| Message ID | 20190319232753.26521-1-julien.grall@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | [Xen-devel] xen/arm64: head: Combine lsl and str instructions in a single one | expand |
On Tue, 19 Mar 2019, Julien Grall wrote: > From: Julien Grall <julien.grall@linaro.org> > > We can optimize a bit the assembly code by combining the 2 instructions > in a single one. This likely not going to make the code faster, but > likely make easier to read the assembly. > > Signed-off-by: Julien Grall <julien.grall@linaro.org> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> > --- > xen/arch/arm/arm64/head.S | 12 ++++-------- > 1 file changed, 4 insertions(+), 8 deletions(-) > > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S > index 0b7f6e7f92..4589a37874 100644 > --- a/xen/arch/arm/arm64/head.S > +++ b/xen/arch/arm/arm64/head.S > @@ -418,8 +418,7 @@ skip_bss: > > mov x3, #PT_PT /* x2 := table map of boot_first_id */ > orr x2, x2, x3 /* + rights for linear PT */ > - lsl x1, x1, #3 /* x1 := Slot offset */ > - str x2, [x4, x1] > + str x2, [x4, x1, lsl #3] > > load_paddr x4, boot_first_id > > @@ -428,8 +427,7 @@ skip_bss: > mov x3, #PT_MEM /* x2 := Section map */ > orr x2, x2, x3 > and x1, x1, #LPAE_ENTRY_MASK /* x1 := Slot offset */ > - lsl x1, x1, #3 > - str x2, [x4, x1] /* Mapping of paddr(start) */ > + str x2, [x4, x1, lsl #3] /* Mapping of paddr(start) */ > mov x25, #1 /* x25 := identity map now in place */ > > 1: /* Setup boot_first: */ > @@ -450,8 +448,7 @@ skip_bss: > lsl x2, x2, #FIRST_SHIFT /* Base address for 1GB mapping */ > mov x3, #PT_MEM /* x2 := Section map */ > orr x2, x2, x3 > - lsl x1, x1, #3 /* x1 := Slot offset */ > - str x2, [x4, x1] /* Create mapping of paddr(start)*/ > + str x2, [x4, x1, lsl #3] /* Create mapping of paddr(start)*/ > mov x25, #1 /* x25 := identity map now in place */ > > 1: /* Setup boot_second: */ > @@ -473,8 +470,7 @@ skip_bss: > lsl x2, x2, #SECOND_SHIFT /* Base address for 2MB mapping */ > mov x3, #PT_MEM /* x2 := Section map */ > orr x2, x2, x3 > - lsl x1, x1, #3 /* x1 := Slot offset */ > - str x2, [x4, x1] /* Create mapping of paddr(start)*/ > + str x2, [x4, x1, lsl #3] /* Create mapping of paddr(start)*/ > mov x25, #1 /* x25 := identity map now in place */ > > 1: /* Setup boot_third: */ > -- > 2.11.0 >
Hi, On 16/04/2019 22:07, Stefano Stabellini wrote: > On Tue, 19 Mar 2019, Julien Grall wrote: >> From: Julien Grall <julien.grall@linaro.org> >> >> We can optimize a bit the assembly code by combining the 2 instructions >> in a single one. This likely not going to make the code faster, but >> likely make easier to read the assembly. >> >> Signed-off-by: Julien Grall <julien.grall@linaro.org> > > Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Thank you! I have pushed to my branch next-4.13 for now. It will be merged once the commit moratorium is lifted. Cheers,
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index 0b7f6e7f92..4589a37874 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -418,8 +418,7 @@ skip_bss: mov x3, #PT_PT /* x2 := table map of boot_first_id */ orr x2, x2, x3 /* + rights for linear PT */ - lsl x1, x1, #3 /* x1 := Slot offset */ - str x2, [x4, x1] + str x2, [x4, x1, lsl #3] load_paddr x4, boot_first_id @@ -428,8 +427,7 @@ skip_bss: mov x3, #PT_MEM /* x2 := Section map */ orr x2, x2, x3 and x1, x1, #LPAE_ENTRY_MASK /* x1 := Slot offset */ - lsl x1, x1, #3 - str x2, [x4, x1] /* Mapping of paddr(start) */ + str x2, [x4, x1, lsl #3] /* Mapping of paddr(start) */ mov x25, #1 /* x25 := identity map now in place */ 1: /* Setup boot_first: */ @@ -450,8 +448,7 @@ skip_bss: lsl x2, x2, #FIRST_SHIFT /* Base address for 1GB mapping */ mov x3, #PT_MEM /* x2 := Section map */ orr x2, x2, x3 - lsl x1, x1, #3 /* x1 := Slot offset */ - str x2, [x4, x1] /* Create mapping of paddr(start)*/ + str x2, [x4, x1, lsl #3] /* Create mapping of paddr(start)*/ mov x25, #1 /* x25 := identity map now in place */ 1: /* Setup boot_second: */ @@ -473,8 +470,7 @@ skip_bss: lsl x2, x2, #SECOND_SHIFT /* Base address for 2MB mapping */ mov x3, #PT_MEM /* x2 := Section map */ orr x2, x2, x3 - lsl x1, x1, #3 /* x1 := Slot offset */ - str x2, [x4, x1] /* Create mapping of paddr(start)*/ + str x2, [x4, x1, lsl #3] /* Create mapping of paddr(start)*/ mov x25, #1 /* x25 := identity map now in place */ 1: /* Setup boot_third: */