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Miller" , Andreas Larsson , linux-snps-arc@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-openrisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, Michal =?ISO-8859-1?Q?Such=E1nek?= , Jonathan Corbet , linux-doc@vger.kernel.org Date: Wed, 08 Jul 2026 16:59:18 -0400 In-Reply-To: <20260707190254.079478122@kernel.org> References: <20260707181957.433213175@kernel.org> <20260707190254.079478122@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote: > These functions integrate the stack randomization. >=20 > syscall_enter_from_user_mode_randomize_stack() has the advantage that the > randomization happens early right after enter_from_user_mode(). >=20 > In both cases also the overhead of get/put_cpu_var() in > add_random_kstack_offset() is avoided. >=20 > No functional change. >=20 > Signed-off-by: Thomas Gleixner > Cc: x86@kernel.org > --- > =C2=A0arch/x86/entry/syscall_32.c=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0 |=C2=A0=C2=A0 19 +++++-------------- > =C2=A0arch/x86/entry/syscall_64.c=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0 |=C2=A0=C2=A0=C2=A0 3 +-- > =C2=A0arch/x86/include/asm/entry-common.h |=C2=A0=C2=A0=C2=A0 1 - > =C2=A03 files changed, 6 insertions(+), 17 deletions(-) >=20 > --- a/arch/x86/entry/syscall_32.c > +++ b/arch/x86/entry/syscall_32.c > @@ -142,10 +142,9 @@ static __always_inline bool int80_is_ext > =C2=A0 * int80_is_external() below which calls into the APIC driver. > =C2=A0 * Identical for soft and external interrupts. > =C2=A0 */ > - enter_from_user_mode(regs); > + enter_from_user_mode_randomize_stack(regs); > =C2=A0 > =C2=A0 instrumentation_begin(); > - add_random_kstack_offset(); > =C2=A0 > =C2=A0 /* Validate that this is a soft interrupt to the extent possible *= / > =C2=A0 if (unlikely(int80_is_external())) > @@ -210,11 +209,9 @@ DEFINE_FREDENTRY_RAW(int80_emulation) > =C2=A0{ > =C2=A0 int nr; > =C2=A0 > - enter_from_user_mode(regs); > + enter_from_user_mode_randomize_stack(regs); > =C2=A0 > =C2=A0 instrumentation_begin(); > - add_random_kstack_offset(); > - > =C2=A0 /* > =C2=A0 * FRED pushed 0 into regs::orig_ax and regs::ax contains the > =C2=A0 * syscall number. > @@ -252,10 +249,10 @@ DEFINE_FREDENTRY_RAW(int80_emulation) > =C2=A0 * orig_ax, the int return value truncates it. This matches > =C2=A0 * the semantics of syscall_get_nr(). > =C2=A0 */ > - nr =3D syscall_enter_from_user_mode(regs, nr); > + nr =3D syscall_enter_from_user_mode_randomize_stack(regs, nr); > + > =C2=A0 instrumentation_begin(); > =C2=A0 > - add_random_kstack_offset(); > =C2=A0 do_syscall_32_irqs_on(regs, nr); > =C2=A0 > =C2=A0 instrumentation_end(); > @@ -268,15 +265,9 @@ static noinstr bool __do_fast_syscall_32 > =C2=A0 int nr =3D syscall_32_enter(regs); > =C2=A0 int res; > =C2=A0 > - /* > - * This cannot use syscall_enter_from_user_mode() as it has to > - * fetch EBP before invoking any of the syscall entry work > - * functions. > - */ > - enter_from_user_mode(regs); > + enter_from_user_mode_randomize_stack(regs); > =C2=A0 > =C2=A0 instrumentation_begin(); > - add_random_kstack_offset(); > =C2=A0 local_irq_enable(); > =C2=A0 /* Fetch EBP from where the vDSO stashed it. */ > =C2=A0 if (IS_ENABLED(CONFIG_X86_64)) { > --- a/arch/x86/entry/syscall_64.c > +++ b/arch/x86/entry/syscall_64.c > @@ -86,10 +86,9 @@ static __always_inline bool do_syscall_x > =C2=A0/* Returns true to return using SYSRET, or false to use IRET */ > =C2=A0__visible noinstr bool do_syscall_64(struct pt_regs *regs, int nr) > =C2=A0{ > - nr =3D syscall_enter_from_user_mode(regs, nr); > + nr =3D syscall_enter_from_user_mode_randomize_stack(regs, nr); > =C2=A0 > =C2=A0 instrumentation_begin(); > - add_random_kstack_offset(); > =C2=A0 > =C2=A0 if (!do_syscall_x64(regs, nr) && !do_syscall_x32(regs, nr) && nr != =3D -1) { > =C2=A0 /* Invalid system call, but still a system call. */ > --- a/arch/x86/include/asm/entry-common.h > +++ b/arch/x86/include/asm/entry-common.h > @@ -2,7 +2,6 @@ > =C2=A0#ifndef _ASM_X86_ENTRY_COMMON_H > =C2=A0#define _ASM_X86_ENTRY_COMMON_H > =C2=A0 > -#include > =C2=A0#include > =C2=A0 > =C2=A0#include Reviewed-by: Radu Rendec