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Fri, 22 Dec 2023 09:12:39 -0800 (PST) From: Leonardo Bras To: Guo Ren Cc: Leonardo Bras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Eric Biederman , Kees Cook , Oleg Nesterov , Conor Dooley , Andy Chiu , Greg Ungerer , Vincent Chen , Xiao Wang , Charlie Jenkins , Andrew Morton , Alexandre Ghiti , Kemeng Shi , David Hildenbrand , "Matthew Wilcox (Oracle)" , Qinglin Pan , Greentime Hu , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , =?iso-8859-1?Q?Cl=E9ment_L=E9ger?= , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 2/4] riscv: add compile-time test into is_compat_task() Date: Fri, 22 Dec 2023 14:12:22 -0300 Message-ID: X-Mailer: git-send-email 2.43.0 In-Reply-To: References: <20231222074605.452452-1-leobras@redhat.com> <20231222074605.452452-3-leobras@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1BAA5C0009 X-Stat-Signature: nf7wh3mnt1d39qmh8sy7pmqs6wct67bq X-HE-Tag: 1703265163-308464 X-HE-Meta: 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 hHQ55S+x 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Dec 22, 2023 at 05:35:20PM +0800, Guo Ren wrote: > On Fri, Dec 22, 2023 at 5:02 PM Leonardo Bras wrote: > > > > Currently several places will test for CONFIG_COMPAT before testing > > is_compat_task(), probably in order to avoid a run-time test into the task > > structure. > > > > Since is_compat_task() is an inlined function, it would be helpful to add a > > compile-time test of CONFIG_COMPAT, making sure it always returns zero when > > the option is not enabled during the kernel build. > > > > With this, the compiler is able to understand in build-time that > > is_compat_task() will always return 0, and optimize-out some of the extra > > code introduced by the option. > > > > This will also allow removing a lot #ifdefs that were introduced, and make > > the code more clean. > > > > Signed-off-by: Leonardo Bras > > --- > > arch/riscv/include/asm/compat.h | 3 +++ > > arch/riscv/include/asm/elf.h | 4 ---- > > arch/riscv/include/asm/pgtable.h | 6 ------ > > arch/riscv/include/asm/processor.h | 4 ++-- > > 4 files changed, 5 insertions(+), 12 deletions(-) > > > > diff --git a/arch/riscv/include/asm/compat.h b/arch/riscv/include/asm/compat.h > > index 2ac955b51148f..91517b51b8e27 100644 > > --- a/arch/riscv/include/asm/compat.h > > +++ b/arch/riscv/include/asm/compat.h > > @@ -14,6 +14,9 @@ > > > > static inline int is_compat_task(void) > > { > > + if (!IS_ENABLED(CONFIG_COMPAT)) > > + return 0; > > + > > return test_thread_flag(TIF_32BIT); > > } > > > > diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h > > index 59a08367fddd7..2e88257cafaea 100644 > > --- a/arch/riscv/include/asm/elf.h > > +++ b/arch/riscv/include/asm/elf.h > > @@ -53,13 +53,9 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr); > > #define ELF_ET_DYN_BASE ((DEFAULT_MAP_WINDOW / 3) * 2) > > > > #ifdef CONFIG_64BIT > > -#ifdef CONFIG_COMPAT > > #define STACK_RND_MASK (is_compat_task() ? \ > > 0x7ff >> (PAGE_SHIFT - 12) : \ > > 0x3ffff >> (PAGE_SHIFT - 12)) > > -#else > > -#define STACK_RND_MASK (0x3ffff >> (PAGE_SHIFT - 12)) > > -#endif > > #endif > > > > /* > > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > > index 1d472b31e0cfe..ea5b269be223a 100644 > > --- a/arch/riscv/include/asm/pgtable.h > > +++ b/arch/riscv/include/asm/pgtable.h > > @@ -127,16 +127,10 @@ > > #define VA_USER_SV48 (UL(1) << (VA_BITS_SV48 - 1)) > > #define VA_USER_SV57 (UL(1) << (VA_BITS_SV57 - 1)) > > > > -#ifdef CONFIG_COMPAT > > #define MMAP_VA_BITS_64 ((VA_BITS >= VA_BITS_SV48) ? VA_BITS_SV48 : VA_BITS) > > #define MMAP_MIN_VA_BITS_64 (VA_BITS_SV39) > > #define MMAP_VA_BITS (is_compat_task() ? VA_BITS_SV32 : MMAP_VA_BITS_64) > > #define MMAP_MIN_VA_BITS (is_compat_task() ? VA_BITS_SV32 : MMAP_MIN_VA_BITS_64) > > -#else > > -#define MMAP_VA_BITS ((VA_BITS >= VA_BITS_SV48) ? VA_BITS_SV48 : VA_BITS) > > -#define MMAP_MIN_VA_BITS (VA_BITS_SV39) > > -#endif /* CONFIG_COMPAT */ > > - > > #else > > #include > > #endif /* CONFIG_64BIT */ > > diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h > > index f19f861cda549..ed32e53e55999 100644 > > --- a/arch/riscv/include/asm/processor.h > > +++ b/arch/riscv/include/asm/processor.h > > @@ -22,7 +22,7 @@ > > ({ \ > > unsigned long mmap_end; \ > > typeof(addr) _addr = (addr); \ > > - if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \ > > + if ((_addr) == 0 || is_compat_task()) \ > > mmap_end = STACK_TOP_MAX; \ > > else if ((_addr) >= VA_USER_SV57) \ > > mmap_end = STACK_TOP_MAX; \ > > @@ -39,7 +39,7 @@ > > typeof(addr) _addr = (addr); \ > > typeof(base) _base = (base); \ > > unsigned long rnd_gap = DEFAULT_MAP_WINDOW - (_base); \ > > - if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \ > > + if ((_addr) == 0 || is_compat_task()) \ > > mmap_base = (_base); \ > > else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \ > > mmap_base = VA_USER_SV57 - rnd_gap; \ > > -- > > 2.43.0 > > > Reviewed-by: Guo Ren Thanks! Leo > > -- > Best Regards > Guo Ren >