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powerpc: Introduce syscall exit arch functions

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Add PowerPC-specific implementations of the generic syscall exit hooks
used by the generic entry/exit framework:

 - arch_exit_to_user_mode_work_prepare()
 - arch_exit_to_user_mode_work()

These helpers handle user state restoration when returning from the
kernel to userspace, including FPU/VMX/VSX state, transactional memory,
KUAP restore, and per-CPU accounting.

Additionally, move check_return_regs_valid() from interrupt.c to
interrupt.h so it can be shared by the new entry/exit logic.

No functional change is intended with this patch.

Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
Tested-by: Samir M <samir@linux.ibm.com>
Tested-by: David Gow <davidgow@google.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260427122742.210074-5-mkchauras@gmail.com
This commit is contained in:
Mukesh Kumar Chaurasiya 2026-04-27 17:57:38 +05:30 committed by Madhavan Srinivasan
parent 09a9d3a849
commit 02565a782c
1 changed files with 49 additions and 0 deletions
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49
arch/powerpc/include/asm/entry-common.h
View File

@ -6,6 +6,7 @@
#include <asm/cputime.h>
#include <asm/interrupt.h>
#include <asm/stacktrace.h>
#include <asm/switch_to.h>
#include <asm/tm.h>
static __always_inline void booke_load_dbcr0(void)
@ -123,4 +124,52 @@ static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs)
#define arch_enter_from_user_mode arch_enter_from_user_mode
static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
unsigned long ti_work)
{
unsigned long mathflags;
if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && IS_ENABLED(CONFIG_PPC_FPU)) {
if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
unlikely((ti_work & _TIF_RESTORE_TM))) {
restore_tm_state(regs);
} else {
mathflags = MSR_FP;
if (cpu_has_feature(CPU_FTR_VSX))
mathflags |= MSR_VEC | MSR_VSX;
else if (cpu_has_feature(CPU_FTR_ALTIVEC))
mathflags |= MSR_VEC;
/*
* If userspace MSR has all available FP bits set,
* then they are live and no need to restore. If not,
* it means the regs were given up and restore_math
* may decide to restore them (to avoid taking an FP
* fault).
*/
if ((regs->msr & mathflags) != mathflags)
restore_math(regs);
}
}
check_return_regs_valid(regs);
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
local_paca->tm_scratch = regs->msr;
#endif
/* Restore user access locks last */
kuap_user_restore(regs);
}
#define arch_exit_to_user_mode_prepare arch_exit_to_user_mode_prepare
static __always_inline void arch_exit_to_user_mode(void)
{
booke_load_dbcr0();
account_cpu_user_exit();
}
#define arch_exit_to_user_mode arch_exit_to_user_mode
#endif /* _ASM_PPC_ENTRY_COMMON_H */