Message ID | 0aee964721cab7316cffde21a2ca223cee14d373.1647962456.git.christophe.leroy@csgroup.eu (mailing list archive) |
---|---|
State | Accepted |
Headers | show |
Series | Kill the time spent in patch_instruction() | expand |
On Tue, Mar 22, 2022 at 04:40:20PM +0100, Christophe Leroy wrote: > Once init is done, initmem is freed forever so no need to > test system_state at every call to patch_instruction(). > > Use jump_label. > > This reduces by 2% the time needed to activate ftrace on an 8xx. > It also causes the qemu mpc8544ds emulation to crash. BUG: Unable to handle kernel data access on write at 0xc122eb34 Faulting instruction address: 0xc001b580 Oops: Kernel access of bad area, sig: 11 [#1] BE PAGE_SIZE=4K MPC8544 DS Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 5.18.0-rc7-next-20220518 #1 NIP: c001b580 LR: c001b560 CTR: 00000003 REGS: c5107dd0 TRAP: 0300 Not tainted (5.18.0-rc7-next-20220518) MSR: 00009000 <EE,ME> CR: 24000882 XER: 00000000 DEAR: c122eb34 ESR: 00800000 GPR00: c001b560 c5107ec0 c5120020 10000000 00000000 00000078 0c000000 cfffffff GPR08: c001e9ec 00000001 00000007 00000000 44000882 00000000 c0005178 00000000 GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c1230000 NIP [c001b580] free_initmem+0x48/0xa8 LR [c001b560] free_initmem+0x28/0xa8 Call Trace: [c5107ec0] [c001b560] free_initmem+0x28/0xa8 (unreliable) [c5107ee0] [c00051b0] kernel_init+0x38/0x150 [c5107f00] [c001626c] ret_from_kernel_thread+0x5c/0x64 Instruction dump: 3fe0c123 912a00dc 90010024 48000665 3d20c218 8929fa65 2c090000 41820058 813feb34 2c090000 4082003c 39200001 <913feb34> 80010024 3cc0c114 83e1001c Reverting this patch fixes the problem. Guenter --- # bad: [736ee37e2e8eed7fe48d0a37ee5a709514d478b3] Add linux-next specific files for 20220518 # good: [42226c989789d8da4af1de0c31070c96726d990c] Linux 5.18-rc7 git bisect start 'HEAD' 'v5.18-rc7' # bad: [555b5fa93f08980ccb6bc8e196226046fe047901] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git git bisect bad 555b5fa93f08980ccb6bc8e196226046fe047901 # bad: [8f5ef5e622d3f217d6542779723566099f370c31] Merge branch 'for-next' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux.git git bisect bad 8f5ef5e622d3f217d6542779723566099f370c31 # good: [2b7d17d4b7c1ff40f58b0d32be40fc0bb6c582fb] soc: document merges git bisect good 2b7d17d4b7c1ff40f58b0d32be40fc0bb6c582fb # good: [4964f9250fbf76cb0b9c1124d5b9ab65de9bfd0e] Merge branch 'clk-next' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git git bisect good 4964f9250fbf76cb0b9c1124d5b9ab65de9bfd0e # bad: [18fae10a22071ccd0a2c44df2749ff482132774e] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git git bisect bad 18fae10a22071ccd0a2c44df2749ff482132774e # bad: [b4a5aaaa51e4ab7f03eec509d3710d50e52e87a6] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git git bisect bad b4a5aaaa51e4ab7f03eec509d3710d50e52e87a6 # bad: [b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5] powerpc/rtas: Keep MSR[RI] set when calling RTAS git bisect bad b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5 # good: [87ccc6684d3b57e3073f77cf28396b3037154193] powerpc/book3e: Fix sparse report in mm/nohash/fsl_book3e.c git bisect good 87ccc6684d3b57e3073f77cf28396b3037154193 # good: [f31c618373f2051a32e30002d8eacad7bbbd3885] powerpc: Sort and de-dup primary opcodes in ppc-opcode.h git bisect good f31c618373f2051a32e30002d8eacad7bbbd3885 # good: [9290c379d19774d8de6e2b895d756004dbad9ce5] powerpc/8xx: Simplify flush_tlb_kernel_range() git bisect good 9290c379d19774d8de6e2b895d756004dbad9ce5 # bad: [d8d2af70b98109418bb16ff6638d7c1c4336f7fe] cxl/ocxl: Prepare cleanup of powerpc's asm/prom.h git bisect bad d8d2af70b98109418bb16ff6638d7c1c4336f7fe # bad: [b033767848c4115e486b1a51946de3bee2ac0fa6] powerpc/code-patching: Use jump_label for testing freed initmem git bisect bad b033767848c4115e486b1a51946de3bee2ac0fa6 # good: [cb3ac45214c03852430979a43180371a44b74596] powerpc/code-patching: Don't call is_vmalloc_or_module_addr() without CONFIG_MODULES git bisect good cb3ac45214c03852430979a43180371a44b74596 # first bad commit: [b033767848c4115e486b1a51946de3bee2ac0fa6] powerpc/code-patching: Use jump_label for testing freed initmem
Le 19/05/2022 à 04:17, Guenter Roeck a écrit : > On Tue, Mar 22, 2022 at 04:40:20PM +0100, Christophe Leroy wrote: >> Once init is done, initmem is freed forever so no need to >> test system_state at every call to patch_instruction(). >> >> Use jump_label. >> >> This reduces by 2% the time needed to activate ftrace on an 8xx. >> > > It also causes the qemu mpc8544ds emulation to crash. > > BUG: Unable to handle kernel data access on write at 0xc122eb34 > Faulting instruction address: 0xc001b580 > Oops: Kernel access of bad area, sig: 11 [#1] > BE PAGE_SIZE=4K MPC8544 DS > Modules linked in: > CPU: 0 PID: 1 Comm: swapper Not tainted 5.18.0-rc7-next-20220518 #1 > NIP: c001b580 LR: c001b560 CTR: 00000003 > REGS: c5107dd0 TRAP: 0300 Not tainted (5.18.0-rc7-next-20220518) > MSR: 00009000 <EE,ME> CR: 24000882 XER: 00000000 > DEAR: c122eb34 ESR: 00800000 > GPR00: c001b560 c5107ec0 c5120020 10000000 00000000 00000078 0c000000 cfffffff > GPR08: c001e9ec 00000001 00000007 00000000 44000882 00000000 c0005178 00000000 > GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c1230000 > NIP [c001b580] free_initmem+0x48/0xa8 > LR [c001b560] free_initmem+0x28/0xa8 > Call Trace: > [c5107ec0] [c001b560] free_initmem+0x28/0xa8 (unreliable) > [c5107ee0] [c00051b0] kernel_init+0x38/0x150 > [c5107f00] [c001626c] ret_from_kernel_thread+0x5c/0x64 > Instruction dump: > 3fe0c123 912a00dc 90010024 48000665 3d20c218 8929fa65 2c090000 41820058 > 813feb34 2c090000 4082003c 39200001 <913feb34> 80010024 3cc0c114 83e1001c > > Reverting this patch fixes the problem. > That's strange. I was able to reproduce the problem. Removing the __ro_after_init in front of DEFINE_STATIC_KEY_FALSE(init_mem_is_free) fixes the problem. I can't understand why, mark_readonly() is called after free_initmem(). Christophe
Le 19/05/2022 à 08:27, Christophe Leroy a écrit : > > > Le 19/05/2022 à 04:17, Guenter Roeck a écrit : >> On Tue, Mar 22, 2022 at 04:40:20PM +0100, Christophe Leroy wrote: >>> Once init is done, initmem is freed forever so no need to >>> test system_state at every call to patch_instruction(). >>> >>> Use jump_label. >>> >>> This reduces by 2% the time needed to activate ftrace on an 8xx. >>> >> >> It also causes the qemu mpc8544ds emulation to crash. >> >> BUG: Unable to handle kernel data access on write at 0xc122eb34 >> Faulting instruction address: 0xc001b580 >> Oops: Kernel access of bad area, sig: 11 [#1] >> BE PAGE_SIZE=4K MPC8544 DS >> Modules linked in: >> CPU: 0 PID: 1 Comm: swapper Not tainted 5.18.0-rc7-next-20220518 #1 >> NIP: c001b580 LR: c001b560 CTR: 00000003 >> REGS: c5107dd0 TRAP: 0300 Not tainted (5.18.0-rc7-next-20220518) >> MSR: 00009000 <EE,ME> CR: 24000882 XER: 00000000 >> DEAR: c122eb34 ESR: 00800000 >> GPR00: c001b560 c5107ec0 c5120020 10000000 00000000 00000078 0c000000 cfffffff >> GPR08: c001e9ec 00000001 00000007 00000000 44000882 00000000 c0005178 00000000 >> GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >> GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c1230000 >> NIP [c001b580] free_initmem+0x48/0xa8 >> LR [c001b560] free_initmem+0x28/0xa8 >> Call Trace: >> [c5107ec0] [c001b560] free_initmem+0x28/0xa8 (unreliable) >> [c5107ee0] [c00051b0] kernel_init+0x38/0x150 >> [c5107f00] [c001626c] ret_from_kernel_thread+0x5c/0x64 >> Instruction dump: >> 3fe0c123 912a00dc 90010024 48000665 3d20c218 8929fa65 2c090000 41820058 >> 813feb34 2c090000 4082003c 39200001 <913feb34> 80010024 3cc0c114 83e1001c >> >> Reverting this patch fixes the problem. >> > > That's strange. > > I was able to reproduce the problem. > > Removing the __ro_after_init in front of > DEFINE_STATIC_KEY_FALSE(init_mem_is_free) fixes the problem. > > I can't understand why, mark_readonly() is called after free_initmem(). > Moving static_branch_enable(&init_mem_is_free) before mark_initmem_nx() also solves the problem. There must be something wrong with mark_initmem_nx(). Christophe
Le 19/05/2022 à 08:53, Christophe Leroy a écrit : > > > Le 19/05/2022 à 08:27, Christophe Leroy a écrit : >> >> >> Le 19/05/2022 à 04:17, Guenter Roeck a écrit : >>> On Tue, Mar 22, 2022 at 04:40:20PM +0100, Christophe Leroy wrote: >>>> Once init is done, initmem is freed forever so no need to >>>> test system_state at every call to patch_instruction(). >>>> >>>> Use jump_label. >>>> >>>> This reduces by 2% the time needed to activate ftrace on an 8xx. >>>> >>> >>> It also causes the qemu mpc8544ds emulation to crash. >>> >>> BUG: Unable to handle kernel data access on write at 0xc122eb34 >>> Faulting instruction address: 0xc001b580 >>> Oops: Kernel access of bad area, sig: 11 [#1] >>> BE PAGE_SIZE=4K MPC8544 DS >>> Modules linked in: >>> CPU: 0 PID: 1 Comm: swapper Not tainted 5.18.0-rc7-next-20220518 #1 >>> NIP: c001b580 LR: c001b560 CTR: 00000003 >>> REGS: c5107dd0 TRAP: 0300 Not tainted (5.18.0-rc7-next-20220518) >>> MSR: 00009000 <EE,ME> CR: 24000882 XER: 00000000 >>> DEAR: c122eb34 ESR: 00800000 >>> GPR00: c001b560 c5107ec0 c5120020 10000000 00000000 00000078 0c000000 >>> cfffffff >>> GPR08: c001e9ec 00000001 00000007 00000000 44000882 00000000 c0005178 >>> 00000000 >>> GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >>> 00000000 >>> GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >>> c1230000 >>> NIP [c001b580] free_initmem+0x48/0xa8 >>> LR [c001b560] free_initmem+0x28/0xa8 >>> Call Trace: >>> [c5107ec0] [c001b560] free_initmem+0x28/0xa8 (unreliable) >>> [c5107ee0] [c00051b0] kernel_init+0x38/0x150 >>> [c5107f00] [c001626c] ret_from_kernel_thread+0x5c/0x64 >>> Instruction dump: >>> 3fe0c123 912a00dc 90010024 48000665 3d20c218 8929fa65 2c090000 41820058 >>> 813feb34 2c090000 4082003c 39200001 <913feb34> 80010024 3cc0c114 >>> 83e1001c >>> >>> Reverting this patch fixes the problem. >>> >> >> That's strange. >> >> I was able to reproduce the problem. >> >> Removing the __ro_after_init in front of >> DEFINE_STATIC_KEY_FALSE(init_mem_is_free) fixes the problem. >> >> I can't understand why, mark_readonly() is called after free_initmem(). >> > > Moving static_branch_enable(&init_mem_is_free) before mark_initmem_nx() > also solves the problem. > > There must be something wrong with mark_initmem_nx(). > Fixing patch sent, see https://patchwork.ozlabs.org/project/linuxppc-dev/patch/2e35f0fd649c83c5add17a99514ac040767be93a.1652981047.git.christophe.leroy@csgroup.eu/ Christophe
diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h index 409483b2d0ce..bccc3a538b9f 100644 --- a/arch/powerpc/include/asm/code-patching.h +++ b/arch/powerpc/include/asm/code-patching.h @@ -22,6 +22,8 @@ #define BRANCH_SET_LINK 0x1 #define BRANCH_ABSOLUTE 0x2 +DECLARE_STATIC_KEY_FALSE(init_mem_is_free); + bool is_offset_in_branch_range(long offset); bool is_offset_in_cond_branch_range(long offset); int create_branch(ppc_inst_t *instr, const u32 *addr, diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 62692c6031bc..ab434c3853c9 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -8,6 +8,7 @@ #include <linux/init.h> #include <linux/cpuhotplug.h> #include <linux/uaccess.h> +#include <linux/jump_label.h> #include <asm/tlbflush.h> #include <asm/page.h> @@ -193,10 +194,12 @@ static int do_patch_instruction(u32 *addr, ppc_inst_t instr) #endif /* CONFIG_STRICT_KERNEL_RWX */ +__ro_after_init DEFINE_STATIC_KEY_FALSE(init_mem_is_free); + int patch_instruction(u32 *addr, ppc_inst_t instr) { /* Make sure we aren't patching a freed init section */ - if (system_state >= SYSTEM_FREEING_INITMEM && init_section_contains(addr, 4)) + if (static_branch_likely(&init_mem_is_free) && init_section_contains(addr, 4)) return 0; return do_patch_instruction(addr, instr); diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 8e301cd8925b..9710d4e0bf08 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -22,6 +22,7 @@ #include <asm/kasan.h> #include <asm/svm.h> #include <asm/mmzone.h> +#include <asm/code-patching.h> #include <mm/mmu_decl.h> @@ -311,6 +312,7 @@ void free_initmem(void) { ppc_md.progress = ppc_printk_progress; mark_initmem_nx(); + static_branch_enable(&init_mem_is_free); free_initmem_default(POISON_FREE_INITMEM); }
Once init is done, initmem is freed forever so no need to test system_state at every call to patch_instruction(). Use jump_label. This reduces by 2% the time needed to activate ftrace on an 8xx. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- arch/powerpc/include/asm/code-patching.h | 2 ++ arch/powerpc/lib/code-patching.c | 5 ++++- arch/powerpc/mm/mem.c | 2 ++ 3 files changed, 8 insertions(+), 1 deletion(-)