From: Matt Redfearn <matt.redfearn@imgtec.com> To: James Hogan <james@albanarts.com>, Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>, <linux-mips@linux-mips.org> Subject: Re: [PATCH 6/9] MIPS: Call relocate_kernel if CONFIG_RELOCATABLE=y Date: Fri, 4 Dec 2015 08:20:05 +0000 [thread overview] Message-ID: <56614CB5.9020002@imgtec.com> (raw) In-Reply-To: <BA73413A-D335-4692-85A4-9330D7ACAC03@albanarts.com> Hi James, On 03/12/15 18:54, James Hogan wrote: > On 3 December 2015 17:46:14 GMT+00:00, Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> wrote: >> On 12/03/2015 05:53 PM, Matt Redfearn wrote: >> >>>>> If CONFIG_RELOCATABLE is enabled, jump to relocate_kernel. >>>>> >>>>> This function will return the entry point of the relocated kernel >> if >>>>> copy/relocate is sucessful or the original entry point if not. The >> stack >>>>> pointer must then be pointed into the new image. >>>>> >>>>> Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com> >>>>> --- >>>>> arch/mips/kernel/head.S | 20 ++++++++++++++++++++ >>>>> 1 file changed, 20 insertions(+) >>>>> >>>>> diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S >>>>> index 4e4cc5b9a771..7dc043349d66 100644 >>>>> --- a/arch/mips/kernel/head.S >>>>> +++ b/arch/mips/kernel/head.S >>>>> @@ -132,7 +132,27 @@ not_found: >>>>> set_saved_sp sp, t0, t1 >>>>> PTR_SUBU sp, 4 * SZREG # init stack pointer >>>>> >>>>> +#ifdef CONFIG_RELOCATABLE >>>>> + /* Copy kernel and apply the relocations */ >>>>> + jal relocate_kernel >>>>> + >>>>> + /* Repoint the sp into the new kernel image */ >>>>> + PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE >>>>> + PTR_ADDU sp, $28 >>>> Can't you account for it in the previous PTR_LI? >>> During relocate_kernel, $28, pointer to the current thread, >> Ah, it's a register! I thought it was an immediate. Nevermind then. :-) > Although, it could still be reduced: > PTR_ADDU sp, gp, _THREAD_SIZE - 32 - PT_SIZE > > Assuming the immediate is in range of signed 16bit. The immediate would be 32552, so in range of signed 16bit, but that would be brittle if either _THREAD_SIZE or PT_SIZE were to change in future.... Thanks, Matt > > Cheers > James > >> [...] >> >> MBR, Sergei >
WARNING: multiple messages have this Message-ID (diff)
From: Matt Redfearn <matt.redfearn@imgtec.com> To: James Hogan <james@albanarts.com>, Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>, linux-mips@linux-mips.org Subject: Re: [PATCH 6/9] MIPS: Call relocate_kernel if CONFIG_RELOCATABLE=y Date: Fri, 4 Dec 2015 08:20:05 +0000 [thread overview] Message-ID: <56614CB5.9020002@imgtec.com> (raw) Message-ID: <20151204082005.UNvGKoUl-CNq3Duaea_dkgJOt5s2tci_w_xdpVu7abw@z> (raw) In-Reply-To: <BA73413A-D335-4692-85A4-9330D7ACAC03@albanarts.com> Hi James, On 03/12/15 18:54, James Hogan wrote: > On 3 December 2015 17:46:14 GMT+00:00, Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> wrote: >> On 12/03/2015 05:53 PM, Matt Redfearn wrote: >> >>>>> If CONFIG_RELOCATABLE is enabled, jump to relocate_kernel. >>>>> >>>>> This function will return the entry point of the relocated kernel >> if >>>>> copy/relocate is sucessful or the original entry point if not. The >> stack >>>>> pointer must then be pointed into the new image. >>>>> >>>>> Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com> >>>>> --- >>>>> arch/mips/kernel/head.S | 20 ++++++++++++++++++++ >>>>> 1 file changed, 20 insertions(+) >>>>> >>>>> diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S >>>>> index 4e4cc5b9a771..7dc043349d66 100644 >>>>> --- a/arch/mips/kernel/head.S >>>>> +++ b/arch/mips/kernel/head.S >>>>> @@ -132,7 +132,27 @@ not_found: >>>>> set_saved_sp sp, t0, t1 >>>>> PTR_SUBU sp, 4 * SZREG # init stack pointer >>>>> >>>>> +#ifdef CONFIG_RELOCATABLE >>>>> + /* Copy kernel and apply the relocations */ >>>>> + jal relocate_kernel >>>>> + >>>>> + /* Repoint the sp into the new kernel image */ >>>>> + PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE >>>>> + PTR_ADDU sp, $28 >>>> Can't you account for it in the previous PTR_LI? >>> During relocate_kernel, $28, pointer to the current thread, >> Ah, it's a register! I thought it was an immediate. Nevermind then. :-) > Although, it could still be reduced: > PTR_ADDU sp, gp, _THREAD_SIZE - 32 - PT_SIZE > > Assuming the immediate is in range of signed 16bit. The immediate would be 32552, so in range of signed 16bit, but that would be brittle if either _THREAD_SIZE or PT_SIZE were to change in future.... Thanks, Matt > > Cheers > James > >> [...] >> >> MBR, Sergei >
next prev parent reply other threads:[~2015-12-04 8:20 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-12-03 10:08 [PATCH 0/9] MIPS Relocatable kernel & KASLR Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 1/9] MIPS: tools: Add relocs tool Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 2/9] MIPS: tools: Build " Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 3/9] MIPS: Reserve space for relocation table Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 4/9] MIPS: Generate relocation table when CONFIG_RELOCATABLE Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 5/9] MIPS: Kernel: Add relocate.c Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 6/9] MIPS: Call relocate_kernel if CONFIG_RELOCATABLE=y Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 14:24 ` Sergei Shtylyov 2015-12-03 14:53 ` Matt Redfearn 2015-12-03 14:53 ` Matt Redfearn 2015-12-03 17:46 ` Sergei Shtylyov 2015-12-03 18:54 ` James Hogan 2015-12-04 8:20 ` Matt Redfearn [this message] 2015-12-04 8:20 ` Matt Redfearn 2015-12-04 15:37 ` Ralf Baechle 2015-12-04 15:45 ` Matt Redfearn 2015-12-04 15:45 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 7/9] MIPS: bootmem: When relocatable, free memory below kernel Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 8/9] MIPS: Add CONFIG_RELOCATABLE Kconfig option Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 10:08 ` [PATCH 9/9] MIPS: Kernel: Implement kASLR using CONFIG_RELOCATABLE Matt Redfearn 2015-12-03 10:08 ` Matt Redfearn 2015-12-03 22:23 ` [PATCH 0/9] MIPS Relocatable kernel & KASLR Joshua Kinard 2015-12-04 8:14 ` Matt Redfearn 2015-12-04 8:14 ` Matt Redfearn 2015-12-04 13:14 ` Joshua Kinard
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