From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Fri, 22 Oct 2021 09:53:15 +1100 Subject: [PATCH] powerpc-ieee1275: load grub at 4MB, not 2MB This was first reported under PFW but reproduces under SLOF. - The core.elf was 2126152 = 0x207148 bytes in size with the following program headers (per readelf): Entry point 0x200000 There are 4 program headers, starting at offset 52 Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align LOAD 0x000160 0x00200000 0x00200000 0x21f98 0x2971c RWE 0x8 GNU_STACK 0x0220f8 0x00000000 0x00000000 0x00000 0x00000 RWE 0x4 LOAD 0x0220f8 0x00232000 0x00232000 0x1e4e50 0x1e4e50 RWE 0x4 NOTE 0x206f48 0x00000000 0x00000000 0x00200 0x00000 R 0x4 - SLOF places the ELF file at 0x4000 (after the reserved space for interrupt handlers etc.) upwards. The image was 2126152 = 0x207148 bytes in size, so it runs from 0x4000 - 0x20b148. We'll call 0x4000 the load address. 0x0 0x4000 0x20b148 |----------|--------------| | reserved | ELF contents | - SLOF then copies the first LOAD program header (for .text). That runs for 0x21f98 bytes. It runs from (load addr + 0x160) to (load addr + 0x160 + 0x21f98) = 0x4160 to 0x260f8 and we copy it to 0x200000 to 0x221f98. This overwrites the end of the image: 0x0 0x4000 0x200000 0x221f98 |----------|------------|---------------| | reserved | ELF cont.. | .text section | - SLOF zeros the bss up to PhysAddr + MemSize = 0x22971c 0x0 0x4000 0x200000 0x221f98 0x22971c |----------|------------|---------------|--------| | reserved | ELF cont.. | .text section | bss 0s | - SLOF then goes to fulfil the next LOAD header (for mods), which is for 0x1e4e50 bytes. We copy from (load addr + 0x220f8) to (load addr + 0x220f8 + 0x1e4e50) = 0x260f8 to 0x20af48 and we copy it to 0x232000 to 0x416e50: 0x0 0x4000 0x200000 0x221f98 0x22971c |----------|------------|---------------|--------| | reserved | ELF cont.. | .text section | bss 0s | |-------------| | copied area | 0x260f8 0x20af48 This goes poorly: 0x0 0x4000 0x200000 0x221f98 0x22971c 0x232000 0x40bf08 0x416e50 |----------|------------|---------------|--------|-----|-----------|-------------| | reserved | ELF cont.. | .text section | bss 0s | pad | some mods | .text start | This matches the observations on the running system - 0x40bf08 was where the contents of memory no longer matched the contents of the ELF file. This was reported as a license verification failure on SLOF as the last module's .module_license section fell past where the corruption began. Signed-off-by: Daniel Axtens [rharwood@redhat.com: trim very detailed commit message] Signed-off-by: Robbie Harwood --- grub-core/Makefile.core.def | 2 +- include/grub/offsets.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def index 4a57de975e..08ac0fb15f 100644 --- a/grub-core/Makefile.core.def +++ b/grub-core/Makefile.core.def @@ -89,7 +89,7 @@ kernel = { i386_xen_pvh_ldflags = '$(TARGET_IMG_BASE_LDOPT),0x100000'; mips_loongson_ldflags = '-Wl,-Ttext,0x80200000'; - powerpc_ieee1275_ldflags = '-Wl,-Ttext,0x200000'; + powerpc_ieee1275_ldflags = '-Wl,-Ttext,0x400000'; sparc64_ieee1275_ldflags = '-Wl,-Ttext,0x4400'; mips_arc_ldflags = '-Wl,-Ttext,$(TARGET_LINK_ADDR)'; mips_qemu_mips_ldflags = '-Wl,-Ttext,0x80200000'; diff --git a/include/grub/offsets.h b/include/grub/offsets.h index 871e1cd4c3..69211aa798 100644 --- a/include/grub/offsets.h +++ b/include/grub/offsets.h @@ -63,7 +63,7 @@ #define GRUB_KERNEL_SPARC64_IEEE1275_LINK_ADDR 0x4400 #define GRUB_KERNEL_POWERPC_IEEE1275_LINK_ALIGN 4 -#define GRUB_KERNEL_POWERPC_IEEE1275_LINK_ADDR 0x200000 +#define GRUB_KERNEL_POWERPC_IEEE1275_LINK_ADDR 0x400000 #define GRUB_KERNEL_MIPS_LOONGSON_LINK_ADDR 0x80200000