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Message-Id: <1423200112-5354-3-git-send-email-rusty@rustcorp.com.au>
Date: Fri, 6 Feb 2015 15:51:45 +1030
From: Rusty Russell <rusty@...tcorp.com.au>
To: "lkml" <linux-kernel@...r.kernel.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Subject: [PATCH 02/29] lguest: add operations to get/set a register from the Launcher.
We use the ptrace API struct, and we currently don't let them set
anything but the normal registers (we'd have to filter the others).
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
drivers/lguest/core.c | 8 +++++++
drivers/lguest/lg.h | 3 +++
drivers/lguest/lguest_user.c | 49 +++++++++++++++++++++++++++++++++++++++++
drivers/lguest/x86/core.c | 46 ++++++++++++++++++++++++++++++++++++++
include/linux/lguest_launcher.h | 2 ++
5 files changed, 108 insertions(+)
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 6590558d1d31..cdb2f9aa5860 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -208,6 +208,14 @@ void __lgwrite(struct lg_cpu *cpu, unsigned long addr, const void *b,
*/
int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
{
+ /* If the launcher asked for a register with LHREQ_GETREG */
+ if (cpu->reg_read) {
+ if (put_user(*cpu->reg_read, user))
+ return -EFAULT;
+ cpu->reg_read = NULL;
+ return sizeof(*cpu->reg_read);
+ }
+
/* We stop running once the Guest is dead. */
while (!cpu->lg->dead) {
unsigned int irq;
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 2eef40be4c04..1c98bf74fd68 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -52,6 +52,8 @@ struct lg_cpu {
unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */
+ unsigned long *reg_read; /* register from LHREQ_GETREG */
+
/* At end of a page shared mapped over lguest_pages in guest. */
unsigned long regs_page;
struct lguest_regs *regs;
@@ -210,6 +212,7 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu);
int lguest_arch_init_hypercalls(struct lg_cpu *cpu);
int lguest_arch_do_hcall(struct lg_cpu *cpu, struct hcall_args *args);
void lguest_arch_setup_regs(struct lg_cpu *cpu, unsigned long start);
+unsigned long *lguest_arch_regptr(struct lg_cpu *cpu, size_t reg_off, bool any);
/* <arch>/switcher.S: */
extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 4263f4cc8c55..7f14c152dd23 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -173,6 +173,51 @@ static int attach_eventfd(struct lguest *lg, const unsigned long __user *input)
return err;
}
+/* The Launcher can get the registers, and also set some of them. */
+static int getreg_setup(struct lg_cpu *cpu, const unsigned long __user *input)
+{
+ unsigned long which;
+
+ /* We re-use the ptrace structure to specify which register to read. */
+ if (get_user(which, input) != 0)
+ return -EFAULT;
+
+ /*
+ * We set up the cpu register pointer, and their next read will
+ * actually get the value (instead of running the guest).
+ *
+ * The last argument 'true' says we can access any register.
+ */
+ cpu->reg_read = lguest_arch_regptr(cpu, which, true);
+ if (!cpu->reg_read)
+ return -ENOENT;
+
+ /* And because this is a write() call, we return the length used. */
+ return sizeof(unsigned long) * 2;
+}
+
+static int setreg(struct lg_cpu *cpu, const unsigned long __user *input)
+{
+ unsigned long which, value, *reg;
+
+ /* We re-use the ptrace structure to specify which register to read. */
+ if (get_user(which, input) != 0)
+ return -EFAULT;
+ input++;
+ if (get_user(value, input) != 0)
+ return -EFAULT;
+
+ /* The last argument 'false' means we can't access all registers. */
+ reg = lguest_arch_regptr(cpu, which, false);
+ if (!reg)
+ return -ENOENT;
+
+ *reg = value;
+
+ /* And because this is a write() call, we return the length used. */
+ return sizeof(unsigned long) * 3;
+}
+
/*L:050
* Sending an interrupt is done by writing LHREQ_IRQ and an interrupt
* number to /dev/lguest.
@@ -434,6 +479,10 @@ static ssize_t write(struct file *file, const char __user *in,
return user_send_irq(cpu, input);
case LHREQ_EVENTFD:
return attach_eventfd(lg, input);
+ case LHREQ_GETREG:
+ return getreg_setup(cpu, input);
+ case LHREQ_SETREG:
+ return setreg(cpu, input);
default:
return -EINVAL;
}
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index 922a1acbf652..f7a16b4ea456 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -181,6 +181,52 @@ static void run_guest_once(struct lg_cpu *cpu, struct lguest_pages *pages)
}
/*:*/
+unsigned long *lguest_arch_regptr(struct lg_cpu *cpu, size_t reg_off, bool any)
+{
+ switch (reg_off) {
+ case offsetof(struct pt_regs, bx):
+ return &cpu->regs->ebx;
+ case offsetof(struct pt_regs, cx):
+ return &cpu->regs->ecx;
+ case offsetof(struct pt_regs, dx):
+ return &cpu->regs->edx;
+ case offsetof(struct pt_regs, si):
+ return &cpu->regs->esi;
+ case offsetof(struct pt_regs, di):
+ return &cpu->regs->edi;
+ case offsetof(struct pt_regs, bp):
+ return &cpu->regs->ebp;
+ case offsetof(struct pt_regs, ax):
+ return &cpu->regs->eax;
+ case offsetof(struct pt_regs, ip):
+ return &cpu->regs->eip;
+ case offsetof(struct pt_regs, sp):
+ return &cpu->regs->esp;
+ }
+
+ /* Launcher can read these, but we don't allow any setting. */
+ if (any) {
+ switch (reg_off) {
+ case offsetof(struct pt_regs, ds):
+ return &cpu->regs->ds;
+ case offsetof(struct pt_regs, es):
+ return &cpu->regs->es;
+ case offsetof(struct pt_regs, fs):
+ return &cpu->regs->fs;
+ case offsetof(struct pt_regs, gs):
+ return &cpu->regs->gs;
+ case offsetof(struct pt_regs, cs):
+ return &cpu->regs->cs;
+ case offsetof(struct pt_regs, flags):
+ return &cpu->regs->eflags;
+ case offsetof(struct pt_regs, ss):
+ return &cpu->regs->ss;
+ }
+ }
+
+ return NULL;
+}
+
/*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
diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h
index 495203ff221c..f27cae27b0c1 100644
--- a/include/linux/lguest_launcher.h
+++ b/include/linux/lguest_launcher.h
@@ -63,6 +63,8 @@ enum lguest_req
LHREQ_IRQ, /* + irq */
LHREQ_BREAK, /* No longer used */
LHREQ_EVENTFD, /* + address, fd. */
+ LHREQ_GETREG, /* + offset within struct pt_regs (then read value). */
+ LHREQ_SETREG, /* + offset within struct pt_regs, value. */
};
/*
--
2.1.0
--
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