[PATCH v8 00/30] Initial Prefixed Instruction support

Jordan Niethe jniethe5 at gmail.com
Thu May 14 20:33:48 AEST 2020


On Thu, May 14, 2020 at 3:31 PM Christophe Leroy
<christophe.leroy at csgroup.eu> wrote:
>
>
>
> Le 06/05/2020 à 05:40, Jordan Niethe a écrit :
> > A future revision of the ISA will introduce prefixed instructions. A
> > prefixed instruction is composed of a 4-byte prefix followed by a
> > 4-byte suffix.
> >
> > All prefixes have the major opcode 1. A prefix will never be a valid
> > word instruction. A suffix may be an existing word instruction or a
> > new instruction.
> >
> > This series enables prefixed instructions and extends the instruction
> > emulation to support them. Then the places where prefixed instructions
> > might need to be emulated are updated.
> >
> > v8 incorporates feedback from Alistair Popple and Balamuruhan Suriyakumar.
> > The major changes:
> >      - Fix some style issues
> >      - Fix __patch_instruction() on big endian
> >      - Reintroduce v3's forbidding breakpoints on second word of prefix
> >        instructions for kprobes and xmon. Missed this when changing to
> >        using a data type.
> >      - Use the data type in some places that were missed.
>
> Checkpatch seems to report the following warnings for pmac32_defconfig,
> are they harmless ?
>
> +arch/powerpc/kernel/align.c:307:13: warning: cast removes address space
> '<asn:1>' of expression
> +arch/powerpc/kernel/align.c:307:13: warning: cast removes address space
> '<asn:1>' of expression
> +arch/powerpc/kernel/align.c:307:13: warning: cast removes address space
> '<asn:1>' of expression
> +arch/powerpc/kernel/align.c:307:13: warning: cast removes address space
> '<asn:1>' of expression
> +arch/powerpc/kernel/align.c:307:13: warning: cast removes address space
> '<asn:1>' of expression
> +arch/powerpc/kernel/align.c:307:13: warning: incorrect type in argument
> 1 (different address spaces) expected void const volatile [noderef]
> <asn:1> * got unsigned int [usertype] *
> +arch/powerpc/kernel/align.c:307:13: warning: incorrect type in
> initializer (different address spaces) expected unsigned int [noderef]
> <asn:1> *__gu_addr got unsigned int [usertype] *
> +arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: cast removes
> address space '<asn:1>' of expression
> +arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: cast removes
> address space '<asn:1>' of expression
> +arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: cast removes
> address space '<asn:1>' of expression
> +arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: cast removes
> address space '<asn:1>' of expression
> +arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: cast removes
> address space '<asn:1>' of expression
> -arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: incorrect type in
> argument 1 (different address spaces) expected void const volatile
> [noderef] <asn:1> * got unsigned int *
> +arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: incorrect type in
> argument 1 (different address spaces) expected void const volatile
> [noderef] <asn:1> * got unsigned int [usertype] *
> -arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: incorrect type in
> initializer (different address spaces) expected unsigned int [noderef]
> <asn:1> *__gu_addr got unsigned int *
> +arch/powerpc/kernel/hw_breakpoint.c:XX:13: warning: incorrect type in
> initializer (different address spaces) expected unsigned int [noderef]
> <asn:1> *__gu_addr got unsigned int [usertype] *
> +arch/powerpc/kernel/vecemu.c:269:13: warning: cast removes address
> space '<asn:1>' of expression
> +arch/powerpc/kernel/vecemu.c:269:13: warning: cast removes address
> space '<asn:1>' of expression
> +arch/powerpc/kernel/vecemu.c:269:13: warning: cast removes address
> space '<asn:1>' of expression
> +arch/powerpc/kernel/vecemu.c:269:13: warning: cast removes address
> space '<asn:1>' of expression
> +arch/powerpc/kernel/vecemu.c:269:13: warning: cast removes address
> space '<asn:1>' of expression
> +arch/powerpc/kernel/vecemu.c:269:13: warning: incorrect type in
> argument 1 (different address spaces) expected void const volatile
> [noderef] <asn:1> * got unsigned int [usertype] *
> +arch/powerpc/kernel/vecemu.c:269:13: warning: incorrect type in
> initializer (different address spaces) expected unsigned int [noderef]
> <asn:1> *__gu_addr got unsigned int [usertype] *
> +arch/powerpc/lib/inst.c:55:37: warning: incorrect type in argument 2
> (different address spaces) expected void const [noderef] <asn:1> *src
> got struct ppc_inst *nip
> +arch/powerpc/mm/fault.c:284:59: warning: incorrect type in argument 2
> (different address spaces) expected struct ppc_inst *nip got struct
> ppc_inst [noderef] <asn:1> *
Thanks, I was missing some __user.
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -106,10 +106,10 @@ static inline int __access_ok(unsigned long
addr, unsigned long size,
        __put_user_nosleep((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))

 #define __get_user_instr(x, ptr) \
-       __get_user_nocheck((x).val, (u32 *)(ptr), sizeof(u32), true)
+       __get_user_nocheck((x).val, (u32 __user *)(ptr), sizeof(u32), true)

 #define __get_user_instr_inatomic(x, ptr) \
-       __get_user_nosleep((x).val, (u32 *)(ptr), sizeof(u32))
+       __get_user_nosleep((x).val, (u32 __user *)(ptr), sizeof(u32))
 extern long __put_user_bad(void);

 /*

--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h
@@ -38,6 +38,6 @@ static inline bool ppc_inst_equal(struct ppc_inst x,
struct ppc_inst y)
 }

 int probe_user_read_inst(struct ppc_inst *inst,
-                        struct ppc_inst *nip);
+                        struct ppc_inst __user *nip);

 #endif /* _ASM_INST_H */
diff --git a/arch/powerpc/lib/inst.c b/arch/powerpc/lib/inst.c
index eaf786afad2b..c15611086d26 100644
--- a/arch/powerpc/lib/inst.c
+++ b/arch/powerpc/lib/inst.c
@@ -7,7 +7,7 @@
 #include <asm/inst.h>

 int probe_user_read_inst(struct ppc_inst *inst,
-                        struct ppc_inst *nip)
+                        struct ppc_inst __user *nip)
 {
        unsigned int val;
        int err;


>
> Christophe
>
> >
> > v7 fixes compilation issues for some configs reported by Alistair
> > Popple.
> >
> > v6 is based on feedback from Balamuruhan Suriyakumar, Alistair Popple,
> > Christophe Leroy and Segher Boessenkool.
> > The major changes:
> >      - Use the instruction type in more places that had been missed before
> >      - Fix issues with ppc32
> >      - Introduce new self tests for code patching and feature fixups
> >
> > v5 is based on feedback from Nick Piggins, Michael Ellerman, Balamuruhan
> > Suriyakumar and Alistair Popple.
> > The major changes:
> >      - The ppc instruction type is now a struct
> >      - Series now just based on next
> >      - ppc_inst_masked() dropped
> >      - Space for xmon breakpoints allocated in an assembly file
> >      - "Add prefixed instructions to instruction data type" patch seperated in
> >        to smaller patches
> >      - Calling convention for create_branch() is changed
> >      - Some places which had not been updated to use the data type are now updated
> >
> > v4 is based on feedback from Nick Piggins, Christophe Leroy and Daniel Axtens.
> > The major changes:
> >      - Move xmon breakpoints from data section to text section
> >      - Introduce a data type for instructions on powerpc
> >
> > v3 is based on feedback from Christophe Leroy. The major changes:
> >      - Completely replacing store_inst() with patch_instruction() in
> >        xmon
> >      - Improve implementation of mread_instr() to not use mread().
> >      - Base the series on top of
> >        https://patchwork.ozlabs.org/patch/1232619/ as this will effect
> >        kprobes.
> >      - Some renaming and simplification of conditionals.
> >
> > v2 incorporates feedback from Daniel Axtens and and Balamuruhan
> > S. The major changes are:
> >      - Squashing together all commits about SRR1 bits
> >      - Squashing all commits for supporting prefixed load stores
> >      - Changing abbreviated references to sufx/prfx -> suffix/prefix
> >      - Introducing macros for returning the length of an instruction
> >      - Removing sign extension flag from pstd/pld in sstep.c
> >      - Dropping patch  "powerpc/fault: Use analyse_instr() to check for
> >        store with updates to sp" from the series, it did not really fit
> >        with prefixed enablement in the first place and as reported by Greg
> >        Kurz did not work correctly.
> >
> >
> > Alistair Popple (1):
> >    powerpc: Enable Prefixed Instructions
> >
> > Jordan Niethe (29):
> >    powerpc/xmon: Remove store_inst() for patch_instruction()
> >    powerpc/xmon: Move breakpoint instructions to own array
> >    powerpc/xmon: Move breakpoints to text section
> >    powerpc/xmon: Use bitwise calculations in_breakpoint_table()
> >    powerpc: Change calling convention for create_branch() et. al.
> >    powerpc: Use a macro for creating instructions from u32s
> >    powerpc: Use an accessor for instructions
> >    powerpc: Use a function for getting the instruction op code
> >    powerpc: Use a function for byte swapping instructions
> >    powerpc: Introduce functions for instruction equality
> >    powerpc: Use a datatype for instructions
> >    powerpc: Use a function for reading instructions
> >    powerpc: Add a probe_user_read_inst() function
> >    powerpc: Add a probe_kernel_read_inst() function
> >    powerpc/kprobes: Use patch_instruction()
> >    powerpc: Define and use __get_user_instr{,inatomic}()
> >    powerpc: Introduce a function for reporting instruction length
> >    powerpc/xmon: Use a function for reading instructions
> >    powerpc/xmon: Move insertion of breakpoint for xol'ing
> >    powerpc: Make test_translate_branch() independent of instruction
> >      length
> >    powerpc: Define new SRR1 bits for a future ISA version
> >    powerpc: Add prefixed instructions to instruction data type
> >    powerpc: Test prefixed code patching
> >    powerpc: Test prefixed instructions in feature fixups
> >    powerpc/xmon: Don't allow breakpoints on suffixes
> >    powerpc/kprobes: Don't allow breakpoints on suffixes
> >    powerpc: Support prefixed instructions in alignment handler
> >    powerpc sstep: Add support for prefixed load/stores
> >    powerpc sstep: Add support for prefixed fixed-point arithmetic
> >
> >   arch/powerpc/include/asm/code-patching.h  |  37 +-
> >   arch/powerpc/include/asm/inst.h           | 107 +++++
> >   arch/powerpc/include/asm/kprobes.h        |   2 +-
> >   arch/powerpc/include/asm/ppc-opcode.h     |   3 +
> >   arch/powerpc/include/asm/reg.h            |   7 +-
> >   arch/powerpc/include/asm/sstep.h          |  15 +-
> >   arch/powerpc/include/asm/uaccess.h        |  43 ++
> >   arch/powerpc/include/asm/uprobes.h        |   7 +-
> >   arch/powerpc/kernel/align.c               |  13 +-
> >   arch/powerpc/kernel/asm-offsets.c         |   8 +
> >   arch/powerpc/kernel/crash_dump.c          |   7 +-
> >   arch/powerpc/kernel/epapr_paravirt.c      |   7 +-
> >   arch/powerpc/kernel/hw_breakpoint.c       |   5 +-
> >   arch/powerpc/kernel/jump_label.c          |   5 +-
> >   arch/powerpc/kernel/kgdb.c                |   9 +-
> >   arch/powerpc/kernel/kprobes.c             |  37 +-
> >   arch/powerpc/kernel/mce_power.c           |   5 +-
> >   arch/powerpc/kernel/module_64.c           |   3 +-
> >   arch/powerpc/kernel/optprobes.c           | 102 +++--
> >   arch/powerpc/kernel/optprobes_head.S      |   3 +
> >   arch/powerpc/kernel/security.c            |  12 +-
> >   arch/powerpc/kernel/setup_32.c            |   8 +-
> >   arch/powerpc/kernel/trace/ftrace.c        | 168 ++++----
> >   arch/powerpc/kernel/traps.c               |  20 +-
> >   arch/powerpc/kernel/uprobes.c             |   5 +-
> >   arch/powerpc/kernel/vecemu.c              |  20 +-
> >   arch/powerpc/kvm/book3s_hv_nested.c       |   2 +-
> >   arch/powerpc/kvm/book3s_hv_rm_mmu.c       |   2 +-
> >   arch/powerpc/kvm/emulate_loadstore.c      |   2 +-
> >   arch/powerpc/lib/Makefile                 |   2 +-
> >   arch/powerpc/lib/code-patching.c          | 319 +++++++++------
> >   arch/powerpc/lib/feature-fixups-test.S    |  69 ++++
> >   arch/powerpc/lib/feature-fixups.c         | 160 ++++++--
> >   arch/powerpc/lib/inst.c                   |  70 ++++
> >   arch/powerpc/lib/sstep.c                  | 459 +++++++++++++++-------
> >   arch/powerpc/lib/test_code-patching.S     |  20 +
> >   arch/powerpc/lib/test_emulate_step.c      |  56 +--
> >   arch/powerpc/mm/fault.c                   |  15 +-
> >   arch/powerpc/mm/nohash/8xx.c              |   5 +-
> >   arch/powerpc/perf/8xx-pmu.c               |   9 +-
> >   arch/powerpc/perf/core-book3s.c           |   4 +-
> >   arch/powerpc/platforms/86xx/mpc86xx_smp.c |   5 +-
> >   arch/powerpc/platforms/powermac/smp.c     |   5 +-
> >   arch/powerpc/xmon/Makefile                |   2 +-
> >   arch/powerpc/xmon/xmon.c                  | 122 ++++--
> >   arch/powerpc/xmon/xmon_bpts.S             |  11 +
> >   arch/powerpc/xmon/xmon_bpts.h             |  14 +
> >   47 files changed, 1409 insertions(+), 602 deletions(-)
> >   create mode 100644 arch/powerpc/include/asm/inst.h
> >   create mode 100644 arch/powerpc/lib/inst.c
> >   create mode 100644 arch/powerpc/lib/test_code-patching.S
> >   create mode 100644 arch/powerpc/xmon/xmon_bpts.S
> >   create mode 100644 arch/powerpc/xmon/xmon_bpts.h
> >


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