diff options
| author |   Christophe Leroy <christophe.leroy@csgroup.eu> | 2020-08-18 17:19:17 +0000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2020-12-04 01:01:11 +1100 |
| commit | b6254ced4da6cf28d49fbffe24ee4b3286dcb3f4 (patch) | |
| tree | b540b61c16700a38016b462239cef5ff6319de9a /arch/powerpc/kernel/process.c | |
| parent | powerpc/ptrace: Create ptrace_get_fpr() and ptrace_put_fpr() (diff) | |
| download | linux-dev-b6254ced4da6cf28d49fbffe24ee4b3286dcb3f4.tar.xz linux-dev-b6254ced4da6cf28d49fbffe24ee4b3286dcb3f4.zip | |
powerpc/signal: Don't manage floating point regs when no FPU
There is no point in copying floating point regs when there
is no FPU and MATH_EMULATION is not selected.
Create a new CONFIG_PPC_FPU_REGS bool that is selected by
CONFIG_MATH_EMULATION and CONFIG_PPC_FPU, and use it to
opt out everything related to fp_state in thread_struct.
The asm const used only by fpu.S are opted out with CONFIG_PPC_FPU
as fpu.S build is conditionnal to CONFIG_PPC_FPU.
The following app spends approx 8.1 seconds system time on an 8xx
without the patch, and 7.0 seconds with the patch (13.5% reduction).
On an 832x, it spends approx 2.6 seconds system time without
the patch and 2.1 seconds with the patch (19% reduction).
void sigusr1(int sig) { }
int main(int argc, char **argv)
{
int i = 100000;
signal(SIGUSR1, sigusr1);
for (;i--;)
raise(SIGUSR1);
exit(0);
}
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7569070083e6cd5b279bb5023da601aba3c06f3c.1597770847.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/kernel/process.c')
| -rw-r--r-- | arch/powerpc/kernel/process.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index d421a2c7f822..ba2c987b8403 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1730,7 +1730,9 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, p->thread.ptrace_bps[i] = NULL; #endif +#ifdef CONFIG_PPC_FPU_REGS p->thread.fp_save_area = NULL; +#endif #ifdef CONFIG_ALTIVEC p->thread.vr_save_area = NULL; #endif @@ -1855,8 +1857,10 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp) #endif current->thread.load_slb = 0; current->thread.load_fp = 0; +#ifdef CONFIG_PPC_FPU_REGS memset(¤t->thread.fp_state, 0, sizeof(current->thread.fp_state)); current->thread.fp_save_area = NULL; +#endif #ifdef CONFIG_ALTIVEC memset(¤t->thread.vr_state, 0, sizeof(current->thread.vr_state)); current->thread.vr_state.vscr.u[3] = 0x00010000; /* Java mode disabled */ |