@@ -19,6 +19,10 @@
#ifndef ARM_TARGET_CPU_H
#define ARM_TARGET_CPU_H
+/* We need to be able to map the commpage.
+ See validate_guest_space in linux-user/elfload.c. */
+#define MAX_RESERVED_VA 0xfff00000ul
+
static inline void cpu_clone_regs(CPUARMState *env, target_ulong newsp)
{
if (newsp) {
@@ -15,7 +15,11 @@
#else
#define TARGET_LONG_BITS 32
#define TARGET_PHYS_ADDR_SPACE_BITS 40
-#define TARGET_VIRT_ADDR_SPACE_BITS 32
+# ifdef CONFIG_USER_ONLY
+# define TARGET_VIRT_ADDR_SPACE_BITS 31
+# else
+# define TARGET_VIRT_ADDR_SPACE_BITS 32
+#endif
#endif
/* Masks used to mark instructions to indicate which ISA level they
@@ -227,7 +227,11 @@ qemu_irq *nios2_cpu_pic_init(Nios2CPU *cpu);
void nios2_check_interrupts(CPUNios2State *env);
#define TARGET_PHYS_ADDR_SPACE_BITS 32
-#define TARGET_VIRT_ADDR_SPACE_BITS 32
+#ifdef CONFIG_USER_ONLY
+# define TARGET_VIRT_ADDR_SPACE_BITS 31
+#else
+# define TARGET_VIRT_ADDR_SPACE_BITS 32
+#endif
#define cpu_init(cpu_model) CPU(cpu_nios2_init(cpu_model))
@@ -60,23 +60,38 @@ do { \
} \
} while (0)
-#if (TARGET_LONG_BITS == 32) && (HOST_LONG_BITS == 64)
/*
* When running 32-on-64 we should make sure we can fit all of the possible
* guest address space into a contiguous chunk of virtual host memory.
*
* This way we will never overlap with our own libraries or binaries or stack
* or anything else that QEMU maps.
+ *
+ * Many cpus reserve the high bit (or more than one for some 64-bit cpus)
+ * of the address for the kernel. Some cpus rely on this and user space
+ * uses the high bit(s) for pointer tagging and the like. For them, we
+ * must preserve the expected address space.
*/
-# if defined(TARGET_MIPS) || defined(TARGET_NIOS2)
-/*
- * MIPS only supports 31 bits of virtual address space for user space.
- * Nios2 also only supports 31 bits.
- */
-unsigned long reserved_va = 0x77000000;
+#ifndef MAX_RESERVED_VA
+# if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
+# if TARGET_VIRT_ADDR_SPACE_BITS == 32 && \
+ (TARGET_LONG_BITS == 32 || defined(TARGET_ABI32))
+/* There are a number of places where we assign reserved_va to a variable
+ of type abi_ulong and expect it to fit. Avoid the last page. */
+# define MAX_RESERVED_VA (0xfffffffful & TARGET_PAGE_MASK)
+# else
+# define MAX_RESERVED_VA (1ul << TARGET_VIRT_ADDR_SPACE_BITS)
+# endif
# else
-unsigned long reserved_va = 0xf7000000;
+# define MAX_RESERVED_VA 0
# endif
+#endif
+
+/* That said, reserving *too* much vm space via mmap can run into problems
+ with rlimits, oom due to page table creation, etc. We will still try it,
+ if directed by the command-line option, but not by default. */
+#if HOST_LONG_BITS == 64 && TARGET_VIRT_ADDR_SPACE_BITS <= 32
+unsigned long reserved_va = MAX_RESERVED_VA;
#else
unsigned long reserved_va;
#endif
@@ -3976,11 +3991,8 @@ static void handle_arg_reserved_va(const char *arg)
unsigned long unshifted = reserved_va;
p++;
reserved_va <<= shift;
- if (((reserved_va >> shift) != unshifted)
-#if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
- || (reserved_va > (1ul << TARGET_VIRT_ADDR_SPACE_BITS))
-#endif
- ) {
+ if (reserved_va >> shift != unshifted
+ || (MAX_RESERVED_VA && reserved_va > MAX_RESERVED_VA)) {
fprintf(stderr, "Reserved virtual address too big\n");
exit(EXIT_FAILURE);
}
We had a check using TARGET_VIRT_ADDR_SPACE_BITS to make sure that the allocation coming in from the command-line option was not too large, but that didn't include target-specific knowledge about other restrictions on user-space. Remove several target-specific hacks in linux-user/main.c. For MIPS and Nios, we can replace them with proper adjustments to the respective target's TARGET_VIRT_ADDR_SPACE_BITS definition. For ARM, we had no existing ifdef but I suspect that the current default value of 0xf7000000 was chosen with this in mind. Define a workable value in linux-user/arm/, and also document why the special case is required. Signed-off-by: Richard Henderson <rth@twiddle.net> --- linux-user/arm/target_cpu.h | 4 ++++ target/mips/mips-defs.h | 6 +++++- target/nios2/cpu.h | 6 +++++- linux-user/main.c | 38 +++++++++++++++++++++++++------------- 4 files changed, 39 insertions(+), 15 deletions(-)