From 7ef295ea5b412cbaf82f719ccd49efb51296e841 Mon Sep 17 00:00:00 2001 From: Peter Crosthwaite Date: Fri, 4 Mar 2016 11:30:21 +0000 Subject: loader: Add data swap option to load-elf Some CPUs are of an opposite data-endianness to other components in the system. Sometimes elfs have the data sections layed out with this CPU data-endianness accounting for when loaded via the CPU, so byte swaps (relative to other system components) will occur. The leading example, is ARM's BE32 mode, which is is basically LE with address manipulation on half-word and byte accesses to access the hw/byte reversed address. This means that word data is invariant across LE and BE32. This also means that instructions are still LE. The expectation is that the elf will be loaded via the CPU in this endianness scheme, which means the data in the elf is reversed at compile time. As QEMU loads via the system memory directly, rather than the CPU, we need a mechanism to reverse elf data endianness to implement this possibility. Reviewed-by: Peter Maydell Signed-off-by: Peter Crosthwaite Signed-off-by: Peter Maydell --- hw/arm/boot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'hw/arm/boot.c') diff --git a/hw/arm/boot.c b/hw/arm/boot.c index 0a56d34cfe..17400beb58 100644 --- a/hw/arm/boot.c +++ b/hw/arm/boot.c @@ -755,7 +755,7 @@ static void arm_load_kernel_notify(Notifier *notifier, void *data) /* Assume that raw images are linux kernels, and ELF images are not. */ kernel_size = load_elf(info->kernel_filename, NULL, NULL, &elf_entry, &elf_low_addr, &elf_high_addr, big_endian, - elf_machine, 1); + elf_machine, 1, 0); if (kernel_size > 0 && have_dtb(info)) { /* If there is still some room left at the base of RAM, try and put * the DTB there like we do for images loaded with -bios or -pflash. -- cgit 1.4.1 From 9776f636455b6f0d9c14dce112242ed653f954b4 Mon Sep 17 00:00:00 2001 From: Peter Crosthwaite Date: Fri, 4 Mar 2016 11:30:21 +0000 Subject: arm: boot: Support big-endian elfs Support ARM big-endian ELF files in system-mode emulation. When loading an elf, determine the endianness mode expected by the elf, and set the relevant CPU state accordingly. With this, big-endian modes are now fully supported via system-mode LE, so there is no need to restrict the elf loading to the TARGET endianness so the ifdeffery on TARGET_WORDS_BIGENDIAN goes away. Signed-off-by: Peter Crosthwaite Reviewed-by: Peter Maydell [PMM: fix typo in comments] Signed-off-by: Peter Maydell --- hw/arm/boot.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++------ include/hw/arm/arm.h | 9 +++++ 2 files changed, 92 insertions(+), 10 deletions(-) (limited to 'hw/arm/boot.c') diff --git a/hw/arm/boot.c b/hw/arm/boot.c index 17400beb58..8ba0e4272a 100644 --- a/hw/arm/boot.c +++ b/hw/arm/boot.c @@ -518,9 +518,34 @@ static void do_cpu_reset(void *opaque) cpu_reset(cs); if (info) { if (!info->is_linux) { + int i; /* Jump to the entry point. */ uint64_t entry = info->entry; + switch (info->endianness) { + case ARM_ENDIANNESS_LE: + env->cp15.sctlr_el[1] &= ~SCTLR_E0E; + for (i = 1; i < 4; ++i) { + env->cp15.sctlr_el[i] &= ~SCTLR_EE; + } + env->uncached_cpsr &= ~CPSR_E; + break; + case ARM_ENDIANNESS_BE8: + env->cp15.sctlr_el[1] |= SCTLR_E0E; + for (i = 1; i < 4; ++i) { + env->cp15.sctlr_el[i] |= SCTLR_EE; + } + env->uncached_cpsr |= CPSR_E; + break; + case ARM_ENDIANNESS_BE32: + env->cp15.sctlr_el[1] |= SCTLR_B; + break; + case ARM_ENDIANNESS_UNKNOWN: + break; /* Board's decision */ + default: + g_assert_not_reached(); + } + if (!env->aarch64) { env->thumb = info->entry & 1; entry &= 0xfffffffe; @@ -638,6 +663,62 @@ static int do_arm_linux_init(Object *obj, void *opaque) return 0; } +static uint64_t arm_load_elf(struct arm_boot_info *info, uint64_t *pentry, + uint64_t *lowaddr, uint64_t *highaddr, + int elf_machine) +{ + bool elf_is64; + union { + Elf32_Ehdr h32; + Elf64_Ehdr h64; + } elf_header; + int data_swab = 0; + bool big_endian; + uint64_t ret = -1; + Error *err = NULL; + + + load_elf_hdr(info->kernel_filename, &elf_header, &elf_is64, &err); + if (err) { + return ret; + } + + if (elf_is64) { + big_endian = elf_header.h64.e_ident[EI_DATA] == ELFDATA2MSB; + info->endianness = big_endian ? ARM_ENDIANNESS_BE8 + : ARM_ENDIANNESS_LE; + } else { + big_endian = elf_header.h32.e_ident[EI_DATA] == ELFDATA2MSB; + if (big_endian) { + if (bswap32(elf_header.h32.e_flags) & EF_ARM_BE8) { + info->endianness = ARM_ENDIANNESS_BE8; + } else { + info->endianness = ARM_ENDIANNESS_BE32; + /* In BE32, the CPU has a different view of the per-byte + * address map than the rest of the system. BE32 ELF files + * are organised such that they can be programmed through + * the CPU's per-word byte-reversed view of the world. QEMU + * however loads ELF files independently of the CPU. So + * tell the ELF loader to byte reverse the data for us. + */ + data_swab = 2; + } + } else { + info->endianness = ARM_ENDIANNESS_LE; + } + } + + ret = load_elf(info->kernel_filename, NULL, NULL, + pentry, lowaddr, highaddr, big_endian, elf_machine, + 1, data_swab); + if (ret <= 0) { + /* The header loaded but the image didn't */ + exit(1); + } + + return ret; +} + static void arm_load_kernel_notify(Notifier *notifier, void *data) { CPUState *cs; @@ -647,7 +728,6 @@ static void arm_load_kernel_notify(Notifier *notifier, void *data) uint64_t elf_entry, elf_low_addr, elf_high_addr; int elf_machine; hwaddr entry, kernel_load_offset; - int big_endian; static const ARMInsnFixup *primary_loader; ArmLoadKernelNotifier *n = DO_UPCAST(ArmLoadKernelNotifier, notifier, notifier); @@ -733,12 +813,6 @@ static void arm_load_kernel_notify(Notifier *notifier, void *data) if (info->nb_cpus == 0) info->nb_cpus = 1; -#ifdef TARGET_WORDS_BIGENDIAN - big_endian = 1; -#else - big_endian = 0; -#endif - /* We want to put the initrd far enough into RAM that when the * kernel is uncompressed it will not clobber the initrd. However * on boards without much RAM we must ensure that we still leave @@ -753,9 +827,8 @@ static void arm_load_kernel_notify(Notifier *notifier, void *data) MIN(info->ram_size / 2, 128 * 1024 * 1024); /* Assume that raw images are linux kernels, and ELF images are not. */ - kernel_size = load_elf(info->kernel_filename, NULL, NULL, &elf_entry, - &elf_low_addr, &elf_high_addr, big_endian, - elf_machine, 1, 0); + kernel_size = arm_load_elf(info, &elf_entry, &elf_low_addr, + &elf_high_addr, elf_machine); if (kernel_size > 0 && have_dtb(info)) { /* If there is still some room left at the base of RAM, try and put * the DTB there like we do for images loaded with -bios or -pflash. diff --git a/include/hw/arm/arm.h b/include/hw/arm/arm.h index 52ecf4aa8f..b2517f9a43 100644 --- a/include/hw/arm/arm.h +++ b/include/hw/arm/arm.h @@ -16,6 +16,13 @@ #include "qemu/notify.h" #include "cpu.h" +typedef enum { + ARM_ENDIANNESS_UNKNOWN = 0, + ARM_ENDIANNESS_LE, + ARM_ENDIANNESS_BE8, + ARM_ENDIANNESS_BE32, +} arm_endianness; + /* armv7m.c */ DeviceState *armv7m_init(MemoryRegion *system_memory, int mem_size, int num_irq, const char *kernel_filename, const char *cpu_model); @@ -103,6 +110,8 @@ struct arm_boot_info { * changing to non-secure state if implementing a non-secure boot */ bool secure_board_setup; + + arm_endianness endianness; }; /** -- cgit 1.4.1