* Re: [patch 03/18] entry: Provide [syscall_]enter_from_user_mode_randomize_stack()
From: Jinjie Ruan @ 2026-07-09 2:34 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Andy Lutomirski, Oleg Nesterov, Richard Henderson, Russell King,
Catalin Marinas, Guo Ren, Geert Uytterhoeven, Thomas Bogendoerfer,
Helge Deller, Yoshinori Sato, Richard Weinberger, Chris Zankel,
linux-arm-kernel, linux-alpha, linux-csky, linux-m68k, linux-mips,
linux-parisc, linux-sh, linux-um, Arnd Bergmann, Vineet Gupta,
Will Deacon, Brian Cain, Michal Simek, Dinh Nguyen,
David S. Miller, Andreas Larsson, linux-snps-arc, linux-hexagon,
linux-openrisc, sparclinux, linux-arch, Michal Suchánek,
Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.816918647@kernel.org>
On 7/8/2026 3:06 AM, Thomas Gleixner wrote:
> Randomizing the syscall stack can only happen after state is established
> via enter_from_user_mode() or syscall_enter_from_user_mode(). The earlier
> it happens the better.
>
> Provide two new macros to consolidate that:
>
> - enter_from_user_mode_randomize_stack()
> enter_from_user_mode();
> add_random_kstack_offset_irqsoff();
>
> - syscall_enter_from_user_mode_randomize_stack()
> enter_from_user_mode_randomize_stack();
> syscall_enter_from_user_mode_work();
>
> to reduce boiler plate code.
>
> Those are macros and not inline functions as the latter would limit the
> stack randomization scope to the inline function itself.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> ---
> include/linux/entry-common.h | 56 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 56 insertions(+)
>
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -6,6 +6,7 @@
> #include <linux/irq-entry-common.h>
> #include <linux/livepatch.h>
> #include <linux/ptrace.h>
> +#include <linux/randomize_kstack.h>
> #include <linux/resume_user_mode.h>
> #include <linux/seccomp.h>
> #include <linux/sched.h>
> @@ -150,6 +151,61 @@ static __always_inline long syscall_ente
> }
>
> /**
> + * enter_from_user_mode_randomize_stack - Establish state and add stack randomization
> + * before invoking syscall_enter_from_user_mode_work()
> + * @regs: Pointer to currents pt_regs
> + *
> + * Invoked from architecture specific syscall entry code with interrupts
> + * disabled. The calling code has to be non-instrumentable. When the function
> + * returns all state is correct, interrupts are still disabled and the
> + * subsequent functions can be instrumented.
> + *
> + * Implemented as a macro so that the stack randomization is effective
> + * throughout the function in which it is invoked. An inline would only make it
> + * effective in the scope of the inline function.
> + */
> +#define enter_from_user_mode_randomize_stack(regs) \
> +do { \
> + enter_from_user_mode(regs); \
> + instrumentation_begin(); \
> + add_random_kstack_offset_irqsoff(); \
> + instrumentation_end(); \
> +} while (0)
> +
> +/**
> + * syscall_enter_from_user_mode_randomize_stack - Establish state and check and handle work
> + * before invoking a syscall
> + * @regs: Pointer to currents pt_regs
> + * @syscall: The syscall number
> + *
> + * Invoked from architecture specific syscall entry code with interrupts
> + * disabled. The calling code has to be non-instrumentable. When the
> + * function returns all state is correct, interrupts are enabled and the
> + * subsequent functions can be instrumented.
> + *
> + * This is the combination of enter_from_user_mode_randomize_stack() and
> + * syscall_enter_from_user_mode_work() to be used when there is no
> + * architecture specific work to be done between the two.
> + *
> + * Returns: The original or a modified syscall number. See
> + * syscall_enter_from_user_mode_work() for further explanation.
> + *
> + * Implemented as a macro to make stack randomization effective in the calling
> + * scope.
> + */
> +#define syscall_enter_from_user_mode_randomize_stack(regs, syscall) \
> +({ \
> + enter_from_user_mode_randomize_stack(regs); \
> + \
> + instrumentation_begin(); \
> + local_irq_enable(); \
> + long _ret = syscall_enter_from_user_mode_work(regs, syscall); \
> + instrumentation_end(); \
> + \
> + _ret; \
> +})
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
> +
> +/**
> * syscall_enter_from_user_mode - Establish state and check and handle work
> * before invoking a syscall
> * @regs: Pointer to currents pt_regs
>
^ permalink raw reply
* Re: [PATCH 13/13] mm/mremap: convert mremap code to use vma_flags_t
From: Zi Yan @ 2026-07-09 2:28 UTC (permalink / raw)
To: Lorenzo Stoakes, Lance Yang
Cc: akpm, tsbogend, maddy, mpe, maarten.lankhorst, mripard,
tzimmermann, airlied, simona, l.stach, inki.dae, sw0312.kim,
kyungmin.park, krzk, peter.griffin, jani.nikula, joonas.lahtinen,
rodrigo.vivi, tursulin, robin.clark, lumag, lyude, dakr,
tomi.valkeinen, hjc, heiko, andy.yan, thierry.reding, mperttunen,
jonathanh, kraxel, dmitry.osipenko, zack.rusin, matthew.brost,
thomas.hellstrom, oleksandr_andrushchenko, deller, bcrl, viro,
brauner, muchun.song, osalvador, david, baolin.wang, liam, npache,
ryan.roberts, dev.jain, baohua, hughd, vbabka, rppt, surenb,
mhocko, jannh, pfalcato, kees, perex, tiwai, linux-mips,
linux-kernel, linuxppc-dev, dri-devel, etnaviv, linux-arm-kernel,
linux-samsung-soc, intel-gfx, linux-arm-msm, freedreno, nouveau,
linux-rockchip, linux-tegra, virtualization, intel-xe, xen-devel,
linux-fbdev, linux-aio, linux-fsdevel, linux-mm, linux-sound
In-Reply-To: <akaJx8Zt8kazlrjq@lucifer>
On Thu Jul 2, 2026 at 12:07 PM EDT, Lorenzo Stoakes wrote:
> On Thu, Jul 02, 2026 at 09:49:47PM +0800, Lance Yang wrote:
>>
>> On Mon, Jun 29, 2026 at 08:25:36PM +0100, Lorenzo Stoakes wrote:
>> >Replace use of the legacy vm_flags_t flags with vma_flags_t values
>> >throughout the mremap logic.
>> >
>> >Additionally update comments to reflect the changes to be consistent.
>> >
>> >No functional change intended.
>> >
>> >Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
>> >---
>>
>> The vm_flags_set() cases below spell out vma_start_write(), but the
>> vm_flags_clear() cases don't?
>
> Yep as I said elsewhere, implicitly taking the lock is terrible and me doing
> this is completely on purpose to get rid of that :)
>
> But I haven't been clear enough clearly, so I should put the argument as to why
> that's ok in the commit message.
>
> Will do so on respin.
How about also add a comment to vma_clear*() telling us a lock is not
needed and why like you explained a lock is needed for vma_set*()?
This asymmetry could confuse people.
This patch looks good to me.
Reviewed-by: Zi Yan <ziy@nvidia.com>
--
Best Regards,
Yan, Zi
^ permalink raw reply
* Re: [PATCH 12/13] mm/mprotect: convert mprotect code to use vma_flags_t
From: Zi Yan @ 2026-07-09 2:16 UTC (permalink / raw)
To: Lorenzo Stoakes, Lance Yang
Cc: akpm, tsbogend, maddy, mpe, maarten.lankhorst, mripard,
tzimmermann, airlied, simona, l.stach, inki.dae, sw0312.kim,
kyungmin.park, krzk, peter.griffin, jani.nikula, joonas.lahtinen,
rodrigo.vivi, tursulin, robin.clark, lumag, lyude, dakr,
tomi.valkeinen, hjc, heiko, andy.yan, thierry.reding, mperttunen,
jonathanh, kraxel, dmitry.osipenko, zack.rusin, matthew.brost,
thomas.hellstrom, oleksandr_andrushchenko, deller, bcrl, viro,
brauner, muchun.song, osalvador, david, baolin.wang, liam, npache,
ryan.roberts, dev.jain, baohua, hughd, vbabka, rppt, surenb,
mhocko, jannh, pfalcato, kees, perex, tiwai, linux-mips,
linux-kernel, linuxppc-dev, dri-devel, etnaviv, linux-arm-kernel,
linux-samsung-soc, intel-gfx, linux-arm-msm, freedreno, nouveau,
linux-rockchip, linux-tegra, virtualization, intel-xe, xen-devel,
linux-fbdev, linux-aio, linux-fsdevel, linux-mm, linux-sound
In-Reply-To: <akaIfhfbTCAdJm3H@lucifer>
On Thu Jul 2, 2026 at 11:53 AM EDT, Lorenzo Stoakes wrote:
> On Thu, Jul 02, 2026 at 12:09:17AM +0800, Lance Yang wrote:
>>
>> On Mon, Jun 29, 2026 at 08:25:35PM +0100, Lorenzo Stoakes wrote:
>> >Replace use of the legacy vm_flags_t flags with vma_flags_t values
>> >throughout the mprotect logic.
>> >
>> >Note that we retain the legacy vm_flags_t bit shifting code in
>> >do_mprotect_key(), deferring a vma_flags_t approach to this for the time
>> >being.
>> >
>> >Additionally update comments to reflect the changes to be consistent.
>> >
>> >No functional change intended.
>> >
>> >Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
>> >---
>> > mm/mprotect.c | 16 ++++++++--------
>> > 1 file changed, 8 insertions(+), 8 deletions(-)
>> >
>> >diff --git a/mm/mprotect.c b/mm/mprotect.c
>> >index 9cbf932b028c..c9504b2a2525 100644
>> >--- a/mm/mprotect.c
>> >+++ b/mm/mprotect.c
>> >@@ -40,7 +40,7 @@
>> >
>> > static bool maybe_change_pte_writable(struct vm_area_struct *vma, pte_t pte)
>> > {
>> >- if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
>> >+ if (WARN_ON_ONCE(!vma_test(vma, VMA_WRITE_BIT)))
>> > return false;
>> >
>> > /* Don't touch entries that are not even readable. */
>> >@@ -97,7 +97,7 @@ static bool can_change_shared_pte_writable(struct vm_area_struct *vma,
>> > bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
>> > pte_t pte)
>> > {
>> >- if (!(vma->vm_flags & VM_SHARED))
>> >+ if (!vma_test(vma, VMA_SHARED_BIT))
>> > return can_change_private_pte_writable(vma, addr, pte);
>> >
>> > return can_change_shared_pte_writable(vma, pte);
>> >@@ -194,7 +194,7 @@ static __always_inline void set_write_prot_commit_flush_ptes(struct vm_area_stru
>> > {
>> > bool set_write;
>> >
>> >- if (vma->vm_flags & VM_SHARED) {
>> >+ if (vma_test(vma, VMA_SHARED_BIT)) {
>> > set_write = can_change_shared_pte_writable(vma, ptent);
>> > prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes,
>> > /* idx = */ 0, set_write, tlb);
>> >@@ -811,8 +811,8 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
>> > vm_unacct_memory(nrpages);
>> >
>> > /*
>> >- * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
>> >- * fault on access.
>> >+ * Private VMA_LOCKED_BIT VMA becoming writable: trigger COW to avoid
>> >+ * major fault on access.
>> > */
>> > if (vma_flags_test(&new_vma_flags, VMA_WRITE_BIT) &&
>> > vma_flags_test(&old_vma_flags, VMA_LOCKED_BIT) &&
>> >@@ -886,7 +886,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>> > goto out;
>> > start = vma->vm_start;
>> > error = -EINVAL;
>> >- if (!(vma->vm_flags & VM_GROWSDOWN))
>> >+ if (!vma_test(vma, VMA_GROWSDOWN_BIT))
>> > goto out;
>> > } else {
>> > if (vma->vm_start > start)
>> >@@ -894,7 +894,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>> > if (unlikely(grows & PROT_GROWSUP)) {
>> > end = vma->vm_end;
>> > error = -EINVAL;
>> >- if (!(vma->vm_flags & VM_GROWSUP))
>> >+ if (!vma_test(vma, VMA_GROWSUP_BIT))
>>
>> IIUC, should this be
>>
>> if (!vma_test_single_mask(vma, VMA_GROWSUP))
>>
>> instead?
>>
>> #elif defined(CONFIG_PARISC)
>> #define VM_GROWSUP INIT_VM_FLAG(GROWSUP)
>> ...
>> #ifndef VM_GROWSUP
>> #define VM_GROWSUP VM_NONE
>> ...
>>
>> VM_GROWSUP is only defined as GROWSUP on parisc and becomes VM_NONE
>> elsewhere. But VMA_GROWSUP_BIT is the raw ARCH_1 bit, which is also used
>> for other arch-specific VMA flags:
>>
>> DECLARE_VMA_BIT_ALIAS(SAO, ARCH_1), /* Strong Access Ordering (powerpc) */
>> DECLARE_VMA_BIT_ALIAS(GROWSUP, ARCH_1), /* parisc */
>> DECLARE_VMA_BIT_ALIAS(SPARC_ADI, ARCH_1), /* sparc64 */
>> DECLARE_VMA_BIT_ALIAS(ARM64_BTI, ARCH_1), /* arm64 */
>> DECLARE_VMA_BIT_ALIAS(ARCH_CLEAR, ARCH_1), /* sparc64, arm64 */
>> DECLARE_VMA_BIT_ALIAS(MAPPED_COPY, ARCH_1), /* !CONFIG_MMU */
>>
>> Other vma_test() changes look fine to me: just fixed INIT_VM_FLAG()
>> masks matching their VMA_*_BIT :)
>
> Thanks you're right, will fix!
>
> Again I swear I ran claude on all of this so it's failing me here :)
>
Is it better to add something like below to avoid misuse these mutually
exclusive bit aliases?
An example for VMA_GROWSUP_BIT:
#if defined(CONFIG_PARISC)
DECLARE_VMA_BIT_ALIAS(GROWSUP, ARCH_1), /* parisc */
#else
/* make VMA_GROWSUP_BIT a build bug on */
#endif
Hmm, these VMA_*_BIT are enum items, so the above might not be possible.
An alternative is to only define them for the corresponding config and
you will get build errors when trying to use them directly and the
config is not enabled. Otherwise, misuses like "vma_test(vma,
VMA_GROWSUP_BIT)" is harder to uncover.
--
Best Regards,
Yan, Zi
^ permalink raw reply
* Re: [patch 02/18] randomize_kstack: Provide add_random_kstack_offset_irqsoff()
From: Jinjie Ruan @ 2026-07-09 2:13 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Kees Cook, Michael Ellerman, Shrikanth Hegde,
linuxppc-dev, Huacai Chen, loongarch, Paul Walmsley,
Palmer Dabbelt, linux-riscv, Sven Schnelle, linux-s390, x86,
Mark Rutland, Andy Lutomirski, Oleg Nesterov, Richard Henderson,
Russell King, Catalin Marinas, Guo Ren, Geert Uytterhoeven,
Thomas Bogendoerfer, Helge Deller, Yoshinori Sato,
Richard Weinberger, Chris Zankel, linux-arm-kernel, linux-alpha,
linux-csky, linux-m68k, linux-mips, linux-parisc, linux-sh,
linux-um, Arnd Bergmann, Vineet Gupta, Will Deacon, Brian Cain,
Michal Simek, Dinh Nguyen, David S. Miller, Andreas Larsson,
linux-snps-arc, linux-hexagon, linux-openrisc, sparclinux,
linux-arch, Michal Suchánek, Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.768842729@kernel.org>
On 7/8/2026 3:06 AM, Thomas Gleixner wrote:
> add_random_kstack_offset() uses get/put_cpu_var() which is pointless
> overhead when it is invoked from low level entry code with interrupts
> disabled.
>
> Provide a irqsoff() variant, which avoids that.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Kees Cook <kees@kernel.org>
> ---
> include/linux/randomize_kstack.h | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> --- a/include/linux/randomize_kstack.h
> +++ b/include/linux/randomize_kstack.h
> @@ -77,8 +77,27 @@ static __always_inline u32 get_kstack_of
> } \
> } while (0)
>
> +/**
> + * add_random_kstack_offset_irqsoff - Increase stack utilization by a random offset.
> + *
> + * This should be used in the syscall entry path after user registers have been
> + * stored to the stack. Interrupts must be still disabled.
> + */
> +#define add_random_kstack_offset_irqsoff() \
> +do { \
> + lockdep_assert_irqs_disabled(); \
> + if (static_branch_maybe(CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT, \
> + &randomize_kstack_offset)) { \
> + u32 offset = prandom_u32_state(raw_cpu_ptr(&kstack_rnd_state)); \
> + u8 *ptr = __kstack_alloca(KSTACK_OFFSET_MAX(offset)); \
> + /* Keep allocation even after "ptr" loses scope. */ \
> + asm volatile("" :: "r"(ptr) : "memory"); \
> + } \
> +} while (0)
Or can we avoid these repetitions and reuse the same code?
> +
> #else /* CONFIG_RANDOMIZE_KSTACK_OFFSET */
> #define add_random_kstack_offset() do { } while (0)
> +#define add_random_kstack_offset_irqsoff() do { } while (0)
> #endif /* CONFIG_RANDOMIZE_KSTACK_OFFSET */
>
> #endif
>
^ permalink raw reply
* Re: [patch 16/18] x86/entry: Get rid of the sys_ni_syscall() indirection
From: Jinjie Ruan @ 2026-07-09 2:03 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Andy Lutomirski, Oleg Nesterov, Richard Henderson, Russell King,
Catalin Marinas, Guo Ren, Geert Uytterhoeven, Thomas Bogendoerfer,
Helge Deller, Yoshinori Sato, Richard Weinberger, Chris Zankel,
linux-arm-kernel, linux-alpha, linux-csky, linux-m68k, linux-mips,
linux-parisc, linux-sh, linux-um, Arnd Bergmann, Vineet Gupta,
Will Deacon, Brian Cain, Michal Simek, Dinh Nguyen,
David S. Miller, Andreas Larsson, linux-snps-arc, linux-hexagon,
linux-openrisc, sparclinux, linux-arch, Michal Suchánek,
Jonathan Corbet, linux-doc
In-Reply-To: <20260707190254.493733289@kernel.org>
On 7/8/2026 3:07 AM, Thomas Gleixner wrote:
> Invoking sys_ni_syscall() from a code path, which already knows that the
> syscall number is invalid just to assign -ENOSYS to regs->ax is a pointless
> exercise. It's even redundant as the low level entry code already has set
> regs->ax to -ENOSYS on entry.
Makes sense, the all reltaed entry has already initialized
regs->ax to -ENOSYS.
This makes the code very concise.
LGTM
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
>
> Remove the extra conditionals and the function calls.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> ---
> arch/x86/entry/syscall_32.c | 2 --
> arch/x86/entry/syscall_64.c | 10 +++-------
> 2 files changed, 3 insertions(+), 9 deletions(-)
>
> --- a/arch/x86/entry/syscall_32.c
> +++ b/arch/x86/entry/syscall_32.c
> @@ -81,8 +81,6 @@ static __always_inline void do_syscall_3
> if (likely(unr < IA32_NR_syscalls)) {
> unr = array_index_nospec(unr, IA32_NR_syscalls);
> regs->ax = ia32_sys_call(regs, unr);
> - } else if (nr != -1) {
> - regs->ax = __ia32_sys_ni_syscall(regs);
> }
> }
>
> --- a/arch/x86/entry/syscall_64.c
> +++ b/arch/x86/entry/syscall_64.c
> @@ -68,7 +68,7 @@ static __always_inline bool do_syscall_x
> return false;
> }
>
> -static __always_inline bool do_syscall_x32(struct pt_regs *regs, int nr)
> +static __always_inline void do_syscall_x32(struct pt_regs *regs, int nr)
> {
> /*
> * Adjust the starting offset of the table, and convert numbers
> @@ -80,9 +80,7 @@ static __always_inline bool do_syscall_x
> if (IS_ENABLED(CONFIG_X86_X32_ABI) && likely(xnr < X32_NR_syscalls)) {
> xnr = array_index_nospec(xnr, X32_NR_syscalls);
> regs->ax = x32_sys_call(regs, xnr);
> - return true;
> }
> - return false;
> }
>
> /* Returns true to return using SYSRET, or false to use IRET */
> @@ -92,10 +90,8 @@ static __always_inline bool do_syscall_x
>
> instrumentation_begin();
>
> - if (!do_syscall_x64(regs, nr) && !do_syscall_x32(regs, nr) && nr != -1) {
> - /* Invalid system call, but still a system call. */
> - regs->ax = __x64_sys_ni_syscall(regs);
> - }
> + if (!do_syscall_x64(regs, nr))
> + do_syscall_x32(regs, nr);
>
> instrumentation_end();
> syscall_exit_to_user_mode(regs);
>
^ permalink raw reply
* [PATCH 5/5] bitmap: Return size when no zero area is found
From: Yury Norov @ 2026-07-09 2:03 UTC (permalink / raw)
To: Russell King, Christophe Leroy (CS GROUP), David S. Miller,
Matthew Wilcox (Oracle), Andrew Morton, Andrzej Hajda,
Danilo Krummrich, Douglas Anderson, Herbert Xu, Jason Gunthorpe,
John Allen, Kees Cook, Leon Romanovsky, Madhavan Srinivasan,
Marek Szyprowski, Mauro Carvalho Chehab, Michael Ellerman,
Nicholas Piggin, Rasmus Villemoes, Tom Lendacky, Yury Norov,
linux-arm-kernel, linux-crypto, linux-kernel, linux-media,
linuxppc-dev
Cc: Yury Norov, sunyi
In-Reply-To: <20260709020312.133977-1-ynorov@nvidia.com>
Return the bitmap size, rather than size + 1, when
bitmap_find_next_zero_area_off() cannot find a suitable area. This
matches the conventional find_bit() failure sentinel and still lets
callers detect failure with an out-of-range check.
Document the public failure contract as a value greater than or equal
to the bitmap size, without requiring callers to depend on the exact
sentinel.
Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
include/linux/bitmap.h | 3 +++
lib/bitmap.c | 10 ++++------
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 8854acf77869..33f175a30304 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -209,6 +209,9 @@ unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
* The @align_mask should be one less than a power of 2; the effect is that
* the bit offset of all zero areas this function finds is multiples of that
* power of 2. A @align_mask of 0 means no alignment is required.
+ *
+ * Return: The bit offset of the found area or a value >= @size
+ * if no area is found.
*/
static __always_inline
unsigned long bitmap_find_next_zero_area(unsigned long *map,
diff --git a/lib/bitmap.c b/lib/bitmap.c
index b464d843f4eb..ed685127a107 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -424,6 +424,9 @@ EXPORT_SYMBOL(__bitmap_clear);
* The @align_mask should be one less than a power of 2; the effect is that
* the bit offset of all zero areas this function finds plus @align_offset
* is multiple of that power of 2.
+ *
+ * Return: The bit offset of the found area or a value greater than or equal
+ * to @size if no area is found.
*/
unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
unsigned long size,
@@ -448,12 +451,7 @@ unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
start = i;
}
- /*
- * Here, returning size + 1 is to maintain consistency
- * with the old version, where the return value is always
- * greater than size when no zero areas are found.
- */
- return size + 1;
+ return size;
}
EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
--
2.53.0
^ permalink raw reply related
* [PATCH 2/5] powerpc/msi: Treat bitmap size as allocation failure
From: Yury Norov @ 2026-07-09 2:03 UTC (permalink / raw)
To: Madhavan Srinivasan, Michael Ellerman, Nicholas Piggin,
Christophe Leroy (CS GROUP), linuxppc-dev, linux-kernel
Cc: Yury Norov
In-Reply-To: <20260709020312.133977-1-ynorov@nvidia.com>
bitmap_find_next_zero_area() uses an out-of-range return value to
indicate failure. Check for values greater than or equal to the bitmap
size so the caller does not depend on the exact failure sentinel.
Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
arch/powerpc/sysdev/msi_bitmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/sysdev/msi_bitmap.c b/arch/powerpc/sysdev/msi_bitmap.c
index 456a4f64ae0a..2f38d4b41ad3 100644
--- a/arch/powerpc/sysdev/msi_bitmap.c
+++ b/arch/powerpc/sysdev/msi_bitmap.c
@@ -21,7 +21,7 @@ int msi_bitmap_alloc_hwirqs(struct msi_bitmap *bmp, int num)
offset = bitmap_find_next_zero_area(bmp->bitmap, bmp->irq_count, 0,
num, (1 << order) - 1);
- if (offset > bmp->irq_count)
+ if (offset >= bmp->irq_count)
goto err;
bitmap_set(bmp->bitmap, offset, num);
--
2.53.0
^ permalink raw reply related
* [PATCH 0/5] bitmap: align bitmap_find_next_zero_area_off() output with the rest of the API
From: Yury Norov @ 2026-07-09 2:03 UTC (permalink / raw)
To: Russell King, Christophe Leroy (CS GROUP), David S. Miller,
Matthew Wilcox (Oracle), Andrew Morton, Andrzej Hajda,
Danilo Krummrich, Douglas Anderson, Herbert Xu, Jason Gunthorpe,
John Allen, Kees Cook, Leon Romanovsky, Madhavan Srinivasan,
Marek Szyprowski, Mauro Carvalho Chehab, Michael Ellerman,
Nicholas Piggin, Rasmus Villemoes, Tom Lendacky, Yury Norov,
linux-arm-kernel, linux-crypto, linux-kernel, linux-media,
linuxppc-dev
Cc: Yury Norov, sunyi
Bitmap search functions return a value greater than or equal to nbits when
no suitable bits are found. bitmap_find_next_zero_area_off() is an
exception: it returns a value greater than nbits.
Align the function with the rest of the API and adjust the affected callers
accordingly.
Patches 1-4 are sent only to their respective maintainers and mailing
lists. Patch 5 and the cover letter are sent to all recipients.
On top of -next. I plan to carry the series with bitmap-for-next.
Yury Norov (5):
ARM: dma-mapping: Treat bitmap size as allocation failure
powerpc/msi: Treat bitmap size as allocation failure
crypto: ccp: Treat bitmap size as allocation failure
media: s5p-mfc: Treat bitmap size as allocation failure
bitmap: Return size when no zero area is found
arch/arm/mm/dma-mapping.c | 4 ++--
arch/powerpc/sysdev/msi_bitmap.c | 2 +-
drivers/crypto/ccp/ccp-dev-v3.c | 2 +-
drivers/crypto/ccp/ccp-dev-v5.c | 6 +++---
drivers/media/platform/samsung/s5p-mfc/s5p_mfc_opr.c | 2 +-
include/linux/bitmap.h | 3 +++
lib/bitmap.c | 10 ++++------
7 files changed, 15 insertions(+), 14 deletions(-)
--
2.53.0
^ permalink raw reply
* Re: [PATCH 11/13] mm/mlock: convert mlock code to use vma_flags_t
From: Zi Yan @ 2026-07-09 2:01 UTC (permalink / raw)
To: Lorenzo Stoakes, Andrew Morton
Cc: Thomas Bogendoerfer, Madhavan Srinivasan, Michael Ellerman,
Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter, Lucas Stach, Inki Dae, Seung-Woo Kim,
Kyungmin Park, Krzysztof Kozlowski, Peter Griffin, Jani Nikula,
Joonas Lahtinen, Rodrigo Vivi, Tvrtko Ursulin, Rob Clark,
Dmitry Baryshkov, Lyude Paul, Danilo Krummrich, Tomi Valkeinen,
Sandy Huang, Heiko Stübner, Andy Yan, Thierry Reding,
Mikko Perttunen, Jonathan Hunter, Gerd Hoffmann, Dmitry Osipenko,
Zack Rusin, Matthew Brost, Thomas Hellstrom,
Oleksandr Andrushchenko, Helge Deller, Benjamin LaHaise,
Alexander Viro, Christian Brauner, Muchun Song, Oscar Salvador,
David Hildenbrand, Baolin Wang, Liam R . Howlett, Nico Pache,
Ryan Roberts, Dev Jain, Barry Song, Lance Yang, Hugh Dickins,
Vlastimil Babka, Mike Rapoport, Suren Baghdasaryan, Michal Hocko,
Jann Horn, Pedro Falcato, Kees Cook, Jaroslav Kysela,
Takashi Iwai, linux-mips, linux-kernel, linuxppc-dev, dri-devel,
etnaviv, linux-arm-kernel, linux-samsung-soc, intel-gfx,
linux-arm-msm, freedreno, nouveau, linux-rockchip, linux-tegra,
virtualization, intel-xe, xen-devel, linux-fbdev, linux-aio,
linux-fsdevel, linux-mm, linux-sound
In-Reply-To: <2db16db81538355ca65f778c246d2381c673cad4.1782760670.git.ljs@kernel.org>
On Mon Jun 29, 2026 at 3:25 PM EDT, Lorenzo Stoakes wrote:
> Replace use of the legacy vm_flags_t flags with vma_flags_t values
> throughout the mlock logic.
>
> Additionally update comments to reflect the changes to be consistent.
>
> No functional change intended.
>
> Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
> ---
> mm/mlock.c | 86 +++++++++++++++++++++++++++++-------------------------
> 1 file changed, 46 insertions(+), 40 deletions(-)
>
LGTM. What confused me when I was reading the code is VMA_LOCKED_MASK
and VMA_LOCKED_BIT, since both share the same prefix VMA_LOCKED. Before
looking at the definition of VMA_LOCKED_MASK, I was wondering when to
use _BIT or _MASK. But it is just a naming thing.
Anyway,
Reviewed-by: Zi Yan <ziy@nvidia.com>
--
Best Regards,
Yan, Zi
^ permalink raw reply
* Re: [PATCH 10/13] mm/vma: convert miscellaneous uses of VMA flags in core mm
From: Zi Yan @ 2026-07-09 1:52 UTC (permalink / raw)
To: Lorenzo Stoakes, Lance Yang
Cc: akpm, tsbogend, maddy, mpe, maarten.lankhorst, mripard,
tzimmermann, airlied, simona, l.stach, inki.dae, sw0312.kim,
kyungmin.park, krzk, peter.griffin, jani.nikula, joonas.lahtinen,
rodrigo.vivi, tursulin, robin.clark, lumag, lyude, dakr,
tomi.valkeinen, hjc, heiko, andy.yan, thierry.reding, mperttunen,
jonathanh, kraxel, dmitry.osipenko, zack.rusin, matthew.brost,
thomas.hellstrom, oleksandr_andrushchenko, deller, bcrl, viro,
brauner, muchun.song, osalvador, david, baolin.wang, liam, npache,
ryan.roberts, dev.jain, baohua, hughd, vbabka, rppt, surenb,
mhocko, jannh, pfalcato, kees, perex, tiwai, linux-mips,
linux-kernel, linuxppc-dev, dri-devel, etnaviv, linux-arm-kernel,
linux-samsung-soc, intel-gfx, linux-arm-msm, freedreno, nouveau,
linux-rockchip, linux-tegra, virtualization, intel-xe, xen-devel,
linux-fbdev, linux-aio, linux-fsdevel, linux-mm, linux-sound
In-Reply-To: <akaGxiTaJreEQn8T@lucifer>
On Thu Jul 2, 2026 at 11:46 AM EDT, Lorenzo Stoakes wrote:
> On Thu, Jul 02, 2026 at 09:12:33PM +0800, Lance Yang wrote:
>>
>> On Mon, Jun 29, 2026 at 08:25:33PM +0100, Lorenzo Stoakes wrote:
>> >Update various uses of legacy flags in vma.c and mmap.c to the new
>> >vma_flags_t type, updating comments alongside them to be consistent.
>> >
>> >Also update __install_special_mapping() to rearrange things slightly to
>> >accommodate the changes.
>> >
>> >Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
>> >---
>> [...]
>> >diff --git a/mm/vma.c b/mm/vma.c
>> >index b81c05e67a61..ab2ef0f04420 100644
>> >--- a/mm/vma.c
>> >+++ b/mm/vma.c
>> >@@ -3417,23 +3417,27 @@ struct vm_area_struct *__install_special_mapping(
>> > vm_flags_t vm_flags, void *priv,
>> > const struct vm_operations_struct *ops)
>> > {
>> >- int ret;
>> >+ vma_flags_t vma_flags = legacy_to_vma_flags(vm_flags);
>> > struct vm_area_struct *vma;
>> >+ int ret;
>> >
>> > vma = vm_area_alloc(mm);
>> >- if (unlikely(vma == NULL))
>> >+ if (unlikely(!vma))
>> > return ERR_PTR(-ENOMEM);
>> >
>> >- vma_set_range(vma, addr, addr + len, 0);
>> >- vm_flags |= vma_flags_to_legacy(mm->def_vma_flags) | VM_DONTEXPAND;
>> >+ vma_flags_set_mask(&vma_flags, mm->def_vma_flags);
>> >+ vma_flags_set(&vma_flags, VMA_DONTEXPAND_BIT);
>> > if (pgtable_supports_soft_dirty())
>> >- vm_flags |= VM_SOFTDIRTY;
>> >- vm_flags_init(vma, vm_flags & ~VM_LOCKED_MASK);
>> >+ vma_flags_set(&vma_flags, VMA_SOFTDIRTY_BIT);
>> >+ vma_flags_clear_mask(&vma_flags, VMA_LOCKED_MASK);
>> >+ vma->flags = vma_flags;
>>
>> Maybe worth a vma_flags_init() helper here to mirror vm_flags_init()?
>> With this open-coded, we lose the soft-dirty WARN_ON_ONCE sanity check.
>>
>> Might be nicer to keep that check in one place ;)
>
> I really hate all the VMA flag accessors, they conflate things horribly - we
> should be explicitly taking VMA write locks when we need to (and often killable
> ones actually) not assuming that a VMA flags accessor does (they should at most
> assert).
>
> This case is even more terribly egregious - you are setting flags at an
> arbitrary time, why are we asserting something about softdirty?
>
> You may update them as part of initialisation, maybe not. It's far from a
> guarantee and feels like a lazy place to put it.
>
> BUT obviously it's an oversight not to open code that here, so I'll update the
> patch to do that!
What do you want to open code here? softdirty WARN_ON_ONCE()?
vma_flags gets VMA_SOFTDIRTY_BIT just above vma->flags, why do we need a
check after that?
BTW, if you think the check is needed, patch 9 will need to be updated,
since the same pattern appears in create_init_stack_vma().
>
> I want VMA flags to be a clean stateless thing, other than the flags
> themselves. Implicit, unrelated, asserts or lock acquisitions in general should
> be done separately IMO.
>
Anyway,
Reviewed-by: Zi Yan <ziy@nvidia.com>
--
Best Regards,
Yan, Zi
^ permalink raw reply
* Re: [patch 15/18] x86/entry: Make syscall functions static
From: Jinjie Ruan @ 2026-07-09 1:47 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Andy Lutomirski, Oleg Nesterov, Richard Henderson, Russell King,
Catalin Marinas, Guo Ren, Geert Uytterhoeven, Thomas Bogendoerfer,
Helge Deller, Yoshinori Sato, Richard Weinberger, Chris Zankel,
linux-arm-kernel, linux-alpha, linux-csky, linux-m68k, linux-mips,
linux-parisc, linux-sh, linux-um, Arnd Bergmann, Vineet Gupta,
Will Deacon, Brian Cain, Michal Simek, Dinh Nguyen,
David S. Miller, Andreas Larsson, linux-snps-arc, linux-hexagon,
linux-openrisc, sparclinux, linux-arch, Michal Suchánek,
Jonathan Corbet, linux-doc
In-Reply-To: <20260707190254.438361565@kernel.org>
On 7/8/2026 3:06 AM, Thomas Gleixner wrote:
> They are only used in the respective source files. No point in exposing
> them.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> ---
> arch/x86/entry/syscall_32.c | 2 +-
> arch/x86/entry/syscall_64.c | 10 ++++++----
> arch/x86/include/asm/syscall.h | 8 --------
> 3 files changed, 7 insertions(+), 13 deletions(-)
>
> --- a/arch/x86/entry/syscall_32.c
> +++ b/arch/x86/entry/syscall_32.c
> @@ -41,7 +41,7 @@ const sys_call_ptr_t sys_call_table[] =
> #endif
>
> #define __SYSCALL(nr, sym) case nr: return __ia32_##sym(regs);
> -long ia32_sys_call(const struct pt_regs *regs, unsigned int nr)
> +static noinline long ia32_sys_call(const struct pt_regs *regs, unsigned int nr)
> {
> switch (nr) {
> #include <asm/syscalls_32.h>
> --- a/arch/x86/entry/syscall_64.c
> +++ b/arch/x86/entry/syscall_64.c
> @@ -32,7 +32,7 @@ const sys_call_ptr_t sys_call_table[] =
> #undef __SYSCALL
>
> #define __SYSCALL(nr, sym) case nr: return __x64_##sym(regs);
> -long x64_sys_call(const struct pt_regs *regs, unsigned int nr)
> +static noinline long x64_sys_call(const struct pt_regs *regs, unsigned int nr)
> {
> switch (nr) {
> #include <asm/syscalls_64.h>
> @@ -40,15 +40,17 @@ long x64_sys_call(const struct pt_regs *
> }
> }
>
> -#ifdef CONFIG_X86_X32_ABI
> -long x32_sys_call(const struct pt_regs *regs, unsigned int nr)
> +static noinline long x32_sys_call(const struct pt_regs *regs, unsigned int nr)
> {
> +#ifdef CONFIG_X86_X32_ABI
> switch (nr) {
> #include <asm/syscalls_x32.h>
> default: return __x64_sys_ni_syscall(regs);
> }
> -}
> +#else
> + return -ENOSYS;
> #endif
> +}
>
> static __always_inline bool do_syscall_x64(struct pt_regs *regs, int nr)
> {
> --- a/arch/x86/include/asm/syscall.h
> +++ b/arch/x86/include/asm/syscall.h
> @@ -21,14 +21,6 @@ typedef long (*sys_call_ptr_t)(const str
> extern const sys_call_ptr_t sys_call_table[];
>
> /*
> - * These may not exist, but still put the prototypes in so we
> - * can use IS_ENABLED().
> - */
> -extern long ia32_sys_call(const struct pt_regs *, unsigned int nr);
> -extern long x32_sys_call(const struct pt_regs *, unsigned int nr);
> -extern long x64_sys_call(const struct pt_regs *, unsigned int nr);
> -
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
> -/*
> * Only the low 32 bits of orig_ax are meaningful, so we return int.
> * This importantly ignores the high bits on 64-bit, so comparisons
> * sign-extend the low 32 bits.
>
^ permalink raw reply
* Re: [PATCH 09/13] mm/vma: update create_init_stack_vma() to use vma_flags_t
From: Zi Yan @ 2026-07-09 1:42 UTC (permalink / raw)
To: Lorenzo Stoakes, Andrew Morton
Cc: Thomas Bogendoerfer, Madhavan Srinivasan, Michael Ellerman,
Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter, Lucas Stach, Inki Dae, Seung-Woo Kim,
Kyungmin Park, Krzysztof Kozlowski, Peter Griffin, Jani Nikula,
Joonas Lahtinen, Rodrigo Vivi, Tvrtko Ursulin, Rob Clark,
Dmitry Baryshkov, Lyude Paul, Danilo Krummrich, Tomi Valkeinen,
Sandy Huang, Heiko Stübner, Andy Yan, Thierry Reding,
Mikko Perttunen, Jonathan Hunter, Gerd Hoffmann, Dmitry Osipenko,
Zack Rusin, Matthew Brost, Thomas Hellstrom,
Oleksandr Andrushchenko, Helge Deller, Benjamin LaHaise,
Alexander Viro, Christian Brauner, Muchun Song, Oscar Salvador,
David Hildenbrand, Baolin Wang, Liam R . Howlett, Nico Pache,
Ryan Roberts, Dev Jain, Barry Song, Lance Yang, Hugh Dickins,
Vlastimil Babka, Mike Rapoport, Suren Baghdasaryan, Michal Hocko,
Jann Horn, Pedro Falcato, Kees Cook, Jaroslav Kysela,
Takashi Iwai, linux-mips, linux-kernel, linuxppc-dev, dri-devel,
etnaviv, linux-arm-kernel, linux-samsung-soc, intel-gfx,
linux-arm-msm, freedreno, nouveau, linux-rockchip, linux-tegra,
virtualization, intel-xe, xen-devel, linux-fbdev, linux-aio,
linux-fsdevel, linux-mm, linux-sound
In-Reply-To: <34689784ee6856f100c02ad4eabeaa4db643713a.1782760670.git.ljs@kernel.org>
On Mon Jun 29, 2026 at 3:25 PM EDT, Lorenzo Stoakes wrote:
> Replace use of the legacy vm_flags_t flags with vma_flags_t values in
> create_init_stack_vma().
>
> As part of this change we add VMA_STACK_EARLY and VMA_STACK_INCOMPLETE
> vma_flags_t defines, and slightly rework create_init_stack_vma() for
> clarity.
>
> No functional change intended.
>
> Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
> ---
> include/linux/mm.h | 4 ++++
> mm/vma_exec.c | 18 +++++++++++-------
> 2 files changed, 15 insertions(+), 7 deletions(-)
>
LGTM.
Reviewed-by: Zi Yan <ziy@nvidia.com>
--
Best Regards,
Yan, Zi
^ permalink raw reply
* Re: [patch 12/18] ptrace, treewide: Rename ptrace_report_syscall_entry() to ptrace_report_syscall_permit_entry()
From: Jinjie Ruan @ 2026-07-09 1:41 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Arnd Bergmann, Oleg Nesterov, Richard Henderson,
Vineet Gupta, Russell King, Catalin Marinas, Will Deacon, Guo Ren,
Brian Cain, Geert Uytterhoeven, Michal Simek, Thomas Bogendoerfer,
Dinh Nguyen, Helge Deller, Yoshinori Sato, David S. Miller,
Andreas Larsson, Chris Zankel, linux-alpha, linux-snps-arc,
linux-arm-kernel, linux-csky, linux-hexagon, linux-m68k,
linux-mips, linux-openrisc, linux-parisc, linux-sh, sparclinux,
linux-um, linux-arch, Michael Ellerman, Shrikanth Hegde,
linuxppc-dev, Kees Cook, Huacai Chen, loongarch, Paul Walmsley,
Palmer Dabbelt, linux-riscv, Sven Schnelle, linux-s390, x86,
Mark Rutland, Andy Lutomirski, Richard Weinberger,
Michal Suchánek, Jonathan Corbet, linux-doc
In-Reply-To: <20260707190254.280015701@kernel.org>
On 7/8/2026 3:06 AM, Thomas Gleixner wrote:
> The return value of that function is boolean and tells the caller whether
> to permit the syscall processing or not.
>
> Rename the function so the purpose is clear and make the return type bool.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Cc: Richard Henderson <richard.henderson@linaro.org>
> Cc: Vineet Gupta <vgupta@kernel.org>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Guo Ren <guoren@kernel.org>
> Cc: Brian Cain <bcain@kernel.org>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: Michal Simek <monstr@monstr.eu>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Dinh Nguyen <dinguyen@kernel.org>
> Cc: Helge Deller <deller@gmx.de>
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Andreas Larsson <andreas@gaisler.com>
> Cc: Chris Zankel <chris@zankel.net>
> Cc: linux-alpha@vger.kernel.org
> Cc: linux-snps-arc@lists.infradead.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-csky@vger.kernel.org
> Cc: linux-hexagon@vger.kernel.org
> Cc: linux-m68k@lists.linux-m68k.org
> Cc: linux-mips@vger.kernel.org
> Cc: linux-openrisc@vger.kernel.org
> Cc: linux-parisc@vger.kernel.org
> Cc: linux-sh@vger.kernel.org
> Cc: sparclinux@vger.kernel.org
> Cc: linux-um@lists.infradead.org
> Cc: linux-arch@vger.kernel.org
> ---
> arch/alpha/kernel/ptrace.c | 2 +-
> arch/arc/kernel/ptrace.c | 2 +-
> arch/arm/kernel/ptrace.c | 2 +-
> arch/arm64/kernel/ptrace.c | 2 +-
> arch/csky/kernel/ptrace.c | 2 +-
> arch/hexagon/kernel/traps.c | 2 +-
> arch/m68k/kernel/ptrace.c | 2 +-
> arch/microblaze/kernel/ptrace.c | 2 +-
> arch/mips/kernel/ptrace.c | 2 +-
> arch/nios2/kernel/ptrace.c | 2 +-
> arch/openrisc/kernel/ptrace.c | 2 +-
> arch/parisc/kernel/ptrace.c | 10 ++++------
> arch/sh/kernel/ptrace_32.c | 2 +-
> arch/sparc/kernel/ptrace_32.c | 2 +-
> arch/sparc/kernel/ptrace_64.c | 2 +-
> arch/um/kernel/ptrace.c | 2 +-
> arch/xtensa/kernel/ptrace.c | 2 +-
> include/asm-generic/syscall.h | 4 ++--
> include/linux/entry-common.h | 25 ++++++++++++-------------
> include/linux/ptrace.h | 13 ++++++-------
> 20 files changed, 40 insertions(+), 44 deletions(-)
>
> --- a/arch/alpha/kernel/ptrace.c
> +++ b/arch/alpha/kernel/ptrace.c
> @@ -375,7 +375,7 @@ asmlinkage unsigned long syscall_trace_e
> struct pt_regs *regs = current_pt_regs();
>
> if (test_thread_flag(TIF_SYSCALL_TRACE) &&
> - ptrace_report_syscall_entry(regs)) {
> + !ptrace_report_syscall_permit_entry(regs)) {
> syscall_set_nr(current, regs, -1);
> if (regs->r19 == 0 && regs->r0 == (unsigned long)-1)
> syscall_set_return_value(current, regs, -ENOSYS, 0);
> --- a/arch/arc/kernel/ptrace.c
> +++ b/arch/arc/kernel/ptrace.c
> @@ -342,7 +342,7 @@ long arch_ptrace(struct task_struct *chi
> asmlinkage int syscall_trace_enter(struct pt_regs *regs)
> {
> if (test_thread_flag(TIF_SYSCALL_TRACE))
> - if (ptrace_report_syscall_entry(regs))
> + if (!ptrace_report_syscall_permit_entry(regs))
> return ULONG_MAX;
>
> #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
> --- a/arch/arm/kernel/ptrace.c
> +++ b/arch/arm/kernel/ptrace.c
> @@ -840,7 +840,7 @@ static void report_syscall(struct pt_reg
>
> if (dir == PTRACE_SYSCALL_EXIT)
> ptrace_report_syscall_exit(regs, 0);
> - else if (ptrace_report_syscall_entry(regs))
> + else if (!ptrace_report_syscall_permit_entry(regs))
> current_thread_info()->abi_syscall = -1;
>
> regs->ARM_ip = ip;
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -2379,7 +2379,7 @@ static int report_syscall_entry(struct p
> int regno, ret;
>
> saved_reg = ptrace_save_reg(regs, PTRACE_SYSCALL_ENTER, ®no);
> - ret = ptrace_report_syscall_entry(regs);
> + ret = !ptrace_report_syscall_permit_entry(regs);
> if (ret)
> forget_syscall(regs);
> regs->regs[regno] = saved_reg;
> --- a/arch/csky/kernel/ptrace.c
> +++ b/arch/csky/kernel/ptrace.c
> @@ -320,7 +320,7 @@ long arch_ptrace(struct task_struct *chi
> asmlinkage int syscall_trace_enter(struct pt_regs *regs)
> {
> if (test_thread_flag(TIF_SYSCALL_TRACE))
> - if (ptrace_report_syscall_entry(regs))
> + if (!ptrace_report_syscall_permit_entry(regs))
> return -1;
>
> if (!seccomp_permit_syscall())
> --- a/arch/hexagon/kernel/traps.c
> +++ b/arch/hexagon/kernel/traps.c
> @@ -345,7 +345,7 @@ void do_trap0(struct pt_regs *regs)
>
> /* allow strace to catch syscall args */
> if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE) &&
> - ptrace_report_syscall_entry(regs)))
> + !ptrace_report_syscall_permit_entry(regs)))
> return; /* return -ENOSYS somewhere? */
>
> /* Interrupts should be re-enabled for syscall processing */
> --- a/arch/m68k/kernel/ptrace.c
> +++ b/arch/m68k/kernel/ptrace.c
> @@ -279,7 +279,7 @@ asmlinkage int syscall_trace_enter(void)
> int ret = 0;
>
> if (test_thread_flag(TIF_SYSCALL_TRACE))
> - ret = ptrace_report_syscall_entry(task_pt_regs(current));
> + ret = !ptrace_report_syscall_permit_entry(task_pt_regs(current));
>
> if (!seccomp_permit_syscall())
> return -1;
> --- a/arch/microblaze/kernel/ptrace.c
> +++ b/arch/microblaze/kernel/ptrace.c
> @@ -139,7 +139,7 @@ asmlinkage unsigned long do_syscall_trac
> secure_computing_strict(regs->r12);
>
> if (test_thread_flag(TIF_SYSCALL_TRACE) &&
> - ptrace_report_syscall_entry(regs))
> + !ptrace_report_syscall_permit_entry(regs))
> /*
> * Tracing decided this syscall should not happen.
> * We'll return a bogus call number to get an ENOSYS
> --- a/arch/mips/kernel/ptrace.c
> +++ b/arch/mips/kernel/ptrace.c
> @@ -1324,7 +1324,7 @@ asmlinkage long syscall_trace_enter(stru
> user_exit();
>
> if (test_thread_flag(TIF_SYSCALL_TRACE)) {
> - if (ptrace_report_syscall_entry(regs))
> + if (!ptrace_report_syscall_permit_entry(regs))
> return -1;
> }
>
> --- a/arch/nios2/kernel/ptrace.c
> +++ b/arch/nios2/kernel/ptrace.c
> @@ -133,7 +133,7 @@ asmlinkage int do_syscall_trace_enter(vo
> int ret = 0;
>
> if (test_thread_flag(TIF_SYSCALL_TRACE))
> - ret = ptrace_report_syscall_entry(task_pt_regs(current));
> + ret = !ptrace_report_syscall_permit_entry(task_pt_regs(current));
>
> return ret;
> }
> --- a/arch/openrisc/kernel/ptrace.c
> +++ b/arch/openrisc/kernel/ptrace.c
> @@ -293,7 +293,7 @@ asmlinkage long do_syscall_trace_enter(s
> long ret = 0;
>
> if (test_thread_flag(TIF_SYSCALL_TRACE) &&
> - ptrace_report_syscall_entry(regs))
> + !ptrace_report_syscall_permit_entry(regs))
> /*
> * Tracing decided this syscall should not happen.
> * We'll return a bogus call number to get an ENOSYS
> --- a/arch/parisc/kernel/ptrace.c
> +++ b/arch/parisc/kernel/ptrace.c
> @@ -326,7 +326,7 @@ long compat_arch_ptrace(struct task_stru
> long do_syscall_trace_enter(struct pt_regs *regs)
> {
> if (test_thread_flag(TIF_SYSCALL_TRACE)) {
> - int rc = ptrace_report_syscall_entry(regs);
> + bool permit = ptrace_report_syscall_permit_entry(regs);
>
> /*
> * As tracesys_next does not set %r28 to -ENOSYS
> @@ -334,12 +334,10 @@ long do_syscall_trace_enter(struct pt_re
> */
> regs->gr[28] = -ENOSYS;
>
> - if (rc) {
> + if (!permit) {
> /*
> - * A nonzero return code from
> - * ptrace_report_syscall_entry() tells us
> - * to prevent the syscall execution. Skip
> - * the syscall call and the syscall restart handling.
> + * Skip the syscall call and the syscall restart
> + * handling.
> *
> * Note that the tracer may also just change
> * regs->gr[20] to an invalid syscall number,
> --- a/arch/sh/kernel/ptrace_32.c
> +++ b/arch/sh/kernel/ptrace_32.c
> @@ -455,7 +455,7 @@ long arch_ptrace(struct task_struct *chi
> asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
> {
> if (test_thread_flag(TIF_SYSCALL_TRACE) &&
> - ptrace_report_syscall_entry(regs)) {
> + !ptrace_report_syscall_permit_entry(regs)) {
> regs->regs[0] = -ENOSYS;
> return -1;
> }
> --- a/arch/sparc/kernel/ptrace_32.c
> +++ b/arch/sparc/kernel/ptrace_32.c
> @@ -441,7 +441,7 @@ asmlinkage int syscall_trace(struct pt_r
> if (syscall_exit_p)
> ptrace_report_syscall_exit(regs, 0);
> else
> - ret = ptrace_report_syscall_entry(regs);
> + ret = !ptrace_report_syscall_permit_entry(regs);
> }
>
> return ret;
> --- a/arch/sparc/kernel/ptrace_64.c
> +++ b/arch/sparc/kernel/ptrace_64.c
> @@ -1093,7 +1093,7 @@ asmlinkage int syscall_trace_enter(struc
> user_exit();
>
> if (test_thread_flag(TIF_SYSCALL_TRACE))
> - ret = ptrace_report_syscall_entry(regs);
> + ret = !ptrace_report_syscall_permit_entry(regs);
>
> if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
> trace_sys_enter(regs, regs->u_regs[UREG_G1]);
> --- a/arch/um/kernel/ptrace.c
> +++ b/arch/um/kernel/ptrace.c
> @@ -135,7 +135,7 @@ int syscall_trace_enter(struct pt_regs *
> if (!test_thread_flag(TIF_SYSCALL_TRACE))
> return 0;
>
> - return ptrace_report_syscall_entry(regs);
> + return !ptrace_report_syscall_permit_entry(regs);
> }
>
> void syscall_trace_leave(struct pt_regs *regs)
> --- a/arch/xtensa/kernel/ptrace.c
> +++ b/arch/xtensa/kernel/ptrace.c
> @@ -547,7 +547,7 @@ int do_syscall_trace_enter(struct pt_reg
> regs->areg[2] = -ENOSYS;
>
> if (test_thread_flag(TIF_SYSCALL_TRACE) &&
> - ptrace_report_syscall_entry(regs)) {
> + !ptrace_report_syscall_permit_entry(regs)) {
> regs->areg[2] = -ENOSYS;
> regs->syscall = NO_SYSCALL;
> return 0;
> --- a/include/asm-generic/syscall.h
> +++ b/include/asm-generic/syscall.h
> @@ -58,8 +58,8 @@ void syscall_set_nr(struct task_struct *
> *
> * It's only valid to call this when @task is stopped for system
> * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or
> - * %SYSCALL_WORK_SYSCALL_AUDIT), after ptrace_report_syscall_entry()
> - * returned nonzero to prevent the system call from taking place.
> + * %SYSCALL_WORK_SYSCALL_AUDIT), after ptrace_report_syscall_permit_entry()
> + * returned False to prevent the system call from taking place.
> *
> * This rolls back the register state in @regs so it's as if the
> * system call instruction was a no-op. The registers containing
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -38,21 +38,22 @@
> SYSCALL_WORK_SYSCALL_EXIT_TRAP)
>
> /**
> - * arch_ptrace_report_syscall_entry - Architecture specific ptrace_report_syscall_entry() wrapper
> + * arch_ptrace_report_syscall_permit_entry - Architecture specific wrapper for
> + * ptrace_report_syscall_permit_entry()
> * @regs: Pointer to the register state at syscall entry
> *
> - * Invoked from syscall_trace_enter() to wrap ptrace_report_syscall_entry().
> + * Invoked from syscall_trace_enter() to wrap ptrace_report_syscall_permit_entry().
> *
> - * This allows architecture specific ptrace_report_syscall_entry()
> + * This allows architecture specific ptrace_report_syscall_permit_entry()
> * implementations. If not defined by the architecture this falls back to
> - * to ptrace_report_syscall_entry().
> + * to ptrace_report_syscall_permit_entry().
> */
> -static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs);
> +static __always_inline bool arch_ptrace_report_syscall_permit_entry(struct pt_regs *regs);
>
> -#ifndef arch_ptrace_report_syscall_entry
> -static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs)
> +#ifndef arch_ptrace_report_syscall_permit_entry
> +static __always_inline bool arch_ptrace_report_syscall_permit_entry(struct pt_regs *regs)
> {
> - return ptrace_report_syscall_entry(regs);
> + return ptrace_report_syscall_permit_entry(regs);
> }
> #endif
>
> @@ -73,8 +74,6 @@ static inline void syscall_enter_audit(s
> static __always_inline long syscall_trace_enter(struct pt_regs *regs, unsigned long work,
> long syscall)
> {
> - long ret = 0;
> -
> /*
> * Handle Syscall User Dispatch. This must comes first, since
> * the ABI here can be something that doesn't make sense for
> @@ -95,8 +94,8 @@ static __always_inline long syscall_trac
>
> /* Handle ptrace */
> if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
> - ret = arch_ptrace_report_syscall_entry(regs);
> - if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))
> + if (!arch_ptrace_report_syscall_permit_entry(regs) ||
> + (work & SYSCALL_WORK_SYSCALL_EMU))
> return -1L;
> }
>
> @@ -137,7 +136,7 @@ static __always_inline long syscall_trac
> * It handles the following work items:
> *
> * 1) syscall_work flag dependent invocations of
> - * ptrace_report_syscall_entry(), __seccomp_permit_syscall(), trace_sys_enter()
> + * ptrace_report_syscall_permit_entry(), __seccomp_permit_syscall(), trace_sys_enter()
> * 2) Invocation of audit_syscall_entry()
> */
> static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
> --- a/include/linux/ptrace.h
> +++ b/include/linux/ptrace.h
> @@ -405,13 +405,13 @@ extern void sigaction_compat_abi(struct
> /*
> * ptrace report for syscall entry and exit looks identical.
> */
> -static inline int ptrace_report_syscall(unsigned long message)
> +static inline bool ptrace_report_syscall(unsigned long message)
> {
> int ptrace = current->ptrace;
> int signr;
>
> if (!(ptrace & PT_PTRACED))
> - return 0;
> + return true;
>
> signr = ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0),
> message);
> @@ -424,11 +424,11 @@ static inline int ptrace_report_syscall(
> if (signr)
> send_sig(signr, current, 1);
>
> - return fatal_signal_pending(current);
> + return !fatal_signal_pending(current);
> }
>
> /**
> - * ptrace_report_syscall_entry - task is about to attempt a system call
> + * ptrace_report_syscall_permit_entry - task is about to attempt a system call
> * @regs: user register state of current task
> *
> * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
> @@ -438,7 +438,7 @@ static inline int ptrace_report_syscall(
> * call number and arguments to be tried. It is safe to block here,
> * preventing the system call from beginning.
> *
> - * Returns zero normally, or nonzero if the calling arch code should abort
> + * Returns True normally, or False if the calling architecture code should abort
> * the system call. That must prevent normal entry so no system call is
> * made. If @task ever returns to user mode after this, its register state
> * is unspecified, but should be something harmless like an %ENOSYS error
> @@ -447,8 +447,7 @@ static inline int ptrace_report_syscall(
> *
> * Called without locks, just after entering kernel mode.
> */
> -static inline __must_check int ptrace_report_syscall_entry(
> - struct pt_regs *regs)
> +static inline __must_check bool ptrace_report_syscall_permit_entry(struct pt_regs *regs)
> {
> return ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_ENTRY);
> }
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
>
^ permalink raw reply
* Re: [patch 01/18] powerpc: Move stack randomization after syscall_enter_from_user_mode()
From: Jinjie Ruan @ 2026-07-09 1:20 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Andy Lutomirski, Oleg Nesterov, Richard Henderson, Russell King,
Catalin Marinas, Guo Ren, Geert Uytterhoeven, Thomas Bogendoerfer,
Helge Deller, Yoshinori Sato, Richard Weinberger, Chris Zankel,
linux-arm-kernel, linux-alpha, linux-csky, linux-m68k, linux-mips,
linux-parisc, linux-sh, linux-um, Arnd Bergmann, Vineet Gupta,
Will Deacon, Brian Cain, Michal Simek, Dinh Nguyen,
David S. Miller, Andreas Larsson, linux-snps-arc, linux-hexagon,
linux-openrisc, sparclinux, linux-arch, Michal Suchánek,
Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.718191130@kernel.org>
On 7/8/2026 3:05 AM, Thomas Gleixner wrote:
> add_random_kstack_offset() is invoked before syscall_enter_from_user_mode()
> establishes state. That's wrong because add_random_kstack_offset() calls
> into instrumentable code.
>
> Move it after syscall_enter_from_user_mode() to ensure that state is
> correctly established.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
> Cc: linuxppc-dev@lists.ozlabs.org
> ---
> arch/powerpc/kernel/syscall.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/powerpc/kernel/syscall.c
> +++ b/arch/powerpc/kernel/syscall.c
> @@ -19,8 +19,8 @@ notrace long system_call_exception(struc
> long ret;
> syscall_fn f;
>
> - add_random_kstack_offset();
> r0 = syscall_enter_from_user_mode(regs, r0);
> + add_random_kstack_offset();
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
>
> if (unlikely(r0 >= NR_syscalls)) {
> if (unlikely(trap_is_unsupported_scv(regs))) {
>
^ permalink raw reply
* Re: [patch 10/18] entry: Use syscall number instead of rereading it
From: Radu Rendec @ 2026-07-08 21:39 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Jinjie Ruan, Andy Lutomirski, Oleg Nesterov, Richard Henderson,
Russell King, Catalin Marinas, Guo Ren, Geert Uytterhoeven,
Thomas Bogendoerfer, Helge Deller, Yoshinori Sato,
Richard Weinberger, Chris Zankel, linux-arm-kernel, linux-alpha,
linux-csky, linux-m68k, linux-mips, linux-parisc, linux-sh,
linux-um, Arnd Bergmann, Vineet Gupta, Will Deacon, Brian Cain,
Michal Simek, Dinh Nguyen, David S. Miller, Andreas Larsson,
linux-snps-arc, linux-hexagon, linux-openrisc, sparclinux,
linux-arch, Michal Suchánek, Jonathan Corbet, linux-doc
In-Reply-To: <20260707190254.181086755@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> rseq_syscall_enter_work() is invoked before the syscall number can be
> modified. So there is no point in rereading it from pt_regs.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> ---
> include/linux/entry-common.h | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -70,9 +70,10 @@ static inline void syscall_enter_audit(s
> }
> }
>
> -static __always_inline long syscall_trace_enter(struct pt_regs *regs, unsigned long work)
> +static __always_inline long syscall_trace_enter(struct pt_regs *regs, unsigned long work,
> + long syscall)
> {
> - long syscall, ret = 0;
> + long ret = 0;
>
> /*
> * Handle Syscall User Dispatch. This must comes first, since
> @@ -90,7 +91,7 @@ static __always_inline long syscall_trac
> * through hrtimer_interrupt().
> */
> if (work & SYSCALL_WORK_SYSCALL_RSEQ_SLICE)
> - rseq_syscall_enter_work(syscall_get_nr(current, regs));
> + rseq_syscall_enter_work(syscall);
>
> /* Handle ptrace */
> if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
> @@ -145,7 +146,7 @@ static __always_inline long syscall_ente
> unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
>
> if (work & SYSCALL_WORK_ENTER)
> - syscall = syscall_trace_enter(regs, work);
> + syscall = syscall_trace_enter(regs, work, syscall);
>
> return syscall;
> }
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
* Re: [patch 09/18] entry: Remove syscall_enter_from_user_mode()
From: Radu Rendec @ 2026-07-08 21:21 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Jinjie Ruan, Andy Lutomirski, Oleg Nesterov, Richard Henderson,
Russell King, Catalin Marinas, Guo Ren, Geert Uytterhoeven,
Thomas Bogendoerfer, Helge Deller, Yoshinori Sato,
Richard Weinberger, Chris Zankel, linux-arm-kernel, linux-alpha,
linux-csky, linux-m68k, linux-mips, linux-parisc, linux-sh,
linux-um, Arnd Bergmann, Vineet Gupta, Will Deacon, Brian Cain,
Michal Simek, Dinh Nguyen, David S. Miller, Andreas Larsson,
linux-snps-arc, linux-hexagon, linux-openrisc, sparclinux,
linux-arch, Michal Suchánek, Jonathan Corbet, linux-doc
In-Reply-To: <20260707190254.132654198@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> All architecture use either:
>
> nr = enter_from_user_mode_randomize_stack(regs, nr);
You probably mean syscall_enter_from_user_mode_randomize_stack.
>
> or
>
> enter_from_user_mode_randomize_stack(regs);
> nr = syscall_enter_from_user_mode_work(regs, nr);
>
> Remove the now unused function.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> ---
> Documentation/core-api/entry.rst | 17 +++++++++-------
> include/linux/entry-common.h | 40 +++------------------------------------
> include/linux/irq-entry-common.h | 6 ++---
> 3 files changed, 17 insertions(+), 46 deletions(-)
>
> --- a/Documentation/core-api/entry.rst
> +++ b/Documentation/core-api/entry.rst
> @@ -68,7 +68,7 @@ low-level C code must not be instrumente
> noinstr void syscall(struct pt_regs *regs, int nr)
> {
> arch_syscall_enter(regs);
> - nr = syscall_enter_from_user_mode(regs, nr);
> + nr = syscall_enter_from_user_mode_randomize_stack(regs, nr);
>
> instrumentation_begin();
> if (!invoke_syscall(regs, nr) && nr != -1)
> @@ -78,12 +78,14 @@ low-level C code must not be instrumente
> syscall_exit_to_user_mode(regs);
> }
>
> -syscall_enter_from_user_mode() first invokes enter_from_user_mode() which
> -establishes state in the following order:
> +syscall_enter_from_user_mode_randomize_stack() first invokes
> +enter_from_user_mode_randomize_stack() which establishes state in the
> +following order:
>
> * Lockdep
> * RCU / Context tracking
> * Tracing
> + * Apply stack randomization
>
> and then invokes the various entry work functions like ptrace, seccomp, audit,
> syscall tracing, etc. After all that is done, the instrumentable invoke_syscall
> @@ -99,10 +101,11 @@ that it invokes exit_to_user_mode() whic
> * RCU / Context tracking
> * Lockdep
>
> -syscall_enter_from_user_mode() and syscall_exit_to_user_mode() are also
> -available as fine grained subfunctions in cases where the architecture code
> -has to do extra work between the various steps. In such cases it has to
> -ensure that enter_from_user_mode() is called first on entry and
> +syscall_enter_from_user_mode_randomize_stack() and
> +syscall_exit_to_user_mode() are also available as fine grained subfunctions
> +in cases where the architecture code has to do extra work between the
> +various steps. In such cases it has to ensure that
> +enter_from_user_mode_randomize_stack() is called first on entry and
> exit_to_user_mode() is called last on exit.
>
> Do not nest syscalls. Nested syscalls will cause RCU and/or context tracking
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -19,7 +19,7 @@
> #endif
>
> /*
> - * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
> + * SYSCALL_WORK flags handled in syscall_enter_from_user_mode_work()
> */
> #define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
> SYSCALL_WORK_SYSCALL_TRACEPOINT | \
> @@ -205,42 +205,10 @@ do { \
> _ret; \
> })
>
> -/**
> - * syscall_enter_from_user_mode - Establish state and check and handle work
> - * before invoking a syscall
> - * @regs: Pointer to currents pt_regs
> - * @syscall: The syscall number
> - *
> - * Invoked from architecture specific syscall entry code with interrupts
> - * disabled. The calling code has to be non-instrumentable. When the
> - * function returns all state is correct, interrupts are enabled and the
> - * subsequent functions can be instrumented.
> - *
> - * This is the combination of enter_from_user_mode() and
> - * syscall_enter_from_user_mode_work() to be used when there is no
> - * architecture specific work to be done between the two.
> - *
> - * Returns: The original or a modified syscall number. See
> - * syscall_enter_from_user_mode_work() for further explanation.
> - */
> -static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
> -{
> - long ret;
> -
> - enter_from_user_mode(regs);
> -
> - instrumentation_begin();
> - local_irq_enable();
> - ret = syscall_enter_from_user_mode_work(regs, syscall);
> - instrumentation_end();
> -
> - return ret;
> -}
> -
> /*
> - * If SYSCALL_EMU is set, then the only reason to report is when
> - * SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall
> - * instruction has been already reported in syscall_enter_from_user_mode().
> + * If SYSCALL_EMU is set, then the only reason to report is when SINGLESTEP is
> + * set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall instruction has been
> + * already reported in syscall_enter_from_user_mode_work().
> */
> static __always_inline bool report_single_step(unsigned long work)
> {
> --- a/include/linux/irq-entry-common.h
> +++ b/include/linux/irq-entry-common.h
> @@ -49,9 +49,9 @@
> * Defaults to an empty implementation. Can be replaced by architecture
> * specific code.
> *
> - * Invoked from syscall_enter_from_user_mode() in the non-instrumentable
> - * section. Use __always_inline so the compiler cannot push it out of line
> - * and make it instrumentable.
> + * Invoked from enter_from_user_mode_syscall_and_randomize_stack() in the
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Probably syscall_enter_from_user_mode_randomize_stack()? But the
reality is it's only ever invoked from enter_from_user_mode(), which is
below in the same file (include/linux/irq-entry-common.h).
Granted, that's an always inline function, and it's used by both macros
you added (since the second one uses the first one).
> + * non-instrumentable section. Use __always_inline so the compiler cannot push
> + * it out of line and make it instrumentable.
> */
> static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs);
>
^ permalink raw reply
* Re: [patch 08/18] x86/syscall: Use [syscall_]enter_from_user_mode_randomize_stack()
From: Radu Rendec @ 2026-07-08 20:59 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, x86, Michael Ellerman, Shrikanth Hegde,
linuxppc-dev, Kees Cook, Huacai Chen, loongarch, Paul Walmsley,
Palmer Dabbelt, linux-riscv, Sven Schnelle, linux-s390,
Mark Rutland, Jinjie Ruan, Andy Lutomirski, Oleg Nesterov,
Richard Henderson, Russell King, Catalin Marinas, Guo Ren,
Geert Uytterhoeven, Thomas Bogendoerfer, Helge Deller,
Yoshinori Sato, Richard Weinberger, Chris Zankel,
linux-arm-kernel, linux-alpha, linux-csky, linux-m68k, linux-mips,
linux-parisc, linux-sh, linux-um, Arnd Bergmann, Vineet Gupta,
Will Deacon, Brian Cain, Michal Simek, Dinh Nguyen,
David S. Miller, Andreas Larsson, linux-snps-arc, linux-hexagon,
linux-openrisc, sparclinux, linux-arch, Michal Suchánek,
Jonathan Corbet, linux-doc
In-Reply-To: <20260707190254.079478122@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> These functions integrate the stack randomization.
>
> syscall_enter_from_user_mode_randomize_stack() has the advantage that the
> randomization happens early right after enter_from_user_mode().
>
> In both cases also the overhead of get/put_cpu_var() in
> add_random_kstack_offset() is avoided.
>
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: x86@kernel.org
> ---
> arch/x86/entry/syscall_32.c | 19 +++++--------------
> arch/x86/entry/syscall_64.c | 3 +--
> arch/x86/include/asm/entry-common.h | 1 -
> 3 files changed, 6 insertions(+), 17 deletions(-)
>
> --- 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
> * int80_is_external() below which calls into the APIC driver.
> * Identical for soft and external interrupts.
> */
> - enter_from_user_mode(regs);
> + enter_from_user_mode_randomize_stack(regs);
>
> instrumentation_begin();
> - add_random_kstack_offset();
>
> /* Validate that this is a soft interrupt to the extent possible */
> if (unlikely(int80_is_external()))
> @@ -210,11 +209,9 @@ DEFINE_FREDENTRY_RAW(int80_emulation)
> {
> int nr;
>
> - enter_from_user_mode(regs);
> + enter_from_user_mode_randomize_stack(regs);
>
> instrumentation_begin();
> - add_random_kstack_offset();
> -
> /*
> * FRED pushed 0 into regs::orig_ax and regs::ax contains the
> * syscall number.
> @@ -252,10 +249,10 @@ DEFINE_FREDENTRY_RAW(int80_emulation)
> * orig_ax, the int return value truncates it. This matches
> * the semantics of syscall_get_nr().
> */
> - nr = syscall_enter_from_user_mode(regs, nr);
> + nr = syscall_enter_from_user_mode_randomize_stack(regs, nr);
> +
> instrumentation_begin();
>
> - add_random_kstack_offset();
> do_syscall_32_irqs_on(regs, nr);
>
> instrumentation_end();
> @@ -268,15 +265,9 @@ static noinstr bool __do_fast_syscall_32
> int nr = syscall_32_enter(regs);
> int res;
>
> - /*
> - * 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);
>
> instrumentation_begin();
> - add_random_kstack_offset();
> local_irq_enable();
> /* Fetch EBP from where the vDSO stashed it. */
> 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
> /* Returns true to return using SYSRET, or false to use IRET */
> __visible noinstr bool do_syscall_64(struct pt_regs *regs, int nr)
> {
> - nr = syscall_enter_from_user_mode(regs, nr);
> + nr = syscall_enter_from_user_mode_randomize_stack(regs, nr);
>
> instrumentation_begin();
> - add_random_kstack_offset();
>
> if (!do_syscall_x64(regs, nr) && !do_syscall_x32(regs, nr) && nr != -1) {
> /* 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 @@
> #ifndef _ASM_X86_ENTRY_COMMON_H
> #define _ASM_X86_ENTRY_COMMON_H
>
> -#include <linux/randomize_kstack.h>
> #include <linux/user-return-notifier.h>
>
> #include <asm/nospec-branch.h>
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
* Re: [patch 07/18] s390/syscall: Use enter_from_user_mode_randomize_stack()
From: Radu Rendec @ 2026-07-08 20:57 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Sven Schnelle, linux-s390, Michael Ellerman,
Shrikanth Hegde, linuxppc-dev, Kees Cook, Huacai Chen, loongarch,
Paul Walmsley, Palmer Dabbelt, linux-riscv, x86, Mark Rutland,
Jinjie Ruan, Andy Lutomirski, Oleg Nesterov, Richard Henderson,
Russell King, Catalin Marinas, Guo Ren, Geert Uytterhoeven,
Thomas Bogendoerfer, Helge Deller, Yoshinori Sato,
Richard Weinberger, Chris Zankel, linux-arm-kernel, linux-alpha,
linux-csky, linux-m68k, linux-mips, linux-parisc, linux-sh,
linux-um, Arnd Bergmann, Vineet Gupta, Will Deacon, Brian Cain,
Michal Simek, Dinh Nguyen, David S. Miller, Andreas Larsson,
linux-snps-arc, linux-hexagon, linux-openrisc, sparclinux,
linux-arch, Michal Suchánek, Jonathan Corbet, linux-doc
In-Reply-To: <20260707190254.030598804@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> enter_from_user_mode_randomize_stack() replaces enter_from_user_mode() and
> the subsequent invocation of add_random_kstack_offset_irqsoff().
>
> As a bonus this avoids the overhead of get/put_cpu_var() in
> add_random_kstack_offset().
>
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Sven Schnelle <svens@linux.ibm.com>
> Cc: linux-s390@vger.kernel.org
> ---
> arch/s390/kernel/syscall.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> --- a/arch/s390/kernel/syscall.c
> +++ b/arch/s390/kernel/syscall.c
> @@ -97,8 +97,8 @@ void noinstr __do_syscall(struct pt_regs
> {
> unsigned long nr;
>
> - enter_from_user_mode(regs);
> - add_random_kstack_offset();
> + enter_from_user_mode_randomize_stack(regs);
> +
> regs->psw = get_lowcore()->svc_old_psw;
> regs->int_code = get_lowcore()->svc_int_code;
> update_timer_sys();
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
* Re: [patch 06/18] riscv/syscall: Use syscall_enter_from_user_mode_randomize_stack()
From: Radu Rendec @ 2026-07-08 20:57 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Paul Walmsley, Palmer Dabbelt, linux-riscv,
Michael Ellerman, Shrikanth Hegde, linuxppc-dev, Kees Cook,
Huacai Chen, loongarch, Sven Schnelle, linux-s390, x86,
Mark Rutland, Jinjie Ruan, Andy Lutomirski, Oleg Nesterov,
Richard Henderson, Russell King, Catalin Marinas, Guo Ren,
Geert Uytterhoeven, Thomas Bogendoerfer, Helge Deller,
Yoshinori Sato, Richard Weinberger, Chris Zankel,
linux-arm-kernel, linux-alpha, linux-csky, linux-m68k, linux-mips,
linux-parisc, linux-sh, linux-um, Arnd Bergmann, Vineet Gupta,
Will Deacon, Brian Cain, Michal Simek, Dinh Nguyen,
David S. Miller, Andreas Larsson, linux-snps-arc, linux-hexagon,
linux-openrisc, sparclinux, linux-arch, Michal Suchánek,
Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.974626922@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> syscall_enter_from_user_mode_randomize_stack() replaces
> syscall_enter_from_user_mode() and the subsequent invocation of
> add_random_kstack_offset().
>
> The advantage is that it applies the stack randomization right after
> enter_from_user_mode() and thereby avoids the overhead of get/put_cpu_var()
> as that code is invoked with interrupts disabled.
>
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Paul Walmsley <pjw@kernel.org>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: linux-riscv@lists.infradead.org
> ---
> arch/riscv/kernel/traps.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -7,7 +7,6 @@
> #include <linux/kernel.h>
> #include <linux/init.h>
> #include <linux/irqflags.h>
> -#include <linux/randomize_kstack.h>
> #include <linux/sched.h>
> #include <linux/sched/debug.h>
> #include <linux/sched/signal.h>
> @@ -333,9 +332,7 @@ void do_trap_ecall_u(struct pt_regs *reg
>
> riscv_v_vstate_discard(regs);
>
> - syscall = syscall_enter_from_user_mode(regs, syscall);
> -
> - add_random_kstack_offset();
> + syscall = syscall_enter_from_user_mode_randomize_stack(regs, syscall);
>
> if (syscall >= 0 && syscall < NR_syscalls) {
> syscall = array_index_nospec(syscall, NR_syscalls);
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
* Re: [patch 04/18] loongarch/syscall: Use syscall_enter_from_user_mode_randomize_stack()
From: Radu Rendec @ 2026-07-08 18:37 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Huacai Chen, loongarch, Michael Ellerman,
Shrikanth Hegde, linuxppc-dev, Kees Cook, Paul Walmsley,
Palmer Dabbelt, linux-riscv, Sven Schnelle, linux-s390, x86,
Mark Rutland, Jinjie Ruan, Andy Lutomirski, Oleg Nesterov,
Richard Henderson, Russell King, Catalin Marinas, Guo Ren,
Geert Uytterhoeven, Thomas Bogendoerfer, Helge Deller,
Yoshinori Sato, Richard Weinberger, Chris Zankel,
linux-arm-kernel, linux-alpha, linux-csky, linux-m68k, linux-mips,
linux-parisc, linux-sh, linux-um, Arnd Bergmann, Vineet Gupta,
Will Deacon, Brian Cain, Michal Simek, Dinh Nguyen,
David S. Miller, Andreas Larsson, linux-snps-arc, linux-hexagon,
linux-openrisc, sparclinux, linux-arch, Michal Suchánek,
Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.865955911@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> syscall_enter_from_user_mode_randomize_stack() replaces
> syscall_enter_from_user_mode() and the subsequent invocation of
> add_random_kstack_offset().
>
> The advantage is that it applies the stack randomization right after
> enter_from_user_mode() and thereby avoids the overhead of get/put_cpu_var()
> as that code is invoked with interrupts disabled.
>
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Huacai Chen <chenhuacai@kernel.org>
> Cc: loongarch@lists.linux.dev
> ---
> arch/loongarch/kernel/syscall.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> --- a/arch/loongarch/kernel/syscall.c
> +++ b/arch/loongarch/kernel/syscall.c
> @@ -11,7 +11,6 @@
> #include <linux/linkage.h>
> #include <linux/nospec.h>
> #include <linux/objtool.h>
> -#include <linux/randomize_kstack.h>
> #include <linux/syscalls.h>
> #include <linux/unistd.h>
>
> @@ -70,9 +69,7 @@ void noinstr __no_stack_protector do_sys
> regs->orig_a0 = regs->regs[4];
> regs->regs[4] = -ENOSYS;
>
> - nr = syscall_enter_from_user_mode(regs, nr);
> -
> - add_random_kstack_offset();
> + nr = syscall_enter_from_user_mode_randomize_stack(regs, nr);
>
> if (nr < NR_syscalls) {
> syscall_fn = sys_call_table[array_index_nospec(nr, NR_syscalls)];
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
* Re: [patch 05/18] powerpc/syscall: Use syscall_enter_from_user_mode_randomize_stack()
From: Radu Rendec @ 2026-07-08 18:35 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Jinjie Ruan, Andy Lutomirski, Oleg Nesterov, Richard Henderson,
Russell King, Catalin Marinas, Guo Ren, Geert Uytterhoeven,
Thomas Bogendoerfer, Helge Deller, Yoshinori Sato,
Richard Weinberger, Chris Zankel, linux-arm-kernel, linux-alpha,
linux-csky, linux-m68k, linux-mips, linux-parisc, linux-sh,
linux-um, Arnd Bergmann, Vineet Gupta, Will Deacon, Brian Cain,
Michal Simek, Dinh Nguyen, David S. Miller, Andreas Larsson,
linux-snps-arc, linux-hexagon, linux-openrisc, sparclinux,
linux-arch, Michal Suchánek, Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.918861529@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> syscall_enter_from_user_mode_randomize_stack() replaces
> syscall_enter_from_user_mode() and the subsequent invocation of
> add_random_kstack_offset().
>
> The advantage is that it applies the stack randomization right after
> enter_from_user_mode() and thereby avoids the overhead of get/put_cpu_var()
> as that code is invoked with interrupts disabled.
>
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
> Cc: linuxppc-dev@lists.ozlabs.org
> ---
> arch/powerpc/kernel/syscall.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> --- a/arch/powerpc/kernel/syscall.c
> +++ b/arch/powerpc/kernel/syscall.c
> @@ -2,7 +2,6 @@
>
> #include <linux/compat.h>
> #include <linux/context_tracking.h>
> -#include <linux/randomize_kstack.h>
> #include <linux/entry-common.h>
>
> #include <asm/interrupt.h>
> @@ -19,8 +18,7 @@ notrace long system_call_exception(struc
> long ret;
> syscall_fn f;
>
> - r0 = syscall_enter_from_user_mode(regs, r0);
> - add_random_kstack_offset();
> + r0 = syscall_enter_from_user_mode_randomize_stack(regs, r0);
>
> if (unlikely(r0 >= NR_syscalls)) {
> if (unlikely(trap_is_unsupported_scv(regs))) {
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
* Re: [PATCH 1/2] umh, treewide: Explicitly include linux/umh.h where needed
From: Michal Koutný @ 2026-07-08 18:13 UTC (permalink / raw)
To: Petr Pavlu
Cc: Tony Luck, Borislav Petkov, Thomas Gleixner, Ingo Molnar,
Dave Hansen, x86, H. Peter Anvin, Philipp Reisner, Lars Ellenberg,
Christoph Böhmwalder, Jens Axboe, Johan Hovold, Alex Elder,
Greg Kroah-Hartman, Rafael J. Wysocki, Michal Januszewski,
Helge Deller, Alexander Viro, Christian Brauner, Jan Kara,
Trond Myklebust, Anna Schumaker, Chuck Lever, Jeff Layton,
NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey, Mark Fasheh,
Joel Becker, Joseph Qi, Tejun Heo, Johannes Weiner,
Luis Chamberlain, Daniel Gomez, Sami Tolvanen, Aaron Tomlin,
Pavel Machek, Len Brown, Andrew Morton, Danilo Krummrich,
Nikolay Aleksandrov, Ido Schimmel, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Simon Horman, David Howells,
Jarkko Sakkinen, Paul Moore, James Morris, Serge E. Hallyn,
Kentaro Takeda, Tetsuo Handa, linux-edac, linux-kernel, drbd-dev,
linux-block, greybus-dev, linuxppc-dev, linux-acpi, linux-fbdev,
dri-devel, linux-fsdevel, linux-nfs, ocfs2-devel, cgroups,
linux-modules, linux-pm, driver-core, bridge, netdev, keyrings,
linux-security-module
In-Reply-To: <20260708154510.6794-2-petr.pavlu@suse.com>
[-- Attachment #1: Type: text/plain, Size: 583 bytes --]
Hi Petr.
On Wed, Jul 08, 2026 at 05:44:29PM +0200, Petr Pavlu <petr.pavlu@suse.com> wrote:
> diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
> index a4337c9b5287..60eb994c32ae 100644
> --- a/kernel/cgroup/cgroup-v1.c
> +++ b/kernel/cgroup/cgroup-v1.c
> @@ -16,6 +16,7 @@
> #include <linux/pid_namespace.h>
> #include <linux/cgroupstats.h>
> #include <linux/fs_parser.h>
> +#include <linux/umh.h>
>
> #include <trace/events/cgroup.h>
There is kmod.h in here too but it's unnecessary, no module lazy loading
in this code.
Thanks,
Michal
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 265 bytes --]
^ permalink raw reply
* Re: [patch 01/18] powerpc: Move stack randomization after syscall_enter_from_user_mode()
From: Radu Rendec @ 2026-07-08 17:22 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Jinjie Ruan, Andy Lutomirski, Oleg Nesterov, Richard Henderson,
Russell King, Catalin Marinas, Guo Ren, Geert Uytterhoeven,
Thomas Bogendoerfer, Helge Deller, Yoshinori Sato,
Richard Weinberger, Chris Zankel, linux-arm-kernel, linux-alpha,
linux-csky, linux-m68k, linux-mips, linux-parisc, linux-sh,
linux-um, Arnd Bergmann, Vineet Gupta, Will Deacon, Brian Cain,
Michal Simek, Dinh Nguyen, David S. Miller, Andreas Larsson,
linux-snps-arc, linux-hexagon, linux-openrisc, sparclinux,
linux-arch, Michal Suchánek, Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.718191130@kernel.org>
On Tue, 2026-07-07 at 21:05 +0200, Thomas Gleixner wrote:
> add_random_kstack_offset() is invoked before syscall_enter_from_user_mode()
> establishes state. That's wrong because add_random_kstack_offset() calls
> into instrumentable code.
>
> Move it after syscall_enter_from_user_mode() to ensure that state is
> correctly established.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
> Cc: linuxppc-dev@lists.ozlabs.org
> ---
> arch/powerpc/kernel/syscall.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/powerpc/kernel/syscall.c
> +++ b/arch/powerpc/kernel/syscall.c
> @@ -19,8 +19,8 @@ notrace long system_call_exception(struc
> long ret;
> syscall_fn f;
>
> - add_random_kstack_offset();
> r0 = syscall_enter_from_user_mode(regs, r0);
> + add_random_kstack_offset();
>
> if (unlikely(r0 >= NR_syscalls)) {
> if (unlikely(trap_is_unsupported_scv(regs))) {
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
* Re: [patch 03/18] entry: Provide [syscall_]enter_from_user_mode_randomize_stack()
From: Radu Rendec @ 2026-07-08 17:26 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Michael Ellerman, Shrikanth Hegde, linuxppc-dev,
Kees Cook, Huacai Chen, loongarch, Paul Walmsley, Palmer Dabbelt,
linux-riscv, Sven Schnelle, linux-s390, x86, Mark Rutland,
Jinjie Ruan, Andy Lutomirski, Oleg Nesterov, Richard Henderson,
Russell King, Catalin Marinas, Guo Ren, Geert Uytterhoeven,
Thomas Bogendoerfer, Helge Deller, Yoshinori Sato,
Richard Weinberger, Chris Zankel, linux-arm-kernel, linux-alpha,
linux-csky, linux-m68k, linux-mips, linux-parisc, linux-sh,
linux-um, Arnd Bergmann, Vineet Gupta, Will Deacon, Brian Cain,
Michal Simek, Dinh Nguyen, David S. Miller, Andreas Larsson,
linux-snps-arc, linux-hexagon, linux-openrisc, sparclinux,
linux-arch, Michal Suchánek, Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.816918647@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> Randomizing the syscall stack can only happen after state is established
> via enter_from_user_mode() or syscall_enter_from_user_mode(). The earlier
> it happens the better.
>
> Provide two new macros to consolidate that:
>
> - enter_from_user_mode_randomize_stack()
> enter_from_user_mode();
> add_random_kstack_offset_irqsoff();
>
> - syscall_enter_from_user_mode_randomize_stack()
> enter_from_user_mode_randomize_stack();
> syscall_enter_from_user_mode_work();
>
> to reduce boiler plate code.
>
> Those are macros and not inline functions as the latter would limit the
> stack randomization scope to the inline function itself.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> ---
> include/linux/entry-common.h | 56 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 56 insertions(+)
>
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -6,6 +6,7 @@
> #include <linux/irq-entry-common.h>
> #include <linux/livepatch.h>
> #include <linux/ptrace.h>
> +#include <linux/randomize_kstack.h>
> #include <linux/resume_user_mode.h>
> #include <linux/seccomp.h>
> #include <linux/sched.h>
> @@ -150,6 +151,61 @@ static __always_inline long syscall_ente
> }
>
> /**
> + * enter_from_user_mode_randomize_stack - Establish state and add stack randomization
> + * before invoking syscall_enter_from_user_mode_work()
> + * @regs: Pointer to currents pt_regs
^^^^^^^^
Nit: current
> + *
> + * Invoked from architecture specific syscall entry code with interrupts
> + * disabled. The calling code has to be non-instrumentable. When the function
> + * returns all state is correct, interrupts are still disabled and the
> + * subsequent functions can be instrumented.
> + *
> + * Implemented as a macro so that the stack randomization is effective
> + * throughout the function in which it is invoked. An inline would only make it
> + * effective in the scope of the inline function.
> + */
> +#define enter_from_user_mode_randomize_stack(regs) \
> +do { \
> + enter_from_user_mode(regs); \
> + instrumentation_begin(); \
> + add_random_kstack_offset_irqsoff(); \
> + instrumentation_end(); \
> +} while (0)
> +
> +/**
> + * syscall_enter_from_user_mode_randomize_stack - Establish state and check and handle work
> + * before invoking a syscall
> + * @regs: Pointer to currents pt_regs
^^^^^^^^
Same here.
> + * @syscall: The syscall number
> + *
> + * Invoked from architecture specific syscall entry code with interrupts
> + * disabled. The calling code has to be non-instrumentable. When the
> + * function returns all state is correct, interrupts are enabled and the
> + * subsequent functions can be instrumented.
> + *
> + * This is the combination of enter_from_user_mode_randomize_stack() and
> + * syscall_enter_from_user_mode_work() to be used when there is no
> + * architecture specific work to be done between the two.
> + *
> + * Returns: The original or a modified syscall number. See
> + * syscall_enter_from_user_mode_work() for further explanation.
> + *
> + * Implemented as a macro to make stack randomization effective in the calling
> + * scope.
> + */
> +#define syscall_enter_from_user_mode_randomize_stack(regs, syscall) \
> +({ \
> + enter_from_user_mode_randomize_stack(regs); \
> + \
> + instrumentation_begin(); \
> + local_irq_enable(); \
> + long _ret = syscall_enter_from_user_mode_work(regs, syscall); \
> + instrumentation_end(); \
> + \
> + _ret; \
> +})
> +
> +/**
> * syscall_enter_from_user_mode - Establish state and check and handle work
> * before invoking a syscall
> * @regs: Pointer to currents pt_regs
With the above nits,
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
* Re: [patch 02/18] randomize_kstack: Provide add_random_kstack_offset_irqsoff()
From: Radu Rendec @ 2026-07-08 17:24 UTC (permalink / raw)
To: Thomas Gleixner, LKML
Cc: Peter Zijlstra, Kees Cook, Michael Ellerman, Shrikanth Hegde,
linuxppc-dev, Huacai Chen, loongarch, Paul Walmsley,
Palmer Dabbelt, linux-riscv, Sven Schnelle, linux-s390, x86,
Mark Rutland, Jinjie Ruan, Andy Lutomirski, Oleg Nesterov,
Richard Henderson, Russell King, Catalin Marinas, Guo Ren,
Geert Uytterhoeven, Thomas Bogendoerfer, Helge Deller,
Yoshinori Sato, Richard Weinberger, Chris Zankel,
linux-arm-kernel, linux-alpha, linux-csky, linux-m68k, linux-mips,
linux-parisc, linux-sh, linux-um, Arnd Bergmann, Vineet Gupta,
Will Deacon, Brian Cain, Michal Simek, Dinh Nguyen,
David S. Miller, Andreas Larsson, linux-snps-arc, linux-hexagon,
linux-openrisc, sparclinux, linux-arch, Michal Suchánek,
Jonathan Corbet, linux-doc
In-Reply-To: <20260707190253.768842729@kernel.org>
On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> add_random_kstack_offset() uses get/put_cpu_var() which is pointless
> overhead when it is invoked from low level entry code with interrupts
> disabled.
>
> Provide a irqsoff() variant, which avoids that.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>
> Cc: Kees Cook <kees@kernel.org>
> ---
> include/linux/randomize_kstack.h | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> --- a/include/linux/randomize_kstack.h
> +++ b/include/linux/randomize_kstack.h
> @@ -77,8 +77,27 @@ static __always_inline u32 get_kstack_of
> } \
> } while (0)
>
> +/**
> + * add_random_kstack_offset_irqsoff - Increase stack utilization by a random offset.
> + *
> + * This should be used in the syscall entry path after user registers have been
> + * stored to the stack. Interrupts must be still disabled.
> + */
> +#define add_random_kstack_offset_irqsoff() \
> +do { \
> + lockdep_assert_irqs_disabled(); \
> + if (static_branch_maybe(CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT, \
> + &randomize_kstack_offset)) { \
> + u32 offset = prandom_u32_state(raw_cpu_ptr(&kstack_rnd_state)); \
> + u8 *ptr = __kstack_alloca(KSTACK_OFFSET_MAX(offset)); \
> + /* Keep allocation even after "ptr" loses scope. */ \
> + asm volatile("" :: "r"(ptr) : "memory"); \
> + } \
> +} while (0)
> +
> #else /* CONFIG_RANDOMIZE_KSTACK_OFFSET */
> #define add_random_kstack_offset() do { } while (0)
> +#define add_random_kstack_offset_irqsoff() do { } while (0)
> #endif /* CONFIG_RANDOMIZE_KSTACK_OFFSET */
>
> #endif
Reviewed-by: Radu Rendec <radu@rendec.net>
^ permalink raw reply
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