kernel/linux.git/arch/powerpc/include/asm/inst.h, branch v6.19.12

powerpc: Drop unnecessary initializations in __copy_inst_from_kernel_nofault()

2025-08-28T23:58:44+00:00

Now that the minimum supported version of LLVM for building the kernel has been bumped to 15.0.0, the zero initializations of val and suffix added by commit 0d76914a4c99 ("powerpc/inst: Optimise copy_inst_from_kernel_nofault()") to avoid a bogus case of -Wuninitialized can be dropped because the preprocessor condition is always false. Reviewed-by: Kees Cook Reviewed-by: Christophe Leroy Link: https://lore.kernel.org/r/20250821-bump-min-llvm-ver-15-v2-6-635f3294e5f0@kernel.org Signed-off-by: Nathan Chancellor

powerpc/64: Drop ppc_inst_as_str()

2022-06-29T09:37:07+00:00

The ppc_inst_as_str() macro tries to make printing variable length, aka "prefixed", instructions convenient. It mostly succeeds, but it does hide an on-stack buffer, which triggers stack protector. More problematically it doesn't compile at all with GCC 12, with -Wdangling-pointer, due to the fact that it returns the char buffer declared inside the macro: arch/powerpc/kernel/trace/ftrace.c: In function '__ftrace_modify_call': ./include/linux/printk.h:475:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=] 475 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__) ... arch/powerpc/kernel/trace/ftrace.c:567:17: note: in expansion of macro 'pr_err' 567 | pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op)); | ^~~~~~ ./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here 156 | char __str[PPC_INST_STR_LEN]; \ | ^~~~~ This could be fixed by having the caller declare the buffer, but in some places there'd need to be two buffers. In all cases where ppc_inst_as_str() is used the output is not really meant for user consumption, it's almost always indicative of a kernel bug. A simpler solution is to just print the value as an unsigned long. For normal instructions the output is identical. For prefixed instructions the value is printed as a single 64-bit quantity, whereas previously the low half was printed first. But that is good enough for debug output, especially as prefixed instructions will be rare in kernel code in practice. Old: c000000000111170 60420000 ori r2,r2,0 c000000000111174 04100001 e580fb00 .long 0xe580fb0004100001 New: c00000000010f90c 60420000 ori r2,r2,0 c00000000010f910 e580fb0004100001 .long 0xe580fb0004100001 Reported-by: Bagas Sanjaya Reported-by: Petr Mladek Signed-off-by: Michael Ellerman Tested-by: Bagas Sanjaya Link: https://lore.kernel.org/r/20220531065936.3674348-1-mpe@ellerman.id.au

powerpc/inst: Add __copy_inst_from_kernel_nofault()

2022-05-22T05:58:26+00:00

On the same model as get_user() versus __get_user(), introduce __copy_inst_from_kernel_nofault() which doesn't check address. To be used by callers that have already checked that the adress is a kernel address. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1f3702890d6dbd64702b61834753bcc96851c18c.1652074503.git.christophe.leroy@csgroup.eu

powerpc/code-patching: Replace patch_instruction() by ppc_inst_write() in selftests

2021-12-23T11:36:58+00:00

The purpose of selftests is to check that instructions are properly formed. Not to check that they properly run. For that test it uses normal memory, not special test memory. In preparation of a future patch enforcing patch_instruction() to be used only on valid text areas, implement a ppc_inst_write() instruction which is the complement of ppc_inst_read(). This new function writes the formated instruction in valid kernel memory and doesn't bother about icache. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/7cf5335cc07ca9b6f8cdaa20ca9887fce4df3bea.1638446239.git.christophe.leroy@csgroup.eu

powerpc/inst: Optimise copy_inst_from_kernel_nofault()

2021-12-09T11:41:21+00:00

copy_inst_from_kernel_nofault() uses copy_from_kernel_nofault() to copy one or two 32bits words. This means calling an out-of-line function which itself calls back copy_from_kernel_nofault_allowed() then performs a generic copy with loops. Rewrite copy_inst_from_kernel_nofault() to do everything at a single place and use __get_kernel_nofault() directly to perform single accesses without loops. Allthough the generic function uses pagefault_disable(), it is not required on powerpc because do_page_fault() bails earlier when a kernel mode fault happens on a kernel address. As the function has now become very small, inline it. With this change, on an 8xx the time spent in the loop in ftrace_replace_code() is reduced by 23% at function tracer activation and 27% at nop tracer activation. The overall time to activate function tracer (measured with shell command 'time') is 570ms before the patch and 470ms after the patch. Even vmlinux size is reduced (by 152 instruction). Before the patch: 00000018 : 18: 94 21 ff e0 stwu r1,-32(r1) 1c: 7c 08 02 a6 mflr r0 20: 38 a0 00 04 li r5,4 24: 93 e1 00 1c stw r31,28(r1) 28: 7c 7f 1b 78 mr r31,r3 2c: 38 61 00 08 addi r3,r1,8 30: 90 01 00 24 stw r0,36(r1) 34: 48 00 00 01 bl 34 34: R_PPC_REL24 copy_from_kernel_nofault 38: 2c 03 00 00 cmpwi r3,0 3c: 40 82 00 0c bne 48 40: 81 21 00 08 lwz r9,8(r1) 44: 91 3f 00 00 stw r9,0(r31) 48: 80 01 00 24 lwz r0,36(r1) 4c: 83 e1 00 1c lwz r31,28(r1) 50: 38 21 00 20 addi r1,r1,32 54: 7c 08 03 a6 mtlr r0 58: 4e 80 00 20 blr After the patch (before inlining): 00000018 : 18: 3d 20 b0 00 lis r9,-20480 1c: 7c 04 48 40 cmplw r4,r9 20: 7c 69 1b 78 mr r9,r3 24: 41 80 00 14 blt 38 28: 81 44 00 00 lwz r10,0(r4) 2c: 38 60 00 00 li r3,0 30: 91 49 00 00 stw r10,0(r9) 34: 4e 80 00 20 blr 38: 38 60 ff de li r3,-34 3c: 4e 80 00 20 blr 40: 38 60 ff f2 li r3,-14 44: 4e 80 00 20 blr Signed-off-by: Christophe Leroy [mpe: Add clang workaround, with version check as suggested by Nathan] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/0d5b12183d5176dd702d29ad94c39c384e51c78f.1638208156.git.christophe.leroy@csgroup.eu

powerpc/inst: Move ppc_inst_t definition in asm/reg.h

2021-12-09T11:41:21+00:00

Because of circular inclusion of asm/hw_breakpoint.h, we need to move definition of asm/reg.h outside of inst.h so that asm/hw_breakpoint.h gets it without including asm/inst.h Also remove asm/inst.h from asm/uprobes.h as it's not needed anymore. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/4b79f1491118af96b1ac0735e74aeca02ea4c04e.1638208156.git.christophe.leroy@csgroup.eu

powerpc/inst: Define ppc_inst_t as u32 on PPC32

2021-12-09T11:41:21+00:00

Unlike PPC64 ABI, PPC32 uses the stack to pass a parameter defined as a struct, even when the struct has a single simple element. To avoid that, define ppc_inst_t as u32 on PPC32. Keep it as 'struct ppc_inst' when __CHECKER__ is defined so that sparse can perform type checking. Also revert commit 511eea5e2ccd ("powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32") as now the instruction to be emulated is passed as a register to emulate_step(). Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c6d0c46f598f76ad0b0a88bc0d84773bd921b17c.1638208156.git.christophe.leroy@csgroup.eu

powerpc/inst: Define ppc_inst_t

2021-12-09T11:41:21+00:00

In order to stop using 'struct ppc_inst' on PPC32, define a ppc_inst_t typedef. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/fe5baa2c66fea9db05a8b300b3e8d2880a42596c.1638208156.git.christophe.leroy@csgroup.eu

powerpc/inst: Refactor ___get_user_instr()

2021-12-09T11:41:20+00:00

PPC64 version of ___get_user_instr() can be used for PPC32 as well, by simply disabling the suffix part with IS_ENABLED(CONFIG_PPC64). Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1f0ede830ccb33a659119a55cb590820c27004db.1638208156.git.christophe.leroy@csgroup.eu

powerpc/inst: Refactor PPC32 and PPC64 versions

2021-06-16T14:09:06+00:00

ppc_inst() ppc_inst_prefixed() ppc_inst_swab() can easily be made common to both PPC32 and PPC64. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/d54c63dcac6d190e1cc0d2fe3259d6e621928cdf.1621516826.git.christophe.leroy@csgroup.eu