Re: [PATCH v3 3/6] powerpc/fsl_booke/64: implement KASLR for fsl_booke64

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





在 2020/2/26 10:40, Jason Yan 写道:


在 2020/2/20 21:48, Christophe Leroy 写道:


Le 06/02/2020 à 03:58, Jason Yan a écrit :
The implementation for Freescale BookE64 is similar as BookE32. One
difference is that Freescale BookE64 set up a TLB mapping of 1G during
booting. Another difference is that ppc64 needs the kernel to be
64K-aligned. So we can randomize the kernel in this 1G mapping and make
it 64K-aligned. This can save some code to creat another TLB map at
early boot. The disadvantage is that we only have about 1G/64K = 16384
slots to put the kernel in.

To support secondary cpu boot up, a variable __kaslr_offset was added in
first_256B section. This can help secondary cpu get the kaslr offset
before the 1:1 mapping has been setup.

Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx>
Cc: Scott Wood <oss@xxxxxxxxxxxx>
Cc: Diana Craciun <diana.craciun@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
---
  arch/powerpc/Kconfig                 |  2 +-
  arch/powerpc/kernel/exceptions-64e.S | 10 +++++++++
  arch/powerpc/kernel/head_64.S        |  7 ++++++
  arch/powerpc/kernel/setup_64.c       |  4 +++-
  arch/powerpc/mm/mmu_decl.h           | 16 +++++++-------
  arch/powerpc/mm/nohash/kaslr_booke.c | 33 +++++++++++++++++++++++++---
  6 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c150a9d49343..754aeb96bb1c 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -568,7 +568,7 @@ config RELOCATABLE
  config RANDOMIZE_BASE
      bool "Randomize the address of the kernel image"
-    depends on (FSL_BOOKE && FLATMEM && PPC32)
+    depends on (PPC_FSL_BOOK3E && FLATMEM)
      depends on RELOCATABLE
      help
        Randomizes the virtual address at which the kernel image is
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 1b9b174bee86..c1c05b8684ca 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -1378,6 +1378,7 @@ skpinv:    addi    r6,r6,1                /* Increment */
  1:    mflr    r6
      addi    r6,r6,(2f - 1b)
      tovirt(r6,r6)
+    add    r6,r6,r19
      lis    r7,MSR_KERNEL@h
      ori    r7,r7,MSR_KERNEL@l
      mtspr    SPRN_SRR0,r6
@@ -1400,6 +1401,7 @@ skpinv:    addi    r6,r6,1                /* Increment */
      /* We translate LR and return */
      tovirt(r8,r8)
+    add    r8,r8,r19
      mtlr    r8
      blr
@@ -1528,6 +1530,7 @@ a2_tlbinit_code_end:
   */
  _GLOBAL(start_initialization_book3e)
      mflr    r28
+    li    r19, 0
      /* First, we need to setup some initial TLBs to map the kernel
       * text, data and bss at PAGE_OFFSET. We don't have a real mode
@@ -1570,6 +1573,12 @@ _GLOBAL(book3e_secondary_core_init)
      cmplwi    r4,0
      bne    2f
+    li    r19, 0
+#ifdef CONFIG_RANDOMIZE_BASE
+    LOAD_REG_ADDR_PIC(r19, __kaslr_offset)
+    lwz    r19,0(r19)
+    rlwinm  r19,r19,0,0,5
+#endif
      /* Setup TLB for this core */
      bl    initial_tlb_book3e
@@ -1602,6 +1611,7 @@ _GLOBAL(book3e_secondary_core_init)
      lis    r3,PAGE_OFFSET@highest
      sldi    r3,r3,32
      or    r28,r28,r3
+    add    r28,r28,r19
  1:    mtlr    r28
      blr
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index ad79fddb974d..744624140fb8 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -104,6 +104,13 @@ __secondary_hold_acknowledge:
      .8byte    0x0
  #ifdef CONFIG_RELOCATABLE
+#ifdef CONFIG_RANDOMIZE_BASE
+    . = 0x58
+    .globl    __kaslr_offset
+__kaslr_offset:
+DEFINE_FIXED_SYMBOL(__kaslr_offset)
+    .long    0
+#endif
      /* This flag is set to 1 by a loader if the kernel should run
       * at the loaded address instead of the linked address.  This
       * is used by kexec-tools to keep the the kdump kernel in the
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 6104917a282d..a16b970a8d1a 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -66,7 +66,7 @@
  #include <asm/feature-fixups.h>
  #include <asm/kup.h>
  #include <asm/early_ioremap.h>
-

Why remove this new line which clearly separates things in asm/ and things in local dir ?

Sorry to break this. I will add the new line back.


+#include <mm/mmu_decl.h>
  #include "setup.h"
  int spinning_secondaries;
@@ -300,6 +300,8 @@ void __init early_setup(unsigned long dt_ptr)
      /* Enable early debugging if any specified (see udbg.h) */
      udbg_early_init();
+    kaslr_early_init(__va(dt_ptr), 0);
+
      udbg_printf(" -> %s(), dt_ptr: 0x%lx\n", __func__, dt_ptr);
      /*
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 3e1c85c7d10b..bbd721d1e3d7 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -147,14 +147,6 @@ void reloc_kernel_entry(void *fdt, long addr);
  extern void loadcam_entry(unsigned int index);
  extern void loadcam_multi(int first_idx, int num, int tmp_idx);
-#ifdef CONFIG_RANDOMIZE_BASE
-void kaslr_early_init(void *dt_ptr, phys_addr_t size);
-void kaslr_late_init(void);
-#else
-static inline void kaslr_early_init(void *dt_ptr, phys_addr_t size) {}
-static inline void kaslr_late_init(void) {}
-#endif
-
  struct tlbcam {
      u32    MAS0;
      u32    MAS1;
@@ -164,6 +156,14 @@ struct tlbcam {
  };
  #endif
+#ifdef CONFIG_RANDOMIZE_BASE
+void kaslr_early_init(void *dt_ptr, phys_addr_t size);
+void kaslr_late_init(void);
+#else
+static inline void kaslr_early_init(void *dt_ptr, phys_addr_t size) {}
+static inline void kaslr_late_init(void) {}
+#endif
+
  #if defined(CONFIG_PPC_BOOK3S_32) || defined(CONFIG_FSL_BOOKE) || defined(CONFIG_PPC_8xx)
  /* 6xx have BATS */
  /* FSL_BOOKE have TLBCAM */
diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
index 07b036e98353..c6f5c1db1394 100644
--- a/arch/powerpc/mm/nohash/kaslr_booke.c
+++ b/arch/powerpc/mm/nohash/kaslr_booke.c
@@ -231,7 +231,7 @@ static __init unsigned long get_usable_address(const void *fdt,
      unsigned long pa;
      unsigned long pa_end;
-    for (pa = offset; (long)pa > (long)start; pa -= SZ_16K) {
+    for (pa = offset; (long)pa > (long)start; pa -= SZ_64K) {

Doesn't this modify the behaviour for PPC32 too ?

Oh, yes. I will fix this.


          pa_end = pa + regions.kernel_size;
          if (overlaps_region(fdt, pa, pa_end))
              continue;
@@ -265,14 +265,14 @@ static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned long rando
  {
      unsigned long koffset = 0;
      unsigned long start;
-    unsigned long index;
      unsigned long offset;
+#ifdef CONFIG_PPC32

Can we use

if (IS_ENABLED(CONFIG_PPC32)) {
     /* 32 bits stuff */
} else {
     /* 64 bits stuff */
}

Thansk for the suggestion. I will consider to use IS_ENABLED() instead.


      /*
       * Decide which 64M we want to start
       * Only use the low 8 bits of the random seed
       */
-    index = random & 0xFF;
+    unsigned long index = random & 0xFF;

That's not good in terms of readability, index declaration should remain at the top of the function, should be possible if using IS_ENABLED() instead

I'm wondering how to declare a variable inside a code block such as if (IS_ENABLED(CONFIG_PPC32)) at the top of the function and use the variable in another if (IS_ENABLED(CONFIG_PPC32)). Is there any good idea?


Hi Christophe,

When using a standard C if/else, all code compiled for PPC32 and PPC64, but this will bring some build error because not all variables both defined for PPC32 and PPC64.

[yanaijie@138 linux]$ sh ppc64build.sh
  CALL    scripts/atomic/check-atomics.sh
  CALL    scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  CC      arch/powerpc/mm/nohash/kaslr_booke.o
arch/powerpc/mm/nohash/kaslr_booke.c: In function 'kaslr_choose_location':
arch/powerpc/mm/nohash/kaslr_booke.c:341:30: error: 'CONFIG_LOWMEM_CAM_NUM' undeclared (first use in this function); did you mean 'CONFIG_FLATMEM_MANUAL'?
   ram = map_mem_in_cams(ram, CONFIG_LOWMEM_CAM_NUM, true);
                              ^~~~~~~~~~~~~~~~~~~~~
                              CONFIG_FLATMEM_MANUAL
arch/powerpc/mm/nohash/kaslr_booke.c:341:30: note: each undeclared identifier is reported only once for each function it appears in
arch/powerpc/mm/nohash/kaslr_booke.c: In function 'kaslr_early_init':
arch/powerpc/mm/nohash/kaslr_booke.c:404:3: error: 'is_second_reloc' undeclared (first use in this function); did you mean '__cond_lock'?
   is_second_reloc = 1;
   ^~~~~~~~~~~~~~~
   __cond_lock
arch/powerpc/mm/nohash/kaslr_booke.c:411:4: error: implicit declaration of function 'create_kaslr_tlb_entry'; did you mean 'reloc_kernel_entry'? [-Werror=implicit-function-declaration]
    create_kaslr_tlb_entry(1, tlb_virt, tlb_phys);
    ^~~~~~~~~~~~~~~~~~~~~~
    reloc_kernel_entry
cc1: all warnings being treated as errors
make[3]: *** [scripts/Makefile.build:268: arch/powerpc/mm/nohash/kaslr_booke.o] Error 1
make[2]: *** [scripts/Makefile.build:505: arch/powerpc/mm/nohash] Error 2
make[1]: *** [scripts/Makefile.build:505: arch/powerpc/mm] Error 2
make: *** [Makefile:1681: arch/powerpc] Error 2

Thanks,
Jason


      index %= regions.linear_sz / SZ_64M;
      /* Decide offset inside 64M */
@@ -287,6 +287,15 @@ static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned long rando
              break;
          index--;
      }
+#else
+    /* Decide kernel offset inside 1G */
+    offset = random % (SZ_1G - regions.kernel_size);
+    offset = round_down(offset, SZ_64K);
+
+    start = memstart_addr;
+    offset = memstart_addr + offset;
+    koffset = get_usable_address(dt_ptr, start, offset);
+#endif
      if (koffset != 0)
          koffset -= memstart_addr;
@@ -325,6 +334,7 @@ static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size
      else
          pr_warn("KASLR: No safe seed for randomizing the kernel base.\n");
+#ifdef CONFIG_PPC32
      ram = min_t(phys_addr_t, __max_low_memory, size);
      ram = map_mem_in_cams(ram, CONFIG_LOWMEM_CAM_NUM, true);
      linear_sz = min_t(unsigned long, ram, SZ_512M);
@@ -332,6 +342,7 @@ static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size
      /* If the linear size is smaller than 64M, do not randmize */
      if (linear_sz < SZ_64M)
          return 0;
+#endif
      /* check for a reserved-memory node and record its cell sizes */
      regions.reserved_mem = fdt_path_offset(dt_ptr, "/reserved-memory"); @@ -363,6 +374,17 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
      unsigned long offset;
      unsigned long kernel_sz;
+#ifdef CONFIG_PPC64

Same, can we use a standard C if/else sequence with IS_ENABLED(CONFIG_PPC64) ?

OK, I will try to do this if I can deal with the declaration of variables in different if/else sequence.

Thanks,
Jason



+    unsigned int *__kaslr_offset = (unsigned int *)(KERNELBASE + 0x58);
+    unsigned int *__run_at_load = (unsigned int *)(KERNELBASE + 0x5c);
+
+    if (*__run_at_load == 1)
+        return;
+
+    /* Setup flat device-tree pointer */
+    initial_boot_params = dt_ptr;
+#endif
+
      kernel_sz = (unsigned long)_end - (unsigned long)_stext;
      offset = kaslr_choose_location(dt_ptr, size, kernel_sz);
@@ -372,6 +394,7 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
      kernstart_virt_addr += offset;
      kernstart_addr += offset;
+#ifdef CONFIG_PPC32
      is_second_reloc = 1;
      if (offset >= SZ_64M) {
@@ -381,6 +404,10 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
          /* Create kernel map to relocate in */
          create_kaslr_tlb_entry(1, tlb_virt, tlb_phys);
      }
+#else
+    *__kaslr_offset = kernstart_virt_addr - KERNELBASE;
+    *__run_at_load = 1;
+#endif
      /* Copy the kernel to it's new location and run */
      memcpy((void *)kernstart_virt_addr, (void *)_stext, kernel_sz);


Christophe

.


.




[Index of Archives]     [Linux Samsung SoC]     [Linux Rockchip SoC]     [Linux Actions SoC]     [Linux for Synopsys ARC Processors]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]


  Powered by Linux