From 7b6e7d009872af68319e9a91725911829cc59fb7 Mon Sep 17 00:00:00 2001 From: Dun Tan Date: Thu, 20 Apr 2023 16:06:52 +0800 Subject: UefiCpuPkg/PiSmmCpuDxeSmm: Add 2 function to disable/enable CR0.WP Add two functions to disable/enable CR0.WP. These two unctions will also be used in later commits. This commit doesn't change any functionality. Signed-off-by: Dun Tan Cc: Eric Dong Reviewed-by: Ray Ni Cc: Rahul Kumar Cc: Gerd Hoffmann --- UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 24 +++++ UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 115 ++++++++++++--------- 2 files changed, 90 insertions(+), 49 deletions(-) (limited to 'UefiCpuPkg/PiSmmCpuDxeSmm') diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h index 4f1b42d932..c912e9f0e3 100644 --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h @@ -1567,4 +1567,28 @@ SmmWaitForApArrival ( VOID ); +/** + Disable Write Protect on pages marked as read-only if Cr0.Bits.WP is 1. + + @param[out] WpEnabled If Cr0.WP is enabled. + @param[out] CetEnabled If CET is enabled. +**/ +VOID +DisableReadOnlyPageWriteProtect ( + OUT BOOLEAN *WpEnabled, + OUT BOOLEAN *CetEnabled + ); + +/** + Enable Write Protect on pages marked as read-only. + + @param[out] WpEnabled If Cr0.WP should be enabled. + @param[out] CetEnabled If CET should be enabled. +**/ +VOID +EnableReadOnlyPageWriteProtect ( + BOOLEAN WpEnabled, + BOOLEAN CetEnabled + ); + #endif diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c index 1aba7a9d76..8888c26ffd 100644 --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c @@ -40,6 +40,64 @@ PAGE_TABLE_POOL *mPageTablePool = NULL; // BOOLEAN mIsReadOnlyPageTable = FALSE; +/** + Disable Write Protect on pages marked as read-only if Cr0.Bits.WP is 1. + + @param[out] WpEnabled If Cr0.WP is enabled. + @param[out] CetEnabled If CET is enabled. +**/ +VOID +DisableReadOnlyPageWriteProtect ( + OUT BOOLEAN *WpEnabled, + OUT BOOLEAN *CetEnabled + ) +{ + IA32_CR0 Cr0; + + *CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE; + Cr0.UintN = AsmReadCr0 (); + *WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE; + if (*WpEnabled) { + if (*CetEnabled) { + // + // CET must be disabled if WP is disabled. Disable CET before clearing CR0.WP. + // + DisableCet (); + } + + Cr0.Bits.WP = 0; + AsmWriteCr0 (Cr0.UintN); + } +} + +/** + Enable Write Protect on pages marked as read-only. + + @param[out] WpEnabled If Cr0.WP should be enabled. + @param[out] CetEnabled If CET should be enabled. +**/ +VOID +EnableReadOnlyPageWriteProtect ( + BOOLEAN WpEnabled, + BOOLEAN CetEnabled + ) +{ + IA32_CR0 Cr0; + + if (WpEnabled) { + Cr0.UintN = AsmReadCr0 (); + Cr0.Bits.WP = 1; + AsmWriteCr0 (Cr0.UintN); + + if (CetEnabled) { + // + // re-enable CET. + // + EnableCet (); + } + } +} + /** Initialize a buffer pool for page table use only. @@ -62,10 +120,9 @@ InitializePageTablePool ( IN UINTN PoolPages ) { - VOID *Buffer; - BOOLEAN CetEnabled; - BOOLEAN WpEnabled; - IA32_CR0 Cr0; + VOID *Buffer; + BOOLEAN WpEnabled; + BOOLEAN CetEnabled; // // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for @@ -102,34 +159,9 @@ InitializePageTablePool ( // If page table memory has been marked as RO, mark the new pool pages as read-only. // if (mIsReadOnlyPageTable) { - CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE; - Cr0.UintN = AsmReadCr0 (); - WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE; - if (WpEnabled) { - if (CetEnabled) { - // - // CET must be disabled if WP is disabled. Disable CET before clearing CR0.WP. - // - DisableCet (); - } - - Cr0.Bits.WP = 0; - AsmWriteCr0 (Cr0.UintN); - } - + DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO); - if (WpEnabled) { - Cr0.UintN = AsmReadCr0 (); - Cr0.Bits.WP = 1; - AsmWriteCr0 (Cr0.UintN); - - if (CetEnabled) { - // - // re-enable CET. - // - EnableCet (); - } - } + EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); } return TRUE; @@ -1786,6 +1818,7 @@ SetPageTableAttributes ( VOID ) { + BOOLEAN WpEnabled; BOOLEAN CetEnabled; if (!IfReadOnlyPageTableNeeded ()) { @@ -1799,15 +1832,7 @@ SetPageTableAttributes ( // Disable write protection, because we need mark page table to be write protected. // We need *write* page table memory, to mark itself to be *read only*. // - CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE; - if (CetEnabled) { - // - // CET must be disabled if WP is disabled. - // - DisableCet (); - } - - AsmWriteCr0 (AsmReadCr0 () & ~CR0_WP); + DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); // Set memory used by page table as Read Only. DEBUG ((DEBUG_INFO, "Start...\n")); @@ -1816,20 +1841,12 @@ SetPageTableAttributes ( // // Enable write protection, after page table attribute updated. // - AsmWriteCr0 (AsmReadCr0 () | CR0_WP); + EnableReadOnlyPageWriteProtect (TRUE, CetEnabled); mIsReadOnlyPageTable = TRUE; // // Flush TLB after mark all page table pool as read only. // FlushTlbForAll (); - - if (CetEnabled) { - // - // re-enable CET. - // - EnableCet (); - } - PERF_FUNCTION_END (); } -- cgit v1.2.3