* Re: [PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr [not found] <20130303073540.12040.16854.stgit@suzukikp> @ 2013-03-04 1:41 ` Simon Horman 2013-03-04 5:56 ` Suzuki K. Poulose 0 siblings, 1 reply; 3+ messages in thread From: Simon Horman @ 2013-03-04 1:41 UTC (permalink / raw) To: Suzuki K. Poulose Cc: Matthew McClintock, Sebastian Andrzej Siewior, kexec, linuxppc-dev [ Cc: linuxppc-dev@lists.ozlabs.org ] On Sun, Mar 03, 2013 at 01:06:00PM +0530, Suzuki K. Poulose wrote: > 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) Would it be possible for someone to provide a review of this change? > > 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); > > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr 2013-03-04 1:41 ` [PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr Simon Horman @ 2013-03-04 5:56 ` Suzuki K. Poulose 2013-03-05 1:40 ` Simon Horman 0 siblings, 1 reply; 3+ messages in thread From: Suzuki K. Poulose @ 2013-03-04 5:56 UTC (permalink / raw) To: Simon Horman Cc: Matthew McClintock, Sebastian Andrzej Siewior, kexec, linuxppc-dev On 03/04/2013 07:11 AM, Simon Horman wrote: > [ Cc: linuxppc-dev@lists.ozlabs.org ] > > On Sun, Mar 03, 2013 at 01:06:00PM +0530, Suzuki K. Poulose wrote: >> 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) > > Would it be possible for someone to provide a review of this change? To make it bit more clear : The entry point of the kernel is usually at 0 offset from the first PT_LOAD section. The current code makes this assumption and uses the pa(phdr[0].p_vaddr) as the kernel entry. But this *may* not be true always, in such a case the kexec would fail. While I fixed the uImage case, I thought it would be better to handle the same case in ELF. Btw, this calculation is not specific to ppc32. Thanks Suzuki > >> >> 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); >> >> >> _______________________________________________ >> kexec mailing list >> kexec@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/kexec >> > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr 2013-03-04 5:56 ` Suzuki K. Poulose @ 2013-03-05 1:40 ` Simon Horman 0 siblings, 0 replies; 3+ messages in thread From: Simon Horman @ 2013-03-05 1:40 UTC (permalink / raw) To: Suzuki K. Poulose Cc: Matthew McClintock, Sebastian Andrzej Siewior, kexec, linuxppc-dev On Mon, Mar 04, 2013 at 11:26:24AM +0530, Suzuki K. Poulose wrote: > On 03/04/2013 07:11 AM, Simon Horman wrote: > >[ Cc: linuxppc-dev@lists.ozlabs.org ] > > > >On Sun, Mar 03, 2013 at 01:06:00PM +0530, Suzuki K. Poulose wrote: > >>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) > > > >Would it be possible for someone to provide a review of this change? > To make it bit more clear : > > The entry point of the kernel is usually at 0 offset from the first > PT_LOAD section. The current code makes this assumption and uses the > pa(phdr[0].p_vaddr) as the kernel entry. > > But this *may* not be true always, in such a case the kexec would fail. > While I fixed the uImage case, I thought it would be better to > handle the same case in ELF. > > Btw, this calculation is not specific to ppc32. Thanks, I have applied the patch. ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-03-05 1:40 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
[not found] <20130303073540.12040.16854.stgit@suzukikp>
2013-03-04 1:41 ` [PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr Simon Horman
2013-03-04 5:56 ` Suzuki K. Poulose
2013-03-05 1:40 ` Simon Horman
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).