Commit 18e80c55 authored by Richard Henderson's avatar Richard Henderson Committed by Riku Voipio
Browse files

linux-user: Tidy and enforce reserved_va initialization 



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: default avatarRichard Henderson <rth@twiddle.net>
Reviewed-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Message-Id: <20170708025030.15845-3-rth@twiddle.net>
Signed-off-by: default avatarRiku Voipio <riku.voipio@linaro.org>
parent de258eb0

linux-user/arm/target_cpu.h

+4 −0
Original line number Diff line number Diff line
@@ -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  0xffff0000ul



static inline void cpu_clone_regs(CPUARMState *env, target_ulong newsp)

{

    if (newsp) {

linux-user/main.c

+25 −13
Original line number Diff line number Diff line
@@ -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
@@ -3978,11 +3993,8 @@ 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);

        }

target/mips/mips-defs.h

+5 −1
Original line number Diff line number Diff line
@@ -15,8 +15,12 @@ 
#else

#define TARGET_LONG_BITS 32

#define TARGET_PHYS_ADDR_SPACE_BITS 40

# 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

   were introduced in. */

target/nios2/cpu.h

+5 −1
Original line number Diff line number Diff line
@@ -226,7 +226,11 @@ qemu_irq *nios2_cpu_pic_init(Nios2CPU *cpu); 
void nios2_check_interrupts(CPUNios2State *env);



#define TARGET_PHYS_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_generic_init(TYPE_NIOS2_CPU, cpu_model)