From: Benjamin Gray <bgray@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Benjamin Gray <bgray@linux.ibm.com>
Subject: [PATCH v2 3/3] powerpc/code-patching: Restore 32-bit patching performance
Date: Tue, 26 Mar 2024 09:48:48 +1100 [thread overview]
Message-ID: <20240325224848.20987-3-bgray@linux.ibm.com> (raw)
In-Reply-To: <20240325224848.20987-1-bgray@linux.ibm.com>
The new open/close abstraction makes it more difficult for a
compiler to optimise. This causes 10% worse performance on
ppc32 as in [1]. Restoring the page alignment mask and inlining
the helpers allows the compiler to better reason about the address
alignment, allowing more optimised cache flushing selection.
[1]: https://lore.kernel.org/all/77fdcdeb-4af5-4ad0-a4c6-57bf0762dc65@csgroup.eu/
Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
---
v2: * New in v2
I think Suggested-by is an appropriate tag. The patch is Christophe's
from the link, I just added the commit description, so it could well
be better to change the author to Christophe completely.
---
arch/powerpc/lib/code-patching.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index b3a644290369..d089da115987 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -282,13 +282,13 @@ struct patch_window {
* Interrupts must be disabled for the entire duration of the patching. The PIDR
* is potentially changed during this time.
*/
-static int open_patch_window(void *addr, struct patch_window *ctx)
+static __always_inline int open_patch_window(void *addr, struct patch_window *ctx)
{
unsigned long pfn = get_patch_pfn(addr);
lockdep_assert_irqs_disabled();
- ctx->text_poke_addr = (unsigned long)__this_cpu_read(cpu_patching_context.addr);
+ ctx->text_poke_addr = (unsigned long)__this_cpu_read(cpu_patching_context.addr) & PAGE_MASK;
if (!mm_patch_enabled()) {
ctx->ptep = __this_cpu_read(cpu_patching_context.pte);
@@ -331,7 +331,7 @@ static int open_patch_window(void *addr, struct patch_window *ctx)
return 0;
}
-static void close_patch_window(struct patch_window *ctx)
+static __always_inline void close_patch_window(struct patch_window *ctx)
{
lockdep_assert_irqs_disabled();
--
2.44.0
next prev parent reply other threads:[~2024-03-25 22:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-25 22:48 [PATCH v2 1/3] powerpc/code-patching: Introduce open_patch_window()/close_patch_window() Benjamin Gray
2024-03-25 22:48 ` [PATCH v2 2/3] powerpc/code-patching: Convert to open_patch_window()/close_patch_window() Benjamin Gray
2024-03-25 22:48 ` Benjamin Gray [this message]
2024-03-26 7:15 ` [PATCH v2 3/3] powerpc/code-patching: Restore 32-bit patching performance Christophe Leroy
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