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([2602:ae:1541:f901:c23d:b6:6be1:f147]) by smtp.gmail.com with ESMTPSA id jw1-20020a170903278100b0019cd1ee1523sm21670633plb.30.2023.03.28.15.58.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Mar 2023 15:58:17 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= Subject: [PULL 11/15] include/exec: Change reserved_va semantics to last byte Date: Tue, 28 Mar 2023 15:58:02 -0700 Message-Id: <20230328225806.2278728-12-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230328225806.2278728-1-richard.henderson@linaro.org> References: <20230328225806.2278728-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::102e; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: qemu-devel-bounces+patch=linaro.org@nongnu.org Change the semantics to be the last byte of the guest va, rather than the following byte. This avoids some overflow conditions. Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Richard Henderson --- include/exec/cpu-all.h | 11 ++++++++++- linux-user/arm/target_cpu.h | 2 +- bsd-user/main.c | 10 +++------- bsd-user/mmap.c | 4 ++-- linux-user/elfload.c | 14 +++++++------- linux-user/main.c | 27 +++++++++++++-------------- linux-user/mmap.c | 4 ++-- 7 files changed, 38 insertions(+), 34 deletions(-) diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h index 64cb62dc54..090922e4a8 100644 --- a/include/exec/cpu-all.h +++ b/include/exec/cpu-all.h @@ -152,6 +152,15 @@ static inline void tswap64s(uint64_t *s) */ extern uintptr_t guest_base; extern bool have_guest_base; + +/* + * If non-zero, the guest virtual address space is a contiguous subset + * of the host virtual address space, i.e. '-R reserved_va' is in effect + * either from the command-line or by default. The value is the last + * byte of the guest address space e.g. UINT32_MAX. + * + * If zero, the host and guest virtual address spaces are intermingled. + */ extern unsigned long reserved_va; /* @@ -171,7 +180,7 @@ extern unsigned long reserved_va; #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_) +#define GUEST_ADDR_MAX (reserved_va ? : GUEST_ADDR_MAX_) #else diff --git a/linux-user/arm/target_cpu.h b/linux-user/arm/target_cpu.h index 89ba274cfc..f6383a7cd1 100644 --- a/linux-user/arm/target_cpu.h +++ b/linux-user/arm/target_cpu.h @@ -30,7 +30,7 @@ static inline unsigned long arm_max_reserved_va(CPUState *cs) * the high addresses. Restrict linux-user to the * cached write-back RAM in the system map. */ - return 0x80000000ul; + return 0x7ffffffful; } else { /* * We need to be able to map the commpage. diff --git a/bsd-user/main.c b/bsd-user/main.c index 89f225dead..babc3b009b 100644 --- a/bsd-user/main.c +++ b/bsd-user/main.c @@ -68,13 +68,9 @@ bool have_guest_base; # 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) +# define MAX_RESERVED_VA 0xfffffffful # else -# define MAX_RESERVED_VA (1ul << TARGET_VIRT_ADDR_SPACE_BITS) +# define MAX_RESERVED_VA ((1ul << TARGET_VIRT_ADDR_SPACE_BITS) - 1) # endif # else # define MAX_RESERVED_VA 0 @@ -466,7 +462,7 @@ int main(int argc, char **argv) envlist_free(envlist); if (reserved_va) { - mmap_next_start = reserved_va; + mmap_next_start = reserved_va + 1; } { diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c index 696057551a..565b9f97ed 100644 --- a/bsd-user/mmap.c +++ b/bsd-user/mmap.c @@ -234,7 +234,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, size = HOST_PAGE_ALIGN(size) + alignment; end_addr = start + size; if (end_addr > reserved_va) { - end_addr = reserved_va; + end_addr = reserved_va + 1; } addr = end_addr - qemu_host_page_size; @@ -243,7 +243,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, if (looped) { return (abi_ulong)-1; } - end_addr = reserved_va; + end_addr = reserved_va + 1; addr = end_addr - qemu_host_page_size; looped = 1; continue; diff --git a/linux-user/elfload.c b/linux-user/elfload.c index dfae967908..f1370a7a8b 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -208,7 +208,7 @@ static bool init_guest_commpage(void) * has specified -R reserved_va, which would trigger an assert(). */ if (reserved_va != 0 && - TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE >= reserved_va) { + TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE - 1 > reserved_va) { error_report("Cannot allocate vsyscall page"); exit(EXIT_FAILURE); } @@ -2504,7 +2504,7 @@ static void pgb_have_guest_base(const char *image_name, abi_ulong guest_loaddr, if (guest_hiaddr > reserved_va) { error_report("%s: requires more than reserved virtual " "address space (0x%" PRIx64 " > 0x%lx)", - image_name, (uint64_t)guest_hiaddr + 1, reserved_va); + image_name, (uint64_t)guest_hiaddr, reserved_va); exit(EXIT_FAILURE); } } else { @@ -2525,7 +2525,7 @@ static void pgb_have_guest_base(const char *image_name, abi_ulong guest_loaddr, if (reserved_va) { guest_loaddr = (guest_base >= mmap_min_addr ? 0 : mmap_min_addr - guest_base); - guest_hiaddr = reserved_va - 1; + guest_hiaddr = reserved_va; } /* Reserve the address space for the binary, or reserved_va. */ @@ -2755,7 +2755,7 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr, if (guest_hiaddr > reserved_va) { error_report("%s: requires more than reserved virtual " "address space (0x%" PRIx64 " > 0x%lx)", - image_name, (uint64_t)guest_hiaddr + 1, reserved_va); + image_name, (uint64_t)guest_hiaddr, reserved_va); exit(EXIT_FAILURE); } @@ -2768,17 +2768,17 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr, /* Reserve the memory on the host. */ assert(guest_base != 0); test = g2h_untagged(0); - addr = mmap(test, reserved_va, PROT_NONE, flags, -1, 0); + addr = mmap(test, reserved_va + 1, PROT_NONE, flags, -1, 0); if (addr == MAP_FAILED || addr != test) { error_report("Unable to reserve 0x%lx bytes of virtual address " "space at %p (%s) for use as guest address space (check your " "virtual memory ulimit setting, min_mmap_addr or reserve less " - "using -R option)", reserved_va, test, strerror(errno)); + "using -R option)", reserved_va + 1, test, strerror(errno)); exit(EXIT_FAILURE); } qemu_log_mask(CPU_LOG_PAGE, "%s: base @ %p for %lu bytes\n", - __func__, addr, reserved_va); + __func__, addr, reserved_va + 1); } void probe_guest_base(const char *image_name, abi_ulong guest_loaddr, diff --git a/linux-user/main.c b/linux-user/main.c index 39d9bd4d7a..fe03293516 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -109,11 +109,9 @@ static const char *last_log_filename; # 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(CPU) (0xfffffffful & TARGET_PAGE_MASK) +# define MAX_RESERVED_VA(CPU) 0xfffffffful # else -# define MAX_RESERVED_VA(CPU) (1ul << TARGET_VIRT_ADDR_SPACE_BITS) +# define MAX_RESERVED_VA(CPU) ((1ul << TARGET_VIRT_ADDR_SPACE_BITS) - 1) # endif # else # define MAX_RESERVED_VA(CPU) 0 @@ -379,7 +377,9 @@ static void handle_arg_reserved_va(const char *arg) { char *p; int shift = 0; - reserved_va = strtoul(arg, &p, 0); + unsigned long val; + + val = strtoul(arg, &p, 0); switch (*p) { case 'k': case 'K': @@ -393,10 +393,10 @@ static void handle_arg_reserved_va(const char *arg) break; } if (shift) { - unsigned long unshifted = reserved_va; + unsigned long unshifted = val; p++; - reserved_va <<= shift; - if (reserved_va >> shift != unshifted) { + val <<= shift; + if (val >> shift != unshifted) { fprintf(stderr, "Reserved virtual address too big\n"); exit(EXIT_FAILURE); } @@ -405,6 +405,8 @@ static void handle_arg_reserved_va(const char *arg) fprintf(stderr, "Unrecognised -R size suffix '%s'\n", p); exit(EXIT_FAILURE); } + /* The representation is size - 1, with 0 remaining "default". */ + reserved_va = val ? val - 1 : 0; } static void handle_arg_singlestep(const char *arg) @@ -793,7 +795,7 @@ int main(int argc, char **argv, char **envp) */ max_reserved_va = MAX_RESERVED_VA(cpu); if (reserved_va != 0) { - if (reserved_va % qemu_host_page_size) { + if ((reserved_va + 1) % qemu_host_page_size) { char *s = size_to_str(qemu_host_page_size); fprintf(stderr, "Reserved virtual address not aligned mod %s\n", s); g_free(s); @@ -804,11 +806,8 @@ int main(int argc, char **argv, char **envp) exit(EXIT_FAILURE); } } else if (HOST_LONG_BITS == 64 && TARGET_VIRT_ADDR_SPACE_BITS <= 32) { - /* - * reserved_va must be aligned with the host page size - * as it is used with mmap() - */ - reserved_va = max_reserved_va & qemu_host_page_mask; + /* MAX_RESERVED_VA + 1 is a large power of 2, so is aligned. */ + reserved_va = max_reserved_va; } { diff --git a/linux-user/mmap.c b/linux-user/mmap.c index 995146f60d..0aa8ae7356 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -283,7 +283,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, end_addr = start + size; if (start > reserved_va - size) { /* Start at the top of the address space. */ - end_addr = ((reserved_va - size) & -align) + size; + end_addr = ((reserved_va + 1 - size) & -align) + size; looped = true; } @@ -297,7 +297,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, return (abi_ulong)-1; } /* Re-start at the top of the address space. */ - addr = end_addr = ((reserved_va - size) & -align) + size; + addr = end_addr = ((reserved_va + 1 - size) & -align) + size; looped = true; } else { prot = page_get_flags(addr);