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alpha: stop storing the user stack pointer in pt_regs

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Nothing reads pt_regs->usp now that user_stack_pointer() uses the PCB.
Drop the stores, which saves a PAL_rdusp call on every syscall, and
give the field back its old name.

Assisted-by: Claude:claude-opus-5-5
Reviewed-by: Magnus Lindholm <linmag7@gmail.com>
Tested-by: Magnus Lindholm <linmag7@gmail.com>
Acked-by: Ian Rogers <irogers@google.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>
Link: https://lore.kernel.org/r/20261018-alpha-perf-regs-v3-v3-2-52be85332c57@gmail.com
Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
This commit is contained in:
Matt Turner 2026-10-18 10:22:02 -04:00 committed by Magnus Lindholm
parent bceba446fa
commit 501bcb5953
4 changed files with 1 additions and 15 deletions
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2
arch/alpha/include/uapi/asm/ptrace.h
View File

@ -43,7 +43,7 @@ struct pt_regs {
unsigned long trap_a1;
unsigned long trap_a2;
/* This makes the stack 16-byte aligned as GCC expects */
unsigned long usp;
unsigned long __pad0;
/* These are saved by PAL-code: */
unsigned long ps;
unsigned long pc;

1
arch/alpha/kernel/asm-offsets.c
View File

@ -30,7 +30,6 @@ static void __used foo(void)
DEFINE(HAE_CACHE, offsetof(struct alpha_machine_vector, hae_cache));
DEFINE(HAE_REG, offsetof(struct alpha_machine_vector, hae_register));
DEFINE(PT_REGS_USP, offsetof(struct pt_regs, usp));
DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
DEFINE(TI_SYSCALL_WORK, offsetof(struct thread_info, syscall_work));

5
arch/alpha/kernel/entry.S
View File

@ -476,11 +476,6 @@ entSys:
ldq $1, 0($sp) /* syscall nr from saved r0 */
stq $1, 8($sp) /* regs->r1 = shadow syscall nr */
mov $0, $8
call_pal PAL_rdusp
stq $0, PT_REGS_USP($sp)
mov $8, $0
lda $8, 0x3fff
bic $sp, $8, $8

8
arch/alpha/kernel/traps.c
View File

@ -30,12 +30,6 @@
#include "proto.h"
static __always_inline void alpha_snapshot_usp(struct pt_regs *regs)
{
if (user_mode(regs))
regs->usp = rdusp();
}
void
dik_show_regs(struct pt_regs *regs, unsigned long *r9_15)
{
@ -186,7 +180,6 @@ do_entArith(unsigned long summary, unsigned long write_mask,
{
long si_code = FPE_FLTINV;
alpha_snapshot_usp(regs);
if (summary & 1) {
/* Software-completion summary bit is set, so try to
emulate the instruction. If the processor supports
@ -208,7 +201,6 @@ do_entIF(unsigned long type, struct pt_regs *regs)
{
int signo, code;
alpha_snapshot_usp(regs);
if (type == 3) { /* FEN fault */
/* Irritating users can call PAL_clrfen to disable the
FPU for the process. The kernel will then trap in