[glibc] <sys/platform/x86.h>: Add Intel LAM support

[glibc] <sys/platform/x86.h>: Add Intel LAM support

[H.J. Lu]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a2e5da2cf471b5ac849bcd7d9960466b9cd28a35

commit a2e5da2cf471b5ac849bcd7d9960466b9cd28a35
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Mon Dec 21 19:56:10 2020 -0800

    <sys/platform/x86.h>: Add Intel LAM support
    
    Add Intel Linear Address Masking (LAM) support to <sys/platform/x86.h>.
    HAS_CPU_FEATURE (LAM) can be used to detect if LAM is enabled in CPU.
    
    LAM modifies the checking that is applied to 64-bit linear addresses,
    allowing software to use of the untranslated address bits for metadata.

Diff:
---
 manual/platform.texi               | 3 +++
 sysdeps/x86/sys/platform/x86.h     | 3 +++
 sysdeps/x86/tst-get-cpu-features.c | 1 +
 3 files changed, 7 insertions(+)

diff --git a/manual/platform.texi b/manual/platform.texi
index 8fec2933d6..b67683aeb3 100644
--- a/manual/platform.texi
+++ b/manual/platform.texi
@@ -377,6 +377,9 @@ the indirect branch predictor barrier (IBPB).
 @item
 @code{KL} -- AES Key Locker instructions.
 
+@item
+@code{LAM} -- Linear Address Masking.
+
 @item
 @code{L1D_FLUSH} -- IA32_FLUSH_CMD MSR.
 
diff --git a/sysdeps/x86/sys/platform/x86.h b/sysdeps/x86/sys/platform/x86.h
index 3ef92b04e8..99d8c9b0ab 100644
--- a/sysdeps/x86/sys/platform/x86.h
+++ b/sysdeps/x86/sys/platform/x86.h
@@ -317,6 +317,7 @@ extern const struct cpu_features *__x86_get_cpu_features (unsigned int)
 #define bit_cpu_FSRS		(1u << 11)
 #define bit_cpu_FSRCS		(1u << 12)
 #define bit_cpu_HRESET		(1u << 22)
+#define bit_cpu_LAM		(1u << 26)
 
 /* COMMON_CPUID_INDEX_19.  */
 
@@ -541,6 +542,7 @@ extern const struct cpu_features *__x86_get_cpu_features (unsigned int)
 #define index_cpu_FSRS		COMMON_CPUID_INDEX_7_ECX_1
 #define index_cpu_FSRCS		COMMON_CPUID_INDEX_7_ECX_1
 #define index_cpu_HRESET	COMMON_CPUID_INDEX_7_ECX_1
+#define index_cpu_LAM		COMMON_CPUID_INDEX_7_ECX_1
 
 /* COMMON_CPUID_INDEX_19.  */
 
@@ -765,6 +767,7 @@ extern const struct cpu_features *__x86_get_cpu_features (unsigned int)
 #define reg_FSRS		eax
 #define reg_FSRCS		eax
 #define reg_HRESET		eax
+#define reg_LAM			eax
 
 /* COMMON_CPUID_INDEX_19.  */
 
diff --git a/sysdeps/x86/tst-get-cpu-features.c b/sysdeps/x86/tst-get-cpu-features.c
index 667aa27117..6f1e925a6a 100644
--- a/sysdeps/x86/tst-get-cpu-features.c
+++ b/sysdeps/x86/tst-get-cpu-features.c
@@ -227,6 +227,7 @@ do_test (void)
   CHECK_CPU_FEATURE (FSRS);
   CHECK_CPU_FEATURE (FSRCS);
   CHECK_CPU_FEATURE (HRESET);
+  CHECK_CPU_FEATURE (LAM);
   CHECK_CPU_FEATURE (AESKLE);
   CHECK_CPU_FEATURE (WIDE_KL);