| Message ID | 20190722151804.25467-3-peter.maydell@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | arm: further improve initrd positioning | expand |
Peter Maydell <peter.maydell@linaro.org> writes: > In commit e6b2b20d9735d4ef we made the boot loader code try to avoid > putting the initrd on top of the kernel. However the expression used > to calculate the start of the initrd: > > info->initrd_start = info->loader_start + > MAX(MIN(info->ram_size / 2, 128 * 1024 * 1024), kernel_size); > > incorrectly uses 'kernel_size' as the offset within RAM of the > highest address to avoid. This is incorrect because the kernel > doesn't start at address 0, but slightly higher than that. This > means that we can still incorrectly end up overlaying the initrd on > the kernel in some cases, for example: > > * The kernel's image_size is 0x0a7a8000 > * The kernel was loaded at 0x40080000 > * The end of the kernel is 0x4A828000 > * The DTB was loaded at 0x4a800000 > > To get this right we need to track the actual highest address used > by the kernel and use that rather than kernel_size. We already > set image_low_addr and image_high_addr for ELF images; set them > also for the various other image types we support, and then use > image_high_addr as the lowest allowed address for the initrd. > (We don't use image_low_addr, but we set it for consistency > with the existing code path for ELF files.) > > Fixes: e6b2b20d9735d4ef > Reported-by: Mark Rutland <mark.rutland@arm.com> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > --- > hw/arm/boot.c | 19 +++++++++++++++++-- > 1 file changed, 17 insertions(+), 2 deletions(-) > > diff --git a/hw/arm/boot.c b/hw/arm/boot.c > index b7b31753aca..c2b89b3bb9b 100644 > --- a/hw/arm/boot.c > +++ b/hw/arm/boot.c > @@ -988,7 +988,7 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu, > int is_linux = 0; > uint64_t elf_entry; > /* Addresses of first byte used and first byte not used by the image */ > - uint64_t image_low_addr, image_high_addr; > + uint64_t image_low_addr = 0, image_high_addr = 0; > int elf_machine; > hwaddr entry; > static const ARMInsnFixup *primary_loader; > @@ -1041,17 +1041,29 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu, > uint64_t loadaddr = info->loader_start + KERNEL_NOLOAD_ADDR; > kernel_size = load_uimage_as(info->kernel_filename, &entry, &loadaddr, > &is_linux, NULL, NULL, as); > + if (kernel_size >= 0) { > + image_low_addr = loadaddr; > + image_high_addr = image_low_addr + kernel_size; > + } > } > if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64) && kernel_size < 0) { > kernel_size = load_aarch64_image(info->kernel_filename, > info->loader_start, &entry, as); > is_linux = 1; > + if (kernel_size >= 0) { > + image_low_addr = entry; > + image_high_addr = image_low_addr + kernel_size; > + } > } else if (kernel_size < 0) { > /* 32-bit ARM */ > entry = info->loader_start + KERNEL_LOAD_ADDR; > kernel_size = load_image_targphys_as(info->kernel_filename, entry, > ram_end - KERNEL_LOAD_ADDR, as); > is_linux = 1; > + if (kernel_size >= 0) { > + image_low_addr = entry; > + image_high_addr = image_low_addr + kernel_size; > + } > } > if (kernel_size < 0) { > error_report("could not load kernel '%s'", info->kernel_filename); > @@ -1083,7 +1095,10 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu, > * we might still make a bad choice here. > */ > info->initrd_start = info->loader_start + > - MAX(MIN(info->ram_size / 2, 128 * 1024 * 1024), kernel_size); > + MIN(info->ram_size / 2, 128 * 1024 * 1024); > + if (image_high_addr) { > + info->initrd_start = MAX(info->initrd_start, image_high_addr); > + } > info->initrd_start = TARGET_PAGE_ALIGN(info->initrd_start); > > if (is_linux) { -- Alex Bennée
diff --git a/hw/arm/boot.c b/hw/arm/boot.c index b7b31753aca..c2b89b3bb9b 100644 --- a/hw/arm/boot.c +++ b/hw/arm/boot.c @@ -988,7 +988,7 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu, int is_linux = 0; uint64_t elf_entry; /* Addresses of first byte used and first byte not used by the image */ - uint64_t image_low_addr, image_high_addr; + uint64_t image_low_addr = 0, image_high_addr = 0; int elf_machine; hwaddr entry; static const ARMInsnFixup *primary_loader; @@ -1041,17 +1041,29 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu, uint64_t loadaddr = info->loader_start + KERNEL_NOLOAD_ADDR; kernel_size = load_uimage_as(info->kernel_filename, &entry, &loadaddr, &is_linux, NULL, NULL, as); + if (kernel_size >= 0) { + image_low_addr = loadaddr; + image_high_addr = image_low_addr + kernel_size; + } } if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64) && kernel_size < 0) { kernel_size = load_aarch64_image(info->kernel_filename, info->loader_start, &entry, as); is_linux = 1; + if (kernel_size >= 0) { + image_low_addr = entry; + image_high_addr = image_low_addr + kernel_size; + } } else if (kernel_size < 0) { /* 32-bit ARM */ entry = info->loader_start + KERNEL_LOAD_ADDR; kernel_size = load_image_targphys_as(info->kernel_filename, entry, ram_end - KERNEL_LOAD_ADDR, as); is_linux = 1; + if (kernel_size >= 0) { + image_low_addr = entry; + image_high_addr = image_low_addr + kernel_size; + } } if (kernel_size < 0) { error_report("could not load kernel '%s'", info->kernel_filename); @@ -1083,7 +1095,10 @@ static void arm_setup_direct_kernel_boot(ARMCPU *cpu, * we might still make a bad choice here. */ info->initrd_start = info->loader_start + - MAX(MIN(info->ram_size / 2, 128 * 1024 * 1024), kernel_size); + MIN(info->ram_size / 2, 128 * 1024 * 1024); + if (image_high_addr) { + info->initrd_start = MAX(info->initrd_start, image_high_addr); + } info->initrd_start = TARGET_PAGE_ALIGN(info->initrd_start); if (is_linux) {
In commit e6b2b20d9735d4ef we made the boot loader code try to avoid putting the initrd on top of the kernel. However the expression used to calculate the start of the initrd: info->initrd_start = info->loader_start + MAX(MIN(info->ram_size / 2, 128 * 1024 * 1024), kernel_size); incorrectly uses 'kernel_size' as the offset within RAM of the highest address to avoid. This is incorrect because the kernel doesn't start at address 0, but slightly higher than that. This means that we can still incorrectly end up overlaying the initrd on the kernel in some cases, for example: * The kernel's image_size is 0x0a7a8000 * The kernel was loaded at 0x40080000 * The end of the kernel is 0x4A828000 * The DTB was loaded at 0x4a800000 To get this right we need to track the actual highest address used by the kernel and use that rather than kernel_size. We already set image_low_addr and image_high_addr for ELF images; set them also for the various other image types we support, and then use image_high_addr as the lowest allowed address for the initrd. (We don't use image_low_addr, but we set it for consistency with the existing code path for ELF files.) Fixes: e6b2b20d9735d4ef Reported-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- hw/arm/boot.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) -- 2.20.1