From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Wei Liu" <wl@xen.org>, "Jan Beulich" <JBeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH 3/7] x86/ucode/intel: Remove gratuitous memory allocations from cpu_request_microcode()
Date: Mon, 23 Mar 2020 10:17:20 +0000 [thread overview]
Message-ID: <20200323101724.15655-4-andrew.cooper3@citrix.com> (raw)
In-Reply-To: <20200323101724.15655-1-andrew.cooper3@citrix.com>
cpu_request_microcode() needs to scan its container and duplicate one blob,
but the get_next_ucode_from_buffer() helper duplicates every blob in turn.
Furthermore, the length checking is only safe from overflow in 64bit builds.
Delete get_next_ucode_from_buffer() and alter the purpose of the saved
variable to simply point somewhere in buf until we're ready to return.
This is only a modest reduction in absolute code size (-144), but avoids
making memory allocations for every blob in the container.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wl@xen.org>
CC: Roger Pau Monné <roger.pau@citrix.com>
---
xen/arch/x86/cpu/microcode/intel.c | 69 ++++++++++++++------------------------
1 file changed, 26 insertions(+), 43 deletions(-)
diff --git a/xen/arch/x86/cpu/microcode/intel.c b/xen/arch/x86/cpu/microcode/intel.c
index f0beefe1bb..0cceac6255 100644
--- a/xen/arch/x86/cpu/microcode/intel.c
+++ b/xen/arch/x86/cpu/microcode/intel.c
@@ -321,75 +321,58 @@ static int apply_microcode(const struct microcode_patch *patch)
return 0;
}
-static long get_next_ucode_from_buffer(struct microcode_intel **mc,
- const uint8_t *buf, unsigned long size,
- unsigned long offset)
-{
- struct microcode_header_intel *mc_header;
- unsigned long total_size;
-
- /* No more data */
- if ( offset >= size )
- return 0;
- mc_header = (struct microcode_header_intel *)(buf + offset);
- total_size = get_totalsize(mc_header);
-
- if ( (offset + total_size) > size )
- {
- printk(KERN_ERR "microcode: error! Bad data in microcode data file\n");
- return -EINVAL;
- }
-
- *mc = xmemdup_bytes(mc_header, total_size);
- if ( *mc == NULL )
- return -ENOMEM;
-
- return offset + total_size;
-}
-
static struct microcode_patch *cpu_request_microcode(const void *buf,
size_t size)
{
- long offset = 0;
int error = 0;
- struct microcode_intel *mc, *saved = NULL;
+ const struct microcode_intel *saved = NULL;
struct microcode_patch *patch = NULL;
- while ( (offset = get_next_ucode_from_buffer(&mc, buf, size, offset)) > 0 )
+ while ( size )
{
- error = microcode_sanity_check(mc);
- if ( error )
+ const struct microcode_intel *mc;
+ unsigned int blob_size;
+
+ if ( size < MC_HEADER_SIZE || /* Insufficient space for header? */
+ (mc = buf)->hdr.hdrver != 1 || /* Unrecognised header version? */
+ mc->hdr.ldrver != 1 || /* Unrecognised loader version? */
+ size < (blob_size = /* Insufficient space for patch? */
+ get_totalsize(&mc->hdr)) )
{
- xfree(mc);
+ error = -EINVAL;
break;
}
+ error = microcode_sanity_check(mc);
+ if ( error )
+ break;
+
/*
* If the new update covers current CPU, compare updates and store the
* one with higher revision.
*/
if ( (microcode_update_match(mc) != MIS_UCODE) &&
(!saved || (mc->hdr.rev > saved->hdr.rev)) )
- {
- xfree(saved);
saved = mc;
- }
- else
- xfree(mc);
+
+ buf += blob_size;
+ size -= blob_size;
}
- if ( offset < 0 )
- error = offset;
if ( saved )
{
patch = xmalloc(struct microcode_patch);
if ( patch )
- patch->mc_intel = saved;
- else
{
- xfree(saved);
- error = -ENOMEM;
+ patch->mc_intel = xmemdup_bytes(saved, get_totalsize(&saved->hdr));
+ if ( !patch->mc_intel )
+ {
+ XFREE(patch);
+ error = -ENOMEM;
+ }
}
+ else
+ error = -ENOMEM;
}
if ( error && !patch )
--
2.11.0
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next prev parent reply other threads:[~2020-03-23 10:18 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 10:17 [Xen-devel] [PATCH 0/7] x86/ucode: Cleanup and fixes - Part 3/n (Intel) Andrew Cooper
2020-03-23 10:17 ` [Xen-devel] [PATCH 1/7] x86/ucode: Document the behaviour of the microcode_ops hooks Andrew Cooper
2020-03-23 12:33 ` Jan Beulich
2020-03-23 13:26 ` Andrew Cooper
2020-03-23 14:24 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 2/7] x86/ucode/intel: Adjust microcode_sanity_check() to not take void * Andrew Cooper
2020-03-25 13:23 ` Jan Beulich
2020-03-23 10:17 ` Andrew Cooper [this message]
2020-03-25 13:34 ` [Xen-devel] [PATCH 3/7] x86/ucode/intel: Remove gratuitous memory allocations from cpu_request_microcode() Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 4/7] x86/ucode/intel: Reimplement get_{data, total}size() helpers Andrew Cooper
2020-03-25 13:41 ` Jan Beulich
2020-03-26 14:35 ` Andrew Cooper
2020-03-26 14:56 ` Jan Beulich
2020-03-26 15:09 ` Andrew Cooper
2020-03-26 15:19 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 5/7] x86/ucode/intel: Clean up microcode_update_match() Andrew Cooper
2020-03-25 13:51 ` Jan Beulich
2020-03-26 14:36 ` Andrew Cooper
2020-03-23 10:17 ` [Xen-devel] [PATCH 6/7] x86/ucode/intel: Clean up microcode_sanity_check() Andrew Cooper
2020-03-25 14:07 ` Jan Beulich
2020-03-26 14:41 ` Andrew Cooper
2020-03-26 15:02 ` Jan Beulich
2020-03-23 10:17 ` [Xen-devel] [PATCH 7/7] x86/ucode/intel: Fold structures together Andrew Cooper
2020-03-25 14:16 ` Jan Beulich
2020-03-25 14:32 ` Andrew Cooper
2020-03-26 12:24 ` Jan Beulich
2020-03-26 14:50 ` Andrew Cooper
2020-03-26 15:05 ` Jan Beulich
2020-03-27 12:40 ` Andrew Cooper
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