| Message ID | 200d273a83906a68a1c4a9298c415980737be811.1715781469.git.geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
| Series | ARM: Fix userspace enter on LPAE with CC_OPTIMIZE_FOR_SIZE=y | expand |
On Wed, 15 May 2024 at 16:02, Geert Uytterhoeven <geert+renesas@glider.be> wrote: > > Booting an LPAE-enabled kernel built with CONFIG_CC_OPTIMIZE_FOR_SIZE=y > fails when starting userspace: > > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 > CPU: 1 PID: 1 Comm: init Tainted: G W N 6.9.0-rc1-koelsch-00004-g7af5b901e847 #1930 > Hardware name: Generic R-Car Gen2 (Flattened Device Tree) > Call trace: > unwind_backtrace from show_stack+0x10/0x14 > show_stack from dump_stack_lvl+0x78/0xa8 > dump_stack_lvl from panic+0x118/0x398 > panic from do_exit+0x1ec/0x938 > do_exit from sys_exit_group+0x0/0x10 > ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 ]--- > > Add the missing memory clobber to cpu_set_ttbcr(), as suggested by > Russell King. > > Force inlining of uaccess_save_and_enable(), as suggested by Ard > Biesheuvel. > > The latter fixes booting on Koelsch. > > Fixes: 7af5b901e84743c6 ("ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement") > Closes: https://lore.kernel.org/r/CAMuHMdWTAJcZ9BReWNhpmsgkOzQxLNb5OhNYxzxv6D5TSh2fwQ@mail.gmail.com/ > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> This works around what appears to be a compiler bug (see my reply to the other thread), and this change (the __always_inline in particular) seems to work around it, so Acked-by: Ard Biesheuvel <ardb@kernel.org> > --- > Feel free to fold into the original commit. > > Apparently the "From: Catalin Marinas <catalin.marinas@arm.com>" in > https://lore.kernel.org/r/20240312-arm32-lpae-pan-v3-4-532647afcd38@linaro.org > is not reflected in commit 7af5b901e84743c6? > --- > arch/arm/include/asm/proc-fns.h | 2 +- > arch/arm/include/asm/uaccess.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/include/asm/proc-fns.h b/arch/arm/include/asm/proc-fns.h > index 9b3105a2a5e0691e..b4986a23d8528a50 100644 > --- a/arch/arm/include/asm/proc-fns.h > +++ b/arch/arm/include/asm/proc-fns.h > @@ -187,7 +187,7 @@ static inline unsigned int cpu_get_ttbcr(void) > > static inline void cpu_set_ttbcr(unsigned int ttbcr) > { > - asm("mcr p15, 0, %0, c2, c0, 2" : : "r" (ttbcr)); > + asm volatile("mcr p15, 0, %0, c2, c0, 2" : : "r" (ttbcr) : "memory"); > } > > #else /*!CONFIG_MMU */ > diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h > index 25d21d7d6e3efee0..6c9c16d767cfd5df 100644 > --- a/arch/arm/include/asm/uaccess.h > +++ b/arch/arm/include/asm/uaccess.h > @@ -47,7 +47,7 @@ static __always_inline void uaccess_restore(unsigned int flags) > > #elif defined(CONFIG_CPU_TTBR0_PAN) > > -static inline unsigned int uaccess_save_and_enable(void) > +static __always_inline unsigned int uaccess_save_and_enable(void) > { > unsigned int old_ttbcr = cpu_get_ttbcr(); > > -- > 2.34.1 >
On Wed, May 15, 2024 at 4:02 PM Geert Uytterhoeven <geert+renesas@glider.be> wrote: > Booting an LPAE-enabled kernel built with CONFIG_CC_OPTIMIZE_FOR_SIZE=y > fails when starting userspace: > > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 > CPU: 1 PID: 1 Comm: init Tainted: G W N 6.9.0-rc1-koelsch-00004-g7af5b901e847 #1930 > Hardware name: Generic R-Car Gen2 (Flattened Device Tree) > Call trace: > unwind_backtrace from show_stack+0x10/0x14 > show_stack from dump_stack_lvl+0x78/0xa8 > dump_stack_lvl from panic+0x118/0x398 > panic from do_exit+0x1ec/0x938 > do_exit from sys_exit_group+0x0/0x10 > ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 ]--- > > Add the missing memory clobber to cpu_set_ttbcr(), as suggested by > Russell King. > > Force inlining of uaccess_save_and_enable(), as suggested by Ard > Biesheuvel. > > The latter fixes booting on Koelsch. > > Fixes: 7af5b901e84743c6 ("ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement") > Closes: https://lore.kernel.org/r/CAMuHMdWTAJcZ9BReWNhpmsgkOzQxLNb5OhNYxzxv6D5TSh2fwQ@mail.gmail.com/ > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Thanks for digging into this, both you and Ard! And we found the root cause it seems. Yours, Linus Walleij
On 5/15/24 07:02, Geert Uytterhoeven wrote: > Booting an LPAE-enabled kernel built with CONFIG_CC_OPTIMIZE_FOR_SIZE=y > fails when starting userspace: > > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 > CPU: 1 PID: 1 Comm: init Tainted: G W N 6.9.0-rc1-koelsch-00004-g7af5b901e847 #1930 > Hardware name: Generic R-Car Gen2 (Flattened Device Tree) > Call trace: > unwind_backtrace from show_stack+0x10/0x14 > show_stack from dump_stack_lvl+0x78/0xa8 > dump_stack_lvl from panic+0x118/0x398 > panic from do_exit+0x1ec/0x938 > do_exit from sys_exit_group+0x0/0x10 > ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 ]--- > > Add the missing memory clobber to cpu_set_ttbcr(), as suggested by > Russell King. > > Force inlining of uaccess_save_and_enable(), as suggested by Ard > Biesheuvel. > > The latter fixes booting on Koelsch. > > Fixes: 7af5b901e84743c6 ("ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement") > Closes: https://lore.kernel.org/r/CAMuHMdWTAJcZ9BReWNhpmsgkOzQxLNb5OhNYxzxv6D5TSh2fwQ@mail.gmail.com/ > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
On Wed, May 15, 2024 at 12:46:38PM -0700, Florian Fainelli wrote: > On 5/15/24 07:02, Geert Uytterhoeven wrote: > > Booting an LPAE-enabled kernel built with CONFIG_CC_OPTIMIZE_FOR_SIZE=y > > fails when starting userspace: > > > > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 > > CPU: 1 PID: 1 Comm: init Tainted: G W N 6.9.0-rc1-koelsch-00004-g7af5b901e847 #1930 > > Hardware name: Generic R-Car Gen2 (Flattened Device Tree) > > Call trace: > > unwind_backtrace from show_stack+0x10/0x14 > > show_stack from dump_stack_lvl+0x78/0xa8 > > dump_stack_lvl from panic+0x118/0x398 > > panic from do_exit+0x1ec/0x938 > > do_exit from sys_exit_group+0x0/0x10 > > ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 ]--- > > > > Add the missing memory clobber to cpu_set_ttbcr(), as suggested by > > Russell King. > > > > Force inlining of uaccess_save_and_enable(), as suggested by Ard > > Biesheuvel. > > > > The latter fixes booting on Koelsch. > > > > Fixes: 7af5b901e84743c6 ("ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement") > > Closes: https://lore.kernel.org/r/CAMuHMdWTAJcZ9BReWNhpmsgkOzQxLNb5OhNYxzxv6D5TSh2fwQ@mail.gmail.com/ > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > > Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> This should be in linux-next now, if not by tomorrow - it was pushed out yesterday.
diff --git a/arch/arm/include/asm/proc-fns.h b/arch/arm/include/asm/proc-fns.h index 9b3105a2a5e0691e..b4986a23d8528a50 100644 --- a/arch/arm/include/asm/proc-fns.h +++ b/arch/arm/include/asm/proc-fns.h @@ -187,7 +187,7 @@ static inline unsigned int cpu_get_ttbcr(void) static inline void cpu_set_ttbcr(unsigned int ttbcr) { - asm("mcr p15, 0, %0, c2, c0, 2" : : "r" (ttbcr)); + asm volatile("mcr p15, 0, %0, c2, c0, 2" : : "r" (ttbcr) : "memory"); } #else /*!CONFIG_MMU */ diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 25d21d7d6e3efee0..6c9c16d767cfd5df 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -47,7 +47,7 @@ static __always_inline void uaccess_restore(unsigned int flags) #elif defined(CONFIG_CPU_TTBR0_PAN) -static inline unsigned int uaccess_save_and_enable(void) +static __always_inline unsigned int uaccess_save_and_enable(void) { unsigned int old_ttbcr = cpu_get_ttbcr();
Booting an LPAE-enabled kernel built with CONFIG_CC_OPTIMIZE_FOR_SIZE=y fails when starting userspace: Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 CPU: 1 PID: 1 Comm: init Tainted: G W N 6.9.0-rc1-koelsch-00004-g7af5b901e847 #1930 Hardware name: Generic R-Car Gen2 (Flattened Device Tree) Call trace: unwind_backtrace from show_stack+0x10/0x14 show_stack from dump_stack_lvl+0x78/0xa8 dump_stack_lvl from panic+0x118/0x398 panic from do_exit+0x1ec/0x938 do_exit from sys_exit_group+0x0/0x10 ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 ]--- Add the missing memory clobber to cpu_set_ttbcr(), as suggested by Russell King. Force inlining of uaccess_save_and_enable(), as suggested by Ard Biesheuvel. The latter fixes booting on Koelsch. Fixes: 7af5b901e84743c6 ("ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement") Closes: https://lore.kernel.org/r/CAMuHMdWTAJcZ9BReWNhpmsgkOzQxLNb5OhNYxzxv6D5TSh2fwQ@mail.gmail.com/ Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- Feel free to fold into the original commit. Apparently the "From: Catalin Marinas <catalin.marinas@arm.com>" in https://lore.kernel.org/r/20240312-arm32-lpae-pan-v3-4-532647afcd38@linaro.org is not reflected in commit 7af5b901e84743c6? --- arch/arm/include/asm/proc-fns.h | 2 +- arch/arm/include/asm/uaccess.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)