[PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr

["Suzuki K. Poulose" <suzuki@in.ibm.com>]

From: Suzuki K. Poulose <suzuki@in.ibm.com>

uImage probe fills the entry point (ep) based on the load_addr
from the uImage headers. If we change the load_addr, we should
accordingly update the entry point.

For ELF, calculate the offset of e_entry from the virtual start
address and add it to the physical start address to find the
physical address of kernel entry.

i.e,
  pa (e_entry) = pa(phdr[0].p_vaddr) + (e_entry - phdr[0].p_vaddr)
               = kernel_addr + (e_entry - phdr[0].p_vaddr)

Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Matthew McClintock <msm@freescale.com>
---
 kexec/arch/ppc/kexec-elf-ppc.c    |   12 ++++++++----
 kexec/arch/ppc/kexec-uImage-ppc.c |    6 +++++-
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/kexec/arch/ppc/kexec-elf-ppc.c b/kexec/arch/ppc/kexec-elf-ppc.c
index 8e408cc..5f63a64 100644
--- a/kexec/arch/ppc/kexec-elf-ppc.c
+++ b/kexec/arch/ppc/kexec-elf-ppc.c
@@ -397,10 +397,14 @@ int elf_ppc_load(int argc, char **argv,	const char *buf, off_t len,
 		die("Error device tree not loadded to address it was expecting to be loaded too!\n");
 	}
 
-	/* set various variables for the purgatory  ehdr.e_entry is a
-	 * virtual address, we can use kernel_addr which
-	 * should be the physical start address of the kernel */
-	addr = kernel_addr;
+	/* 
+	 * set various variables for the purgatory.
+	 * ehdr.e_entry is a virtual address. we know physical start
+	 * address of the kernel (kernel_addr). Find the offset of
+	 * e_entry from the virtual start address(e_phdr[0].p_vaddr)
+	 * and calculate the actual physical address of the 'kernel entry'.
+	 */
+	addr = kernel_addr + (ehdr.e_entry - ehdr.e_phdr[0].p_vaddr);
 	elf_rel_set_symbol(&info->rhdr, "kernel", &addr, sizeof(addr));
 
 	addr = dtb_addr;
diff --git a/kexec/arch/ppc/kexec-uImage-ppc.c b/kexec/arch/ppc/kexec-uImage-ppc.c
index e0bc7bb..900cd16 100644
--- a/kexec/arch/ppc/kexec-uImage-ppc.c
+++ b/kexec/arch/ppc/kexec-uImage-ppc.c
@@ -159,15 +159,19 @@ static int ppc_load_bare_bits(int argc, char **argv, const char *buf,
 
 	/*
 	 * If the provided load_addr cannot be allocated, find a new
-	 * area.
+	 * area. Rebase the entry point based on the new load_addr.
 	 */
 	if (!valid_memory_range(info, load_addr, load_addr + (len + _1MiB))) {
+		int ep_offset = ep - load_addr;
+
 		load_addr = locate_hole(info, len + _1MiB, 0, 0, max_addr, 1);
 		if (load_addr == ULONG_MAX) {
 			printf("Can't allocate memory for kernel of len %ld\n",
 					len + _1MiB);
 			return -1;
 		}
+
+		ep = load_addr + ep_offset;
 	}
 
 	add_segment(info, buf, len, load_addr, len + _1MiB);


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