112 lines
4.9 KiB
Diff
112 lines
4.9 KiB
Diff
From ef99dec08d51bad7be0f84942443a8a0e1412c87 Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Tue, 16 Jan 2024 18:11:01 +0100
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Subject: [PATCH 2/6] OvmfPkg/VirtNorFlashDxe: clarify block write logic & fix
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shadowbuffer reads
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RH-Author: Gerd Hoffmann <None>
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RH-MergeRequest: 52: OvmfPkg/VirtNorFlashDxe: backport more fixes.
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RH-Jira: RHEL-20963
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [2/6] e2f2231fd1b7b702aa5372e790c1d2c06ca79f74 (kraxel.rh/centos-src-edk2)
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Introduce 'Start' and 'End' variables to make it easier to follow the
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logic and code flow. Also add a ascii art diagram (based on a
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suggestion by Laszlo).
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This also fixes the 'Size' calculation for the NorFlashRead() call.
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Without this patch the code will read only one instead of two
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P30_MAX_BUFFER_SIZE_IN_BYTES blocks in case '*NumBytes' is smaller than
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P30_MAX_BUFFER_SIZE_IN_BYTES but 'Offset + *NumBytes' is not, i.e. the
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update range crosses a P30_MAX_BUFFER_SIZE_IN_BYTES boundary.
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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Reviewed-by: Laszlo Ersek <lersek@redhat.com>
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Message-Id: <20240116171105.37831-3-kraxel@redhat.com>
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(cherry picked from commit 35d8ea8097794b522149688b5cfaf8364bc44d54)
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---
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OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c | 36 ++++++++++++++++++++------
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1 file changed, 28 insertions(+), 8 deletions(-)
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diff --git a/OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c b/OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c
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index 7f4743b003..88a4d2c23f 100644
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--- a/OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c
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+++ b/OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c
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@@ -520,6 +520,7 @@ NorFlashWriteSingleBlock (
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UINTN BlockSize;
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UINTN BlockAddress;
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UINT8 *OrigData;
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+ UINTN Start, End;
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DEBUG ((DEBUG_BLKIO, "NorFlashWriteSingleBlock(Parameters: Lba=%ld, Offset=0x%x, *NumBytes=0x%x, Buffer @ 0x%08x)\n", Lba, Offset, *NumBytes, Buffer));
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@@ -555,7 +556,28 @@ NorFlashWriteSingleBlock (
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// To avoid pathological cases were a 2 byte write is disregarded because it
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// occurs right at a 128 byte buffered write alignment boundary, permit up to
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// twice the max buffer size, and perform two writes if needed.
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- if ((*NumBytes + (Offset & BOUNDARY_OF_32_WORDS)) <= (2 * P30_MAX_BUFFER_SIZE_IN_BYTES)) {
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+ //
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+ // 0 128 256
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+ // [----------------|----------------]
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+ // ^ ^ ^ ^
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+ // | | | |
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+ // | | | End, the next "word" boundary beyond
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+ // | | | the (logical) update
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+ // | | |
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+ // | | (Offset & BOUNDARY_OF_32_WORDS) + NumBytes;
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+ // | | i.e., the relative offset inside (or just past)
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+ // | | the *double-word* such that it is the
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+ // | | *exclusive* end of the (logical) update.
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+ // | |
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+ // | Offset & BOUNDARY_OF_32_WORDS; i.e., Offset within the "word";
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+ // | this is where the (logical) update is supposed to start
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+ // |
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+ // Start = Offset & ~BOUNDARY_OF_32_WORDS; i.e., Offset truncated to "word" boundary
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+
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+ Start = Offset & ~BOUNDARY_OF_32_WORDS;
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+ End = ALIGN_VALUE (Offset + *NumBytes, P30_MAX_BUFFER_SIZE_IN_BYTES);
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+
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+ if ((End - Start) <= (2 * P30_MAX_BUFFER_SIZE_IN_BYTES)) {
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// Check to see if we need to erase before programming the data into NOR.
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// If the destination bits are only changing from 1s to 0s we can just write.
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// After a block is erased all bits in the block is set to 1.
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@@ -565,8 +587,8 @@ NorFlashWriteSingleBlock (
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Status = NorFlashRead (
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Instance,
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Lba,
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- Offset & ~BOUNDARY_OF_32_WORDS,
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- (*NumBytes | BOUNDARY_OF_32_WORDS) + 1,
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+ Start,
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+ End - Start,
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Instance->ShadowBuffer
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);
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if (EFI_ERROR (Status)) {
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@@ -601,7 +623,7 @@ NorFlashWriteSingleBlock (
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Status = NorFlashWriteBuffer (
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Instance,
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- BlockAddress + (Offset & ~BOUNDARY_OF_32_WORDS),
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+ BlockAddress + Start,
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P30_MAX_BUFFER_SIZE_IN_BYTES,
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Instance->ShadowBuffer
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);
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@@ -609,12 +631,10 @@ NorFlashWriteSingleBlock (
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goto Exit;
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}
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- if ((*NumBytes + (Offset & BOUNDARY_OF_32_WORDS)) > P30_MAX_BUFFER_SIZE_IN_BYTES) {
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- BlockAddress += P30_MAX_BUFFER_SIZE_IN_BYTES;
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-
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+ if ((End - Start) > P30_MAX_BUFFER_SIZE_IN_BYTES) {
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Status = NorFlashWriteBuffer (
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Instance,
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- BlockAddress + (Offset & ~BOUNDARY_OF_32_WORDS),
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+ BlockAddress + Start + P30_MAX_BUFFER_SIZE_IN_BYTES,
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P30_MAX_BUFFER_SIZE_IN_BYTES,
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Instance->ShadowBuffer + P30_MAX_BUFFER_SIZE_IN_BYTES
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);
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--
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2.39.3
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