From: Matt Redfearn <matt.redfearn@imgtec.com> To: 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: Thu, 3 Dec 2015 14:53:51 +0000 [thread overview] Message-ID: <5660577F.2020401@imgtec.com> (raw) In-Reply-To: <56605081.5050307@cogentembedded.com> Hi Sergei, On 03/12/15 14:24, Sergei Shtylyov wrote: > Hello. > > On 12/3/2015 1:08 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, has been moved by an unknown (here) number of bytes to point to the init_thread_union within the new kernel. The stack pointer must now be pointed there too. Since we don't know the offset from the original kernel it's easier to simply recalculate it. Thanks, Matt > >> + set_saved_sp sp, t0, t1 >> + PTR_SUBU sp, 4 * SZREG # init stack pointer > [...] > > MBR, Sergei >
WARNING: multiple messages have this Message-ID (diff)
From: Matt Redfearn <matt.redfearn@imgtec.com> To: 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: Thu, 3 Dec 2015 14:53:51 +0000 [thread overview] Message-ID: <5660577F.2020401@imgtec.com> (raw) Message-ID: <20151203145351.Hr15lIscXiCFPGz02GJgQ29WEQrkQtKZ6GPQmsgy3nI@z> (raw) In-Reply-To: <56605081.5050307@cogentembedded.com> Hi Sergei, On 03/12/15 14:24, Sergei Shtylyov wrote: > Hello. > > On 12/3/2015 1:08 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, has been moved by an unknown (here) number of bytes to point to the init_thread_union within the new kernel. The stack pointer must now be pointed there too. Since we don't know the offset from the original kernel it's easier to simply recalculate it. Thanks, Matt > >> + set_saved_sp sp, t0, t1 >> + PTR_SUBU sp, 4 * SZREG # init stack pointer > [...] > > MBR, Sergei >
next prev parent reply other threads:[~2015-12-03 14:54 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 [this message] 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 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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