTs, so
* it will be undisturbed when we switch. To change %cs and jump we
- * need this structure to feed to Intel's "lcall" instruction. */
+ * need this structure to feed to Intel's "lcall" instruction.
+ */
lguest_entry.offset = (long)switch_to_guest + switcher_offset();
lguest_entry.segment = LGUEST_CS;
- /* Finally, we need to turn off "Page Global Enable". PGE is an
+ /*
+ * Finally, we need to turn off "Page Global Enable". PGE is an
* optimization where page table entries are specially marked to show
* they never change. The Host kernel marks all the kernel pages this
* way because it's always present, even when userspace is running.
@@ -534,16 +632,21 @@
* you'll get really weird bugs that you'll chase for two days.
*
* I used to turn PGE off every time we switched to the Guest and back
- * on when we return, but that slowed the Switcher down noticibly. */
+ * on when we return, but that slowed the Switcher down noticibly.
+ */
- /* We don't need the complexity of CPUs coming and going while we're
- * doing this. */
+ /*
+ * We don't need the complexity of CPUs coming and going while we're
+ * doing this.
+ */
get_online_cpus();
if (cpu_has_pge) { /* We have a broader idea of "global". */
/* Remember that this was originally set (for cleanup). */
cpu_had_pge = 1;
- /* adjust_pge is a helper function which sets or unsets the PGE
- * bit on its CPU, depending on the argument (0 == unset). */
+ /*
+ * adjust_pge is a helper function which sets or unsets the PGE
+ * bit on its CPU, depending on the argument (0 == unset).
+ */
on_each_cpu(adjust_pge, (void *)0, 1);
/* Turn off the feature in the global feature set. */
clear_cpu_cap(&boot_cpu_data, X86_FEATURE_PGE);
@@ -590,26 +693,32 @@
{
u32 tsc_speed;
- /* The pointer to the Guest's "struct lguest_data" is the only argument.
- * We check that address now. */
+ /*
+ * The pointer to the Guest's "struct lguest_data" is the only argument.
+ * We check that address now.
+ */
if (!lguest_address_ok(cpu->lg, cpu->hcall->arg1,
sizeof(*cpu->lg->lguest_data)))
return -EFAULT;
- /* Having checked it, we simply set lg->lguest_data to point straight
+ /*
+ * Having checked it, we simply set lg->lguest_data to point straight
* into the Launcher's memory at the right place and then use
* copy_to_user/from_user from now on, instead of lgread/write. I put
* this in to show that I'm not immune to writing stupid
- * optimizations. */
+ * optimizations.
+ */
cpu->lg->lguest_data = cpu->lg->mem_base + cpu->hcall->arg1;
- /* We insist that the Time Stamp Counter exist and doesn't change with
+ /*
+ * We insist that the Time Stamp Counter exist and doesn't change with
* cpu frequency. Some devious chip manufacturers decided that TSC
* changes could be handled in software. I decided that time going
* backwards might be good for benchmarks, but it's bad for users.
*
* We also insist that the TSC be stable: the kernel detects unreliable
- * TSCs for its own purposes, and we use that here. */
+ * TSCs for its own purposes, and we use that here.
+ */
if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
tsc_speed = tsc_khz;
else
@@ -625,38 +734,47 @@
}
/*:*/
-/*L:030 lguest_arch_setup_regs()
+/*L:030
+ * lguest_arch_setup_regs()
*
* Most of the Guest's registers are left alone: we used get_zeroed_page() to
- * allocate the structure, so they will be 0. */
+ * allocate the structure, so they will be 0.
+ */
void lguest_arch_setup_regs(struct lg_cpu *cpu, unsigned long start)
{
struct lguest_regs *regs = cpu->regs;
- /* There are four "segment" registers which the Guest needs to boot:
+ /*
+ * There are four "segment" registers which the Guest needs to boot:
* The "code segment" register (cs) refers to the kernel code segment
* __KERNEL_CS, and the "data", "extra" and "stack" segment registers
* refer to the kernel data segment __KERNEL_DS.
*
* The privilege level is packed into the lower bits. The Guest runs
- * at privilege level 1 (GUEST_PL).*/
+ * at privilege level 1 (GUEST_PL).
+ */
regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
regs->cs = __KERNEL_CS|GUEST_PL;
- /* The "eflags" register contains miscellaneous flags. Bit 1 (0x002)
+ /*
+ * The "eflags" register contains miscellaneous flags. Bit 1 (0x002)
* is supposed to always be "1". Bit 9 (0x200) controls whether
* interrupts are enabled. We always leave interrupts enabled while
- * running the Guest. */
+ * running the Guest.
+ */
regs->eflags = X86_EFLAGS_IF | 0x2;
- /* The "Extended Instruction Pointer" register says where the Guest is
- * running. */
+ /*
+ * The "Extended Instruction Pointer" register says where the Guest is
+ * running.
+ */
regs->eip = start;
- /* %esi points to our boot information, at physical address 0, so don't
- * touch it. */
+ /*
+ * %esi points to our boot information, at physical address 0, so don't
+ * touch it.
+ */
- /* There are a couple of GDT entries the Guest expects when first
- * booting. */
+ /* There are a couple of GDT entries the Guest expects at boot. */
setup_guest_gdt(cpu);
}
diff --git a/drivers/lguest/x86/switcher_32.S b/drivers/lguest/x86/switcher_32.S
index 3fc1531..6dec097 100644
--- a/drivers/lguest/x86/switcher_32.S
+++ b/drivers/lguest/x86/switcher_32.S
@@ -1,12 +1,15 @@
-/*P:900 This is the Switcher: code which sits at 0xFFC00000 astride both the
+/*P:900
+ * This is the Switcher: code which sits at 0xFFC00000 astride both the
* Host and Guest to do the low-level Guest<->Host switch. It is as simple as
* it can be made, but it's naturally very specific to x86.
*
* You have now completed Preparation. If this has whet your appetite; if you
* are feeling invigorated and refreshed then the next, more challenging stage
- * can be found in "make Guest". :*/
+ * can be found in "make Guest".
+ :*/
-/*M:012 Lguest is meant to be simple: my rule of thumb is that 1% more LOC must
+/*M:012
+ * Lguest is meant to be simple: my rule of thumb is that 1% more LOC must
* gain at least 1% more performance. Since neither LOC nor performance can be
* measured beforehand, it generally means implementing a feature then deciding
* if it's worth it. And once it's implemented, who can say no?
@@ -31,11 +34,14 @@
* Host (which is actually really easy).
*
* Two questions remain. Would the performance gain outweigh the complexity?
- * And who would write the verse documenting it? :*/
+ * And who would write the verse documenting it?
+:*/
-/*M:011 Lguest64 handles NMI. This gave me NMI envy (until I looked at their
+/*M:011
+ * Lguest64 handles NMI. This gave me NMI envy (until I looked at their
* code). It's worth doing though, since it would let us use oprofile in the
- * Host when a Guest is running. :*/
+ * Host when a Guest is running.
+:*/
/*S:100
* Welcome to the Switcher itself!