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qemu-e2k/include/exec/cpu-all.h
Eric Blake f9919116b8 osdep: Make MIN/MAX evaluate arguments only once 
I'm not aware of any immediate bugs in qemu where a second runtime
evaluation of the arguments to MIN() or MAX() causes a problem, but
proactively preventing such abuse is easier than falling prey to an
unintended case down the road.  At any rate, here's the conversation
that sparked the current patch:
https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg05718.html

Update the MIN/MAX macros to only evaluate their argument once at
runtime; this uses typeof(1 ? (a) : (b)) to ensure that we are
promoting the temporaries to the same type as the final comparison (we
have to trigger type promotion, as typeof(bitfield) won't compile; and
we can't use typeof((a) + (b)) or even typeof((a) + 0), as some of our
uses of MAX are on void* pointers where such addition is undefined).

However, we are unable to work around gcc refusing to compile ({}) in
a constant context (such as the array length of a static variable),
even when only used in the dead branch of a __builtin_choose_expr(),
so we have to provide a second macro pair MIN_CONST and MAX_CONST for
use when both arguments are known to be compile-time constants and
where the result must also be usable as a constant; this second form
evaluates arguments multiple times but that doesn't matter for
constants.  By using a void expression as the expansion if a
non-constant is presented to this second form, we can enlist the
compiler to ensure the double evaluation is not attempted on
non-constants.

Alas, as both macros now rely on compiler intrinsics, they are no
longer usable in preprocessor #if conditions; those will just have to
be open-coded or the logic rewritten into #define or runtime 'if'
conditions (but where the compiler dead-code-elimination will probably
still apply).

I tested that both gcc 10.1.1 and clang 10.0.0 produce errors for all
forms of macro mis-use.  As the errors can sometimes be cryptic, I'm
demonstrating the gcc output:

Use of MIN when MIN_CONST is needed:

In file included from /home/eblake/qemu/qemu-img.c:25:
/home/eblake/qemu/include/qemu/osdep.h:249:5: error: braced-group within expression allowed only inside a function
  249 |     ({                                                  \
      |     ^
/home/eblake/qemu/qemu-img.c:92:12: note: in expansion of macro ‘MIN’
   92 | char array[MIN(1, 2)] = "";
      |            ^~~

Use of MIN_CONST when MIN is needed:

/home/eblake/qemu/qemu-img.c: In function ‘is_allocated_sectors’:
/home/eblake/qemu/qemu-img.c:1225:15: error: void value not ignored as it ought to be
 1225 |             i = MIN_CONST(i, n);
      |               ^

Use of MIN in the preprocessor:

In file included from /home/eblake/qemu/accel/tcg/translate-all.c:20:
/home/eblake/qemu/accel/tcg/translate-all.c: In function ‘page_check_range’:
/home/eblake/qemu/include/qemu/osdep.h:249:6: error: token "{" is not valid in preprocessor expressions
  249 |     ({                                                  \
      |      ^

Fix the resulting callsites that used #if or computed a compile-time
constant min or max to use the new macros.  cpu-defs.h is interesting,
as CPU_TLB_DYN_MAX_BITS is sometimes used as a constant and sometimes
dynamic.

It may be worth improving glib's MIN/MAX definitions to be saner, but
that is a task for another day.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200625162602.700741-1-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-26 09:39:39 -04:00

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/*
* defines common to all virtual CPUs
*
* Copyright (c) 2003 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef CPU_ALL_H
#define CPU_ALL_H
#include "exec/cpu-common.h"
#include "exec/memory.h"
#include "qemu/thread.h"
#include "hw/core/cpu.h"
#include "qemu/rcu.h"
#define EXCP_INTERRUPT 0x10000 /* async interruption */
#define EXCP_HLT 0x10001 /* hlt instruction reached */
#define EXCP_DEBUG 0x10002 /* cpu stopped after a breakpoint or singlestep */
#define EXCP_HALTED 0x10003 /* cpu is halted (waiting for external event) */
#define EXCP_YIELD 0x10004 /* cpu wants to yield timeslice to another */
#define EXCP_ATOMIC 0x10005 /* stop-the-world and emulate atomic */
/* some important defines:
*
* HOST_WORDS_BIGENDIAN : if defined, the host cpu is big endian and
* otherwise little endian.
*
* TARGET_WORDS_BIGENDIAN : same for target cpu
*/
#if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN)
#define BSWAP_NEEDED
#endif
#ifdef BSWAP_NEEDED
static inline uint16_t tswap16(uint16_t s)
{
return bswap16(s);
}
static inline uint32_t tswap32(uint32_t s)
{
return bswap32(s);
}
static inline uint64_t tswap64(uint64_t s)
{
return bswap64(s);
}
static inline void tswap16s(uint16_t *s)
{
*s = bswap16(*s);
}
static inline void tswap32s(uint32_t *s)
{
*s = bswap32(*s);
}
static inline void tswap64s(uint64_t *s)
{
*s = bswap64(*s);
}
#else
static inline uint16_t tswap16(uint16_t s)
{
return s;
}
static inline uint32_t tswap32(uint32_t s)
{
return s;
}
static inline uint64_t tswap64(uint64_t s)
{
return s;
}
static inline void tswap16s(uint16_t *s)
{
}
static inline void tswap32s(uint32_t *s)
{
}
static inline void tswap64s(uint64_t *s)
{
}
#endif
#if TARGET_LONG_SIZE == 4
#define tswapl(s) tswap32(s)
#define tswapls(s) tswap32s((uint32_t *)(s))
#define bswaptls(s) bswap32s(s)
#else
#define tswapl(s) tswap64(s)
#define tswapls(s) tswap64s((uint64_t *)(s))
#define bswaptls(s) bswap64s(s)
#endif
/* Target-endianness CPU memory access functions. These fit into the
* {ld,st}{type}{sign}{size}{endian}_p naming scheme described in bswap.h.
*/
#if defined(TARGET_WORDS_BIGENDIAN)
#define lduw_p(p) lduw_be_p(p)
#define ldsw_p(p) ldsw_be_p(p)
#define ldl_p(p) ldl_be_p(p)
#define ldq_p(p) ldq_be_p(p)
#define ldfl_p(p) ldfl_be_p(p)
#define ldfq_p(p) ldfq_be_p(p)
#define stw_p(p, v) stw_be_p(p, v)
#define stl_p(p, v) stl_be_p(p, v)
#define stq_p(p, v) stq_be_p(p, v)
#define stfl_p(p, v) stfl_be_p(p, v)
#define stfq_p(p, v) stfq_be_p(p, v)
#define ldn_p(p, sz) ldn_be_p(p, sz)
#define stn_p(p, sz, v) stn_be_p(p, sz, v)
#else
#define lduw_p(p) lduw_le_p(p)
#define ldsw_p(p) ldsw_le_p(p)
#define ldl_p(p) ldl_le_p(p)
#define ldq_p(p) ldq_le_p(p)
#define ldfl_p(p) ldfl_le_p(p)
#define ldfq_p(p) ldfq_le_p(p)
#define stw_p(p, v) stw_le_p(p, v)
#define stl_p(p, v) stl_le_p(p, v)
#define stq_p(p, v) stq_le_p(p, v)
#define stfl_p(p, v) stfl_le_p(p, v)
#define stfq_p(p, v) stfq_le_p(p, v)
#define ldn_p(p, sz) ldn_le_p(p, sz)
#define stn_p(p, sz, v) stn_le_p(p, sz, v)
#endif
/* MMU memory access macros */
#if defined(CONFIG_USER_ONLY)
#include "exec/user/abitypes.h"
/* On some host systems the guest address space is reserved on the host.
* This allows the guest address space to be offset to a convenient location.
*/
extern unsigned long guest_base;
extern bool have_guest_base;
extern unsigned long reserved_va;
/*
* Limit the guest addresses as best we can.
*
* When not using -R reserved_va, we cannot really limit the guest
* to less address space than the host. For 32-bit guests, this
* acts as a sanity check that we're not giving the guest an address
* that it cannot even represent. For 64-bit guests... the address
* might not be what the real kernel would give, but it is at least
* representable in the guest.
*
* TODO: Improve address allocation to avoid this problem, and to
* avoid setting bits at the top of guest addresses that might need
* to be used for tags.
*/
#define GUEST_ADDR_MAX_ \
((MIN_CONST(TARGET_VIRT_ADDR_SPACE_BITS, TARGET_ABI_BITS) <= 32) ? \
UINT32_MAX : ~0ul)
#define GUEST_ADDR_MAX (reserved_va ? reserved_va - 1 : GUEST_ADDR_MAX_)
#else
#include "exec/hwaddr.h"
#define SUFFIX
#define ARG1 as
#define ARG1_DECL AddressSpace *as
#define TARGET_ENDIANNESS
#include "exec/memory_ldst.inc.h"
#define SUFFIX _cached_slow
#define ARG1 cache
#define ARG1_DECL MemoryRegionCache *cache
#define TARGET_ENDIANNESS
#include "exec/memory_ldst.inc.h"
static inline void stl_phys_notdirty(AddressSpace *as, hwaddr addr, uint32_t val)
{
address_space_stl_notdirty(as, addr, val,
MEMTXATTRS_UNSPECIFIED, NULL);
}
#define SUFFIX
#define ARG1 as
#define ARG1_DECL AddressSpace *as
#define TARGET_ENDIANNESS
#include "exec/memory_ldst_phys.inc.h"
/* Inline fast path for direct RAM access. */
#define ENDIANNESS
#include "exec/memory_ldst_cached.inc.h"
#define SUFFIX _cached
#define ARG1 cache
#define ARG1_DECL MemoryRegionCache *cache
#define TARGET_ENDIANNESS
#include "exec/memory_ldst_phys.inc.h"
#endif
/* page related stuff */
#ifdef TARGET_PAGE_BITS_VARY
typedef struct {
bool decided;
int bits;
target_long mask;
} TargetPageBits;
#if defined(CONFIG_ATTRIBUTE_ALIAS) || !defined(IN_EXEC_VARY)
extern const TargetPageBits target_page;
#else
extern TargetPageBits target_page;
#endif
#ifdef CONFIG_DEBUG_TCG
#define TARGET_PAGE_BITS ({ assert(target_page.decided); target_page.bits; })
#define TARGET_PAGE_MASK ({ assert(target_page.decided); target_page.mask; })
#else
#define TARGET_PAGE_BITS target_page.bits
#define TARGET_PAGE_MASK target_page.mask
#endif
#define TARGET_PAGE_SIZE (-(int)TARGET_PAGE_MASK)
#else
#define TARGET_PAGE_BITS_MIN TARGET_PAGE_BITS
#define TARGET_PAGE_SIZE (1 << TARGET_PAGE_BITS)
#define TARGET_PAGE_MASK ((target_long)-1 << TARGET_PAGE_BITS)
#endif
#define TARGET_PAGE_ALIGN(addr) ROUND_UP((addr), TARGET_PAGE_SIZE)
/* Using intptr_t ensures that qemu_*_page_mask is sign-extended even
* when intptr_t is 32-bit and we are aligning a long long.
*/
extern uintptr_t qemu_host_page_size;
extern intptr_t qemu_host_page_mask;
#define HOST_PAGE_ALIGN(addr) ROUND_UP((addr), qemu_host_page_size)
#define REAL_HOST_PAGE_ALIGN(addr) ROUND_UP((addr), qemu_real_host_page_size)
/* same as PROT_xxx */
#define PAGE_READ 0x0001
#define PAGE_WRITE 0x0002
#define PAGE_EXEC 0x0004
#define PAGE_BITS (PAGE_READ | PAGE_WRITE | PAGE_EXEC)
#define PAGE_VALID 0x0008
/* original state of the write flag (used when tracking self-modifying
code */
#define PAGE_WRITE_ORG 0x0010
/* Invalidate the TLB entry immediately, helpful for s390x
* Low-Address-Protection. Used with PAGE_WRITE in tlb_set_page_with_attrs() */
#define PAGE_WRITE_INV 0x0040
#if defined(CONFIG_BSD) && defined(CONFIG_USER_ONLY)
/* FIXME: Code that sets/uses this is broken and needs to go away. */
#define PAGE_RESERVED 0x0020
#endif
#if defined(CONFIG_USER_ONLY)
void page_dump(FILE *f);
typedef int (*walk_memory_regions_fn)(void *, target_ulong,
target_ulong, unsigned long);
int walk_memory_regions(void *, walk_memory_regions_fn);
int page_get_flags(target_ulong address);
void page_set_flags(target_ulong start, target_ulong end, int flags);
int page_check_range(target_ulong start, target_ulong len, int flags);
#endif
CPUArchState *cpu_copy(CPUArchState *env);
/* Flags for use in ENV->INTERRUPT_PENDING.
The numbers assigned here are non-sequential in order to preserve
binary compatibility with the vmstate dump. Bit 0 (0x0001) was
previously used for CPU_INTERRUPT_EXIT, and is cleared when loading
the vmstate dump. */
/* External hardware interrupt pending. This is typically used for
interrupts from devices. */
#define CPU_INTERRUPT_HARD 0x0002
/* Exit the current TB. This is typically used when some system-level device
makes some change to the memory mapping. E.g. the a20 line change. */
#define CPU_INTERRUPT_EXITTB 0x0004
/* Halt the CPU. */
#define CPU_INTERRUPT_HALT 0x0020
/* Debug event pending. */
#define CPU_INTERRUPT_DEBUG 0x0080
/* Reset signal. */
#define CPU_INTERRUPT_RESET 0x0400
/* Several target-specific external hardware interrupts. Each target/cpu.h
should define proper names based on these defines. */
#define CPU_INTERRUPT_TGT_EXT_0 0x0008
#define CPU_INTERRUPT_TGT_EXT_1 0x0010
#define CPU_INTERRUPT_TGT_EXT_2 0x0040
#define CPU_INTERRUPT_TGT_EXT_3 0x0200
#define CPU_INTERRUPT_TGT_EXT_4 0x1000
/* Several target-specific internal interrupts. These differ from the
preceding target-specific interrupts in that they are intended to
originate from within the cpu itself, typically in response to some
instruction being executed. These, therefore, are not masked while
single-stepping within the debugger. */
#define CPU_INTERRUPT_TGT_INT_0 0x0100
#define CPU_INTERRUPT_TGT_INT_1 0x0800
#define CPU_INTERRUPT_TGT_INT_2 0x2000
/* First unused bit: 0x4000. */
/* The set of all bits that should be masked when single-stepping. */
#define CPU_INTERRUPT_SSTEP_MASK \
(CPU_INTERRUPT_HARD \
| CPU_INTERRUPT_TGT_EXT_0 \
| CPU_INTERRUPT_TGT_EXT_1 \
| CPU_INTERRUPT_TGT_EXT_2 \
| CPU_INTERRUPT_TGT_EXT_3 \
| CPU_INTERRUPT_TGT_EXT_4)
#ifdef CONFIG_USER_ONLY
/*
* Allow some level of source compatibility with softmmu. We do not
* support any of the more exotic features, so only invalid pages may
* be signaled by probe_access_flags().
*/
#define TLB_INVALID_MASK (1 << (TARGET_PAGE_BITS_MIN - 1))
#define TLB_MMIO 0
#define TLB_WATCHPOINT 0
#else
/*
* Flags stored in the low bits of the TLB virtual address.
* These are defined so that fast path ram access is all zeros.
* The flags all must be between TARGET_PAGE_BITS and
* maximum address alignment bit.
*
* Use TARGET_PAGE_BITS_MIN so that these bits are constant
* when TARGET_PAGE_BITS_VARY is in effect.
*/
/* Zero if TLB entry is valid. */
#define TLB_INVALID_MASK (1 << (TARGET_PAGE_BITS_MIN - 1))
/* Set if TLB entry references a clean RAM page. The iotlb entry will
contain the page physical address. */
#define TLB_NOTDIRTY (1 << (TARGET_PAGE_BITS_MIN - 2))
/* Set if TLB entry is an IO callback. */
#define TLB_MMIO (1 << (TARGET_PAGE_BITS_MIN - 3))
/* Set if TLB entry contains a watchpoint. */
#define TLB_WATCHPOINT (1 << (TARGET_PAGE_BITS_MIN - 4))
/* Set if TLB entry requires byte swap. */
#define TLB_BSWAP (1 << (TARGET_PAGE_BITS_MIN - 5))
/* Set if TLB entry writes ignored. */
#define TLB_DISCARD_WRITE (1 << (TARGET_PAGE_BITS_MIN - 6))
/* Use this mask to check interception with an alignment mask
* in a TCG backend.
*/
#define TLB_FLAGS_MASK \
(TLB_INVALID_MASK | TLB_NOTDIRTY | TLB_MMIO \
| TLB_WATCHPOINT | TLB_BSWAP | TLB_DISCARD_WRITE)
/**
* tlb_hit_page: return true if page aligned @addr is a hit against the
* TLB entry @tlb_addr
*
* @addr: virtual address to test (must be page aligned)
* @tlb_addr: TLB entry address (a CPUTLBEntry addr_read/write/code value)
*/
static inline bool tlb_hit_page(target_ulong tlb_addr, target_ulong addr)
{
return addr == (tlb_addr & (TARGET_PAGE_MASK | TLB_INVALID_MASK));
}
/**
* tlb_hit: return true if @addr is a hit against the TLB entry @tlb_addr
*
* @addr: virtual address to test (need not be page aligned)
* @tlb_addr: TLB entry address (a CPUTLBEntry addr_read/write/code value)
*/
static inline bool tlb_hit(target_ulong tlb_addr, target_ulong addr)
{
return tlb_hit_page(tlb_addr, addr & TARGET_PAGE_MASK);
}
void dump_exec_info(void);
void dump_opcount_info(void);
#endif /* !CONFIG_USER_ONLY */
/* Returns: 0 on success, -1 on error */
int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
void *ptr, target_ulong len, bool is_write);
int cpu_exec(CPUState *cpu);
/**
* cpu_set_cpustate_pointers(cpu)
* @cpu: The cpu object
*
* Set the generic pointers in CPUState into the outer object.
*/
static inline void cpu_set_cpustate_pointers(ArchCPU *cpu)
{
cpu->parent_obj.env_ptr = &cpu->env;
cpu->parent_obj.icount_decr_ptr = &cpu->neg.icount_decr;
}
/**
* env_archcpu(env)
* @env: The architecture environment
*
* Return the ArchCPU associated with the environment.
*/
static inline ArchCPU *env_archcpu(CPUArchState *env)
{
return container_of(env, ArchCPU, env);
}
/**
* env_cpu(env)
* @env: The architecture environment
*
* Return the CPUState associated with the environment.
*/
static inline CPUState *env_cpu(CPUArchState *env)
{
return &env_archcpu(env)->parent_obj;
}
/**
* env_neg(env)
* @env: The architecture environment
*
* Return the CPUNegativeOffsetState associated with the environment.
*/
static inline CPUNegativeOffsetState *env_neg(CPUArchState *env)
{
ArchCPU *arch_cpu = container_of(env, ArchCPU, env);
return &arch_cpu->neg;
}
/**
* cpu_neg(cpu)
* @cpu: The generic CPUState
*
* Return the CPUNegativeOffsetState associated with the cpu.
*/
static inline CPUNegativeOffsetState *cpu_neg(CPUState *cpu)
{
ArchCPU *arch_cpu = container_of(cpu, ArchCPU, parent_obj);
return &arch_cpu->neg;
}
/**
* env_tlb(env)
* @env: The architecture environment
*
* Return the CPUTLB state associated with the environment.
*/
static inline CPUTLB *env_tlb(CPUArchState *env)
{
return &env_neg(env)->tlb;
}
#endif /* CPU_ALL_H */
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