[v2,13/35] acpigen: Support writing a length

Message ID 20200510203409.203520-11-sjg@chromium.org
State New
Headers show
Series
  • dm: Add programmatic generation of ACPI tables (part B)
Related show

Commit Message

Simon Glass May 10, 2020, 8:33 p.m.
It is convenient to write a length value for preceding a block of data.
Of course the length is not known or is hard to calculate a priori. So add
a way to mark the start on a stack, so the length can be updated when
known.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

Changes in v2: None
Changes in v1: None

 include/acpi/acpigen.h |  3 ++
 include/dm/acpi.h      |  7 +++++
 lib/acpi/acpigen.c     | 33 ++++++++++++++++++++++
 test/dm/acpigen.c      | 64 ++++++++++++++++++++++++++++++++++++++++--
 4 files changed, 105 insertions(+), 2 deletions(-)

Comments

Wolfgang Wallner May 19, 2020, 1:14 p.m. | #1
Hi Simon,

-----"Simon Glass" <sjg at chromium.org> schrieb: -----
> Betreff: [PATCH v2 13/35] acpigen: Support writing a length
> 
> It is convenient to write a length value for preceding a block of data.
> Of course the length is not known or is hard to calculate a priori. So add
> a way to mark the start on a stack, so the length can be updated when
> known.
> 
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
> 
> Changes in v2: None
> Changes in v1: None
> 
>  include/acpi/acpigen.h |  3 ++
>  include/dm/acpi.h      |  7 +++++
>  lib/acpi/acpigen.c     | 33 ++++++++++++++++++++++
>  test/dm/acpigen.c      | 64 ++++++++++++++++++++++++++++++++++++++++--
>  4 files changed, 105 insertions(+), 2 deletions(-)
> 
> diff --git a/include/acpi/acpigen.h b/include/acpi/acpigen.h
> index 7365cce738..31366f5e34 100644
> --- a/include/acpi/acpigen.h
> +++ b/include/acpi/acpigen.h
> @@ -65,4 +65,7 @@ void acpigen_emit_stream(struct acpi_ctx *ctx, const char *data, int size);
>   */
>  void acpigen_emit_string(struct acpi_ctx *ctx, const char *str);
>  
> +void acpigen_write_len_f(struct acpi_ctx *ctx);
> +void acpigen_pop_len(struct acpi_ctx *ctx);
> +
>  #endif
> diff --git a/include/dm/acpi.h b/include/dm/acpi.h
> index 7563a4c60a..2bd03eaa0a 100644
> --- a/include/dm/acpi.h
> +++ b/include/dm/acpi.h
> @@ -22,6 +22,9 @@
>  /* Length of an ACPI name string including nul terminator */
>  #define ACPI_NAME_MAX	(ACPI_NAME_LEN + 1)
>  
> +/* Number of nested objects supported */
> +#define ACPIGEN_LENSTACK_SIZE 10
> +
>  #if !defined(__ACPI__)
>  
>  /**
> @@ -34,12 +37,16 @@
>   *	adding a new table. The RSDP holds pointers to the RSDT and XSDT.
>   * @rsdt: Pointer to the Root System Description Table
>   * @xsdt: Pointer to the Extended System Description Table
> + * @len_stack: Stack of 'length' words to fix up later
> + * @ltop: Points to current top of stack (0 = empty)
>   */
>  struct acpi_ctx {
>  	void *current;
>  	struct acpi_rsdp *rsdp;
>  	struct acpi_rsdt *rsdt;
>  	struct acpi_xsdt *xsdt;
> +	char *len_stack[ACPIGEN_LENSTACK_SIZE];
> +	int ltop;
>  };
>  
>  /**
> diff --git a/lib/acpi/acpigen.c b/lib/acpi/acpigen.c
> index 1223f0d1c4..bd1fa24fb6 100644
> --- a/lib/acpi/acpigen.c
> +++ b/lib/acpi/acpigen.c
> @@ -10,6 +10,7 @@
>  
>  #include <common.h>
>  #include <dm.h>
> +#include <log.h>
>  #include <acpi/acpigen.h>
>  #include <dm/acpi.h>
>  
> @@ -37,6 +38,38 @@ void acpigen_emit_dword(struct acpi_ctx *ctx, uint data)
>  	acpigen_emit_byte(ctx, (data >> 24) & 0xff);
>  }
>  
> +/*
> + * Maximum length for an ACPI object generated by this code,
> + *
> + * If you need to change this, change acpigen_write_len_f(ctx) and
> + * acpigen_pop_len(ctx)
> + */
> +#define ACPIGEN_MAXLEN 0xfffff
> +
> +void acpigen_write_len_f(struct acpi_ctx *ctx)
> +{
> +	assert(ctx->ltop < (ACPIGEN_LENSTACK_SIZE - 1));
> +	ctx->len_stack[ctx->ltop++] = ctx->current;
> +	acpigen_emit_byte(ctx, 0);
> +	acpigen_emit_byte(ctx, 0);
> +	acpigen_emit_byte(ctx, 0);
> +}
> +
> +void acpigen_pop_len(struct acpi_ctx *ctx)
> +{
> +	int len;
> +	char *p;
> +
> +	assert(ctx->ltop > 0);
> +	p = ctx->len_stack[--ctx->ltop];
> +	len = ctx->current - (void *)p;
> +	assert(len <= ACPIGEN_MAXLEN);
> +	/* generate store length for 0xfffff max */
> +	p[0] = (0x80 | (len & 0xf));

Nit: Without context this code is hard to understand.
I would propose adding a comment pointing to "ACPI 6.3 20.2.4 Package Length
Encoding" and using a define for 0x80 (something like ACPI_PKG_LEN_3_BYTES ...).

> +	p[1] = (len >> 4 & 0xff);
> +	p[2] = (len >> 12 & 0xff);
> +}
> +
>  void acpigen_emit_stream(struct acpi_ctx *ctx, const char *data, int size)
>  {
>  	int i;
> diff --git a/test/dm/acpigen.c b/test/dm/acpigen.c
> index 3d580a23a5..f9c15b7503 100644
> --- a/test/dm/acpigen.c
> +++ b/test/dm/acpigen.c
> @@ -22,7 +22,7 @@
>  #define TEST_STRING	"frogmore"
>  #define TEST_STREAM2	"\xfa\xde"
>  
> -static int alloc_context(struct acpi_ctx **ctxp)
> +static int alloc_context_size(struct acpi_ctx **ctxp, int size)
>  {
>  	struct acpi_ctx *ctx;
>  
> @@ -30,7 +30,8 @@ static int alloc_context(struct acpi_ctx **ctxp)
>  	ctx = malloc(sizeof(*ctx));
>  	if (!ctx)
>  		return -ENOMEM;
> -	ctx->current = malloc(150);
> +	ctx->current = malloc(size);
> +	ctx->ltop = 0;
>  	if (!ctx->current)
>  		return -ENOMEM;
>  	*ctxp = ctx;
> @@ -38,6 +39,11 @@ static int alloc_context(struct acpi_ctx **ctxp)
>  	return 0;
>  }
>  
> +static int alloc_context(struct acpi_ctx **ctxp)
> +{
> +	return alloc_context_size(ctxp, 150);
> +}
> +
>  static void free_context(struct acpi_ctx **ctxp)
>  {
>  	free(*ctxp);
> @@ -334,3 +340,57 @@ static int dm_test_acpi_spi(struct unit_test_state *uts)
>  	return 0;
>  }
>  DM_TEST(dm_test_acpi_spi, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
> +
> +/**
> + * get_length() - decode a three-byte length field
> + *
> + * @ptr: Length encoded as per ACPI
> + * @return decoded length, or -EINVAL on error
> + */
> +static int get_length(u8 *ptr)
> +{
> +	if (!(*ptr & 0x80))
> +		return -EINVAL;
> +
> +	return (*ptr & 0xf) | ptr[1] << 4 | ptr[2] << 12;
> +}
> +
> +/* Test emitting a length */
> +static int dm_test_acpi_len(struct unit_test_state *uts)
> +{
> +	const int size = 0xc0000;
> +	struct acpi_ctx *ctx;
> +	u8 *ptr;
> +	int i;
> +
> +	ut_assertok(alloc_context_size(&ctx, size));
> +
> +	ptr = acpigen_get_current(ctx);
> +
> +	/* Write a byte and a 3-byte length */
> +	acpigen_write_len_f(ctx);
> +	acpigen_emit_byte(ctx, 0x23);
> +	acpigen_pop_len(ctx);
> +	ut_asserteq(1 + 3, get_length(ptr));
> +
> +	/* Write 200 bytes so we need two length bytes */
> +	ptr = ctx->current;
> +	acpigen_write_len_f(ctx);
> +	for (i = 0; i < 200; i++)
> +		acpigen_emit_byte(ctx, 0x23);
> +	acpigen_pop_len(ctx);
> +	ut_asserteq(200 + 3, get_length(ptr));
> +
> +	/* Write 40KB so we need three length bytes */
> +	ptr = ctx->current;
> +	acpigen_write_len_f(ctx);
> +	for (i = 0; i < 40000; i++)
> +		acpigen_emit_byte(ctx, 0x23);
> +	acpigen_pop_len(ctx);
> +	ut_asserteq(40000 + 3, get_length(ptr));
> +
> +	free_context(&ctx);
> +
> +	return 0;
> +}
> +DM_TEST(dm_test_acpi_len, 0);
> -- 
> 2.26.2.645.ge9eca65c58-goog
> 

Reviewed-by: Wolfgang Wallner <wolfgang.wallner at br-automation.com>

Patch

diff --git a/include/acpi/acpigen.h b/include/acpi/acpigen.h
index 7365cce738..31366f5e34 100644
--- a/include/acpi/acpigen.h
+++ b/include/acpi/acpigen.h
@@ -65,4 +65,7 @@  void acpigen_emit_stream(struct acpi_ctx *ctx, const char *data, int size);
  */
 void acpigen_emit_string(struct acpi_ctx *ctx, const char *str);
 
+void acpigen_write_len_f(struct acpi_ctx *ctx);
+void acpigen_pop_len(struct acpi_ctx *ctx);
+
 #endif
diff --git a/include/dm/acpi.h b/include/dm/acpi.h
index 7563a4c60a..2bd03eaa0a 100644
--- a/include/dm/acpi.h
+++ b/include/dm/acpi.h
@@ -22,6 +22,9 @@ 
 /* Length of an ACPI name string including nul terminator */
 #define ACPI_NAME_MAX	(ACPI_NAME_LEN + 1)
 
+/* Number of nested objects supported */
+#define ACPIGEN_LENSTACK_SIZE 10
+
 #if !defined(__ACPI__)
 
 /**
@@ -34,12 +37,16 @@ 
  *	adding a new table. The RSDP holds pointers to the RSDT and XSDT.
  * @rsdt: Pointer to the Root System Description Table
  * @xsdt: Pointer to the Extended System Description Table
+ * @len_stack: Stack of 'length' words to fix up later
+ * @ltop: Points to current top of stack (0 = empty)
  */
 struct acpi_ctx {
 	void *current;
 	struct acpi_rsdp *rsdp;
 	struct acpi_rsdt *rsdt;
 	struct acpi_xsdt *xsdt;
+	char *len_stack[ACPIGEN_LENSTACK_SIZE];
+	int ltop;
 };
 
 /**
diff --git a/lib/acpi/acpigen.c b/lib/acpi/acpigen.c
index 1223f0d1c4..bd1fa24fb6 100644
--- a/lib/acpi/acpigen.c
+++ b/lib/acpi/acpigen.c
@@ -10,6 +10,7 @@ 
 
 #include <common.h>
 #include <dm.h>
+#include <log.h>
 #include <acpi/acpigen.h>
 #include <dm/acpi.h>
 
@@ -37,6 +38,38 @@  void acpigen_emit_dword(struct acpi_ctx *ctx, uint data)
 	acpigen_emit_byte(ctx, (data >> 24) & 0xff);
 }
 
+/*
+ * Maximum length for an ACPI object generated by this code,
+ *
+ * If you need to change this, change acpigen_write_len_f(ctx) and
+ * acpigen_pop_len(ctx)
+ */
+#define ACPIGEN_MAXLEN 0xfffff
+
+void acpigen_write_len_f(struct acpi_ctx *ctx)
+{
+	assert(ctx->ltop < (ACPIGEN_LENSTACK_SIZE - 1));
+	ctx->len_stack[ctx->ltop++] = ctx->current;
+	acpigen_emit_byte(ctx, 0);
+	acpigen_emit_byte(ctx, 0);
+	acpigen_emit_byte(ctx, 0);
+}
+
+void acpigen_pop_len(struct acpi_ctx *ctx)
+{
+	int len;
+	char *p;
+
+	assert(ctx->ltop > 0);
+	p = ctx->len_stack[--ctx->ltop];
+	len = ctx->current - (void *)p;
+	assert(len <= ACPIGEN_MAXLEN);
+	/* generate store length for 0xfffff max */
+	p[0] = (0x80 | (len & 0xf));
+	p[1] = (len >> 4 & 0xff);
+	p[2] = (len >> 12 & 0xff);
+}
+
 void acpigen_emit_stream(struct acpi_ctx *ctx, const char *data, int size)
 {
 	int i;
diff --git a/test/dm/acpigen.c b/test/dm/acpigen.c
index 3d580a23a5..f9c15b7503 100644
--- a/test/dm/acpigen.c
+++ b/test/dm/acpigen.c
@@ -22,7 +22,7 @@ 
 #define TEST_STRING	"frogmore"
 #define TEST_STREAM2	"\xfa\xde"
 
-static int alloc_context(struct acpi_ctx **ctxp)
+static int alloc_context_size(struct acpi_ctx **ctxp, int size)
 {
 	struct acpi_ctx *ctx;
 
@@ -30,7 +30,8 @@  static int alloc_context(struct acpi_ctx **ctxp)
 	ctx = malloc(sizeof(*ctx));
 	if (!ctx)
 		return -ENOMEM;
-	ctx->current = malloc(150);
+	ctx->current = malloc(size);
+	ctx->ltop = 0;
 	if (!ctx->current)
 		return -ENOMEM;
 	*ctxp = ctx;
@@ -38,6 +39,11 @@  static int alloc_context(struct acpi_ctx **ctxp)
 	return 0;
 }
 
+static int alloc_context(struct acpi_ctx **ctxp)
+{
+	return alloc_context_size(ctxp, 150);
+}
+
 static void free_context(struct acpi_ctx **ctxp)
 {
 	free(*ctxp);
@@ -334,3 +340,57 @@  static int dm_test_acpi_spi(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_acpi_spi, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/**
+ * get_length() - decode a three-byte length field
+ *
+ * @ptr: Length encoded as per ACPI
+ * @return decoded length, or -EINVAL on error
+ */
+static int get_length(u8 *ptr)
+{
+	if (!(*ptr & 0x80))
+		return -EINVAL;
+
+	return (*ptr & 0xf) | ptr[1] << 4 | ptr[2] << 12;
+}
+
+/* Test emitting a length */
+static int dm_test_acpi_len(struct unit_test_state *uts)
+{
+	const int size = 0xc0000;
+	struct acpi_ctx *ctx;
+	u8 *ptr;
+	int i;
+
+	ut_assertok(alloc_context_size(&ctx, size));
+
+	ptr = acpigen_get_current(ctx);
+
+	/* Write a byte and a 3-byte length */
+	acpigen_write_len_f(ctx);
+	acpigen_emit_byte(ctx, 0x23);
+	acpigen_pop_len(ctx);
+	ut_asserteq(1 + 3, get_length(ptr));
+
+	/* Write 200 bytes so we need two length bytes */
+	ptr = ctx->current;
+	acpigen_write_len_f(ctx);
+	for (i = 0; i < 200; i++)
+		acpigen_emit_byte(ctx, 0x23);
+	acpigen_pop_len(ctx);
+	ut_asserteq(200 + 3, get_length(ptr));
+
+	/* Write 40KB so we need three length bytes */
+	ptr = ctx->current;
+	acpigen_write_len_f(ctx);
+	for (i = 0; i < 40000; i++)
+		acpigen_emit_byte(ctx, 0x23);
+	acpigen_pop_len(ctx);
+	ut_asserteq(40000 + 3, get_length(ptr));
+
+	free_context(&ctx);
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_len, 0);